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American Wood Council
American Forest &
Paper Association
2005 EDITION
MANUAL FOR ENGINEERED WOOD CONSTRUCTION
MANUAL ASD/LRFD
Updates and Errata While every precaution has been taken to ensure the accuracy of this document, errors may have occurred during development. Updates or Errata are posted to the American Wood Council website at www.awc.org. Technical inquiries may be addressed to [email protected].
The American Wood Council (AWC) is the wood products division of the American Forest & Paper Association (AF&PA). AF&PA is the national trade association of the forest, paper, and wood products industry, representing member companies engaged in growing, harvesting, and processing wood and
and producing engineered and traditional wood products. For more information see www.afandpa.org.
2005 EDITION
Copyright © 2006 American Forest & Paper Association, Inc.
ASD/LRFD
MANUAL FOR ENGINEERED
WOOD CONSTRUCTION
AMERICAN WOOD COUNCIL
ii ASD/LRFD MANUAL FOR ENGINEERED WOOD CONSTRUCTION
ASD/LRFD Manual for Engineered Wood Construction 2005 Edition
Web Version: September 2008
ISBN 0-9625985-7-7 (Volume 3) ISBN 0-9625985-8-5 (4 Volume Set)
Copyright © 2006 by American Forest & Paper Association, Inc. All rights reserved. No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including, without limitation, electronic, optical, or mechanical means (by way of example and not limitation, photocopying, or recording by or in an information storage retrieval system) without express written permission of the American Forest & Paper Association, Inc. For information on permission to copy material, please contact: Copyright Permission AF&PA American Wood Council 1111 Nineteenth St., NW, Suite 800 Washington, DC 20036 email: [email protected]
Printed in the United States of America
AMERICAN FOREST & PAPER ASSOCIATION
iiiASD/LRFD MANUAL FOR ENGINEERED WOOD CONSTRUCTION
FOREWORD This Allowable Stress Design/Load and Resistance
Factor Design Manual for Engineered Wood Construction (ASD/LRFD Manual) provides guidance for design of most wood-based structural products used in the construction of wood buildings. The complete Wood Design Package includes this ASD/LRFD Manual and the following:
• ANSI/AF&PA NDS-2005 National Design Speci- ® (NDS®) for Wood Construction – with
Commentary; and, NDS Supplement – Design Val- ues for Wood Construction, 2005 Edition,
• ANSI/AF&PA SDPWS-05 – Special Design Pro- visions for Wind and Seismic (SDPWS) – with Commentary,
• ASD/LRFD Structural Wood Design Solved Ex- ample Problems, 2005 Edition.
The American Forest & Paper Association (AF&PA) has developed this manual for design professionals. AF&PA and its predecessor organizations have provided engineering design information to users of structural wood
Wood Structural Design Data series and then in the National
. It is intended that this document be used in conjunction
with competent engineering design, accurate fabrication, and adequate supervision of construction. AF&PA does not assume any responsibility for errors or omissions in the document, nor for engineering designs, plans, or construc- tion prepared from it.
Those using this standard assume all liability arising from its use. The design of engineered structures is within the scope of expertise of licensed engineers, architects, or other licensed professionals for applications to a particular structure.
American Forest & Paper Association
AMERICAN WOOD COUNCIL
iv ASD/LRFD MANUAL FOR ENGINEERED WOOD CONSTRUCTION
AMERICAN FOREST & PAPER ASSOCIATION
vASD/LRFD MANUAL FOR ENGINEERED WOOD CONSTRUCTION
TABLE OF CONTENTS Part/Title Page Part/Title Page
M1 GENERAL REQUIREMENTS FOR STRUCTURAL DESIGN ...........1
M1.1 Products Covered in This Manual M1.2 General Requirements M1.3 Design Procedures
M2 DESIGN VALUES FOR STRUCTURAL MEMBERS ................. 3
M2.1 General Information M2.2 Reference Design Values M2.3 Adjustment of Design Values
M3 DESIGN PROVISIONS AND EQUATIONS ....................................................... 5
M3.1 General M3.2 Bending Members - General M3.3 Bending Members - Flexure M3.4 Bending Members - Shear
n M3.6 Compression Members M3.7 Solid Columns M3.8 Tension Members M3.9 Combined Bending and Axial Loading M3.10 Design for Bearing
M4 SAWN LUMBER ..........................................11 M4.1 General M4.2 Reference Design Values M4.3 Adjustment of Reference Design
Values M4.4 Special Design Considerations M4.5 Member Selection Tables M4.6 Examples of Capacity Table
Development
M5 STRUCTURAL GLUED LAMINATED TIMBER ...........................27
M5.1 General M5.2 Reference Design Values M5.3 Adjustment of Reference Design
Values M5.4 Special Design Considerations
M6 ROUND TIMBER POLES AND PILES ...................................................... 33
M6.1 General M6.2 Reference Design Values M6.3 Adjustment of Reference Design
Values M6.4 Special Design Considerations
M7 PREFABRICATED WOOD I-JOISTS ............................................................37
M7.1 General M7.2 Reference Design Values M7.3 Adjustment of Reference Design
Values M7.4 Special Design Considerations
M8 STRUCTURAL COMPOSITE LUMBER ............................................................. 53
M8.1 General M8.2 Reference Design Values M8.3 Adjustment of Reference Design
Values M8.4 Special Design Considerations
M9 WOOD STRUCTURAL PANELS ...............................................................59
M9.1 General M9.2 Reference Design Values M9.3 Adjustment of Reference Design
Values M9.4 Special Design Considerations
M10 MECHANICAL CONNECTIONS ...........................................69
M10.1 General M10.2 Reference Design Values M10.3 Design Adjustment Factors M10.4 Typical Connection Details M10.5 Pre-Engineered Metal Connectors
M11 DOWEL-TYPE FASTENERS ........ 85 M11.1 General M11.2 Reference Withdrawal Design
Values M11.3 Reference Lateral Design Values M11.4 Combined Lateral and Withdrawal
Loads M11.5 Adjustment of Reference Design
Values M11.6 Multiple Fasteners
M12 SPLIT RING AND SHEAR PLATE CONNECTORS ........................ 89
M12.1 General M12.2 Reference Design Values M12.3 Placement of Split Ring and Shear
Plate Connectors
AMERICAN WOOD COUNCIL
vi ASD/LRFD MANUAL FOR ENGINEERED WOOD CONSTRUCTION
M13 TIMBER RIVETS ........................................91 M13.1 General M13.2 Reference Design Values M13.3 Placement of Timber Rivets
M14 SHEAR WALLS AND DIAPHRAGMS ............................................ 93
M14.1 General M14.2 Design Principles M14.3 Shear Walls M14.4 Diaphragms
M15 SPECIAL LOADING CONDITIONS .................................................99
M15.1 Lateral Distribution of Concentrated Loads
M15.2 Spaced Columns M15.3 Built-Up Columns M15.4 Wood Columns with Side Loads
and Eccentricity
Part/Title Page Part/Title Page
M16 FIRE DESIGN ............................................101 M16.1 General M16.2 Design Procedures for Exposed
Wood Members M16.3 Wood Connections
AMERICAN FOREST & PAPER ASSOCIATION
viiASD/LRFD MANUAL FOR ENGINEERED WOOD CONSTRUCTION
LIST OF TABLES
M4.3-1 Applicability of Adjustment Factors for Sawn Lumber ............................................. 13
M4.4-1 Approximate Moisture and Thermal Dimensional Changes................................. 14
ME, and Fiber Saturation Point, FSP, for Solid Woods ......................................................... 15
TE, for Solid Woods ............................................... 16
M4.5-1a ASD Tension Member Capacity (T'), Structural Lumber (2-inch nominal thickness Visually Graded Lumber (1.5 inch dry dressed size), CD = 1.0.4-inch nominal thickness Visually Graded Lumber (3.5 inch dry dressed size), CD = 1.0) ................ 18
M4.5-1b ASD Tension Member Capacity (T'), Structural Lumber (2-inch nominal thickness MSR Lumber (1.5 inch dry dressed size), CD = 1.0) .............................. 18
M4.5-2a ASD Column Capacity (P', P'x, P'y), Timbers (6-inch nominal thickness (5.5 inch dry dressed size), CD = 1.0) .............................. 19
M4.5-2b ASD Column Capacity (P', P'x, P'y), Timbers (8-inch nominal thickness (7.5 inch dry dressed size), CD = 1.0) .............................. 20
M4.5-2c ASD Column Capacity (P', P'x, P'y), Timbers (10-inch nominal thickness (9.5 inch dry dressed size), CD = 1.0) .............................. 21
M4.5-3a ASD Bending Member Capacity (M', CrM', V', and EI), Structural Lumber (2-inch nominal thickness (1.5 inch dry dressed size), CD = 1.0, CL = 1.0) ............................ 22
M4.5-3b ASD Bending Member Capacity (M', CrM', V', and EI), Structural Lumber (4-inch nominal thickness (3.5 inch dry dressed size), CD = 1.0, CL = 1.0. ............................ 22
M4.5-4a ASD Bending Member Capacity (M', V', and EI), Timbers (6-inch nominal thickness (5.5 inch dry dressed size), CD = 1.0, CL = 1.0) ..................................................... 23
M4.5-4b ASD Bending Member Capacity (M', V', and EI), Timbers (8-inch nominal thickness (7.5 inch dry dressed size), CD = 1.0, CL = 1.0)...................................... 23
M4.5-4c ASD Bending Member Capacity (M', V', and EI), Timbers (10-inch nominal thickness (9.5 inch dry dressed size), CD = 1.0, CL = 1.0)...................................... 24
M4.5-4d ASD Bending Member Capacity (M', V', and EI), Timbers (Nominal dimensions > 10 inch (actual = nominal – 1/2 inch), CD = 1.0, CL = 1.0)...................................... 24
M5.1-1 Economical Spans for Structural Glued Laminated Timber Framing Systems ......... 29
M5.3-1 Applicability of Adjustment Factors for Structural Glued Laminated Timber........... 31
Factor ......................................................... 32
M6.3-1 Applicability of Adjustment Factors for Round Timber Poles and Piles ................... 35
M7.3-1 Applicability of Adjustment Factors for Prefabricated Wood I-Joists ....................... 40
M8.3-1 Applicability of Adjustment Factors for Structural Composite Lumber .................... 56
M9.1-1 Guide to Panel Use ..................................... 61
M9.2-1 Wood Structural Panel Bending Stiffness and Strength ............................................... 62
M9.2-2 Wood Structural Panel Axial Stiffness, Tension, and Compression Capacities ........ 63
M9.2-3 Wood Structural Panel Planar (Rolling) Shear Capacities ......................................... 65
M9.2-4 Wood Structural Panel Rigidity and Through-the-Thickness Shear Capacities .. 65
M9.3-1 Applicability of Adjustment Factors for Wood Structural Panels .............................. 66
M9.4-1 Panel Edge Support .................................... 67
M9.4-2 Minimum Nailing for Wood Structural Panel Applications ...................................... 68
M10.3-1 Applicability of Adjustment Factors for Mechanical Connections ............................ 71
AMERICAN WOOD COUNCIL
viii ASD/LRFD MANUAL FOR ENGINEERED WOOD CONSTRUCTION
M11.3-1 Applicability of Adjustment Factors for Dowel-Type Fasteners ................................ 87
M12.2-1 Applicability of Adjustment Factors for Split Ring and Shear Plate Connectors ...... 90
M13.2-1 Applicability of Adjustment Factors for Timber Rivets ............................................. 92
M16.1-1 Minimum Sizes to Qualify as Heavy Timber Construction ................................ 102
M16.1-2 One-Hour Fire-Rated Load-Bearing Wood-Frame Wall Assemblies ...................103
M16.1-3 Two-Hour Fire-Rated Load-Bearing Wood-Frame Wall Assemblies .................. 103
M16.1-4 One-Hour Fire-Rated Wood Floor/Ceiling Assemblies ............................................... 104
M16.1-5 Two-Hour Fire-Rated Wood Floor/Ceiling Assemblies ............................................... 104
M16.1-6 Minimum Depths at Which Selected Beam Sizes Can Be Adopted for One-Hour Fire Ratings ..................................................... 119
M16.1-7 Fire-Resistive Wood I-Joist Floor/Ceiling Assemblies ............................................... 123
M16.1-8 Privacy Afforded According to STC Rating ....................................................... 143
M16.1-9 Contributions of Various Products to STC or IIC Rating ............................................ 143
M16.1-10 Example Calculation ................................ 144
M16.1-11 STC & IIC Ratings for UL L528/L529 .... 144
M16.1-12 STC & IIC Ratings for FC-214 ................ 144
M16.2-1 Design Load Ratios for Bending Members Exposed on Three Sides (Structural Calculations at Standard Reference Conditions: CD = 1.0, CM = 1.0, Ct = 1.0, Ci = 1.0, CL = 1.0) (Protected Surface in Depth Direction) ..................... 147
M16.2-2 Design Load Ratios for Bending Members Exposed on Four Sides (Structural Calculations at Standard Reference Conditions: CD = 1.0, CM = 1.0, Ct = 1.0, Ci = 1.0, CL=1.0) .............................................148
M16.2-3 Design Load Ratios for Compression Members Exposed on Three Sides (Structural Calculations at Standard Reference Conditions: CM = 1.0, Ct = 1.0, Ci = 1.0) (Protected Surface in Depth Direction) ................................................. 149
M16.2-4 Design Load Ratios for Compression Members Exposed on Three Sides (Structural Calculations at Standard Reference Conditions: CM = 1.0, Ct = 1.0, Ci = 1.0) (Protected Surface in Width Direction) ................................................. 150
M16.2-5 Design Load Ratios for Compression Members Exposed on Four Sides (Structural Calculations at Standard Reference Conditions: CM = 1.0, Ct = 1.0, Ci = 1.0) .................................................... 151
M16.2-6 Design Load Ratios for Tension Members Exposed on Three Sides (Structural Calculations at Standard Reference Conditions: CD = 1.0, CM = 1.0, Ct = 1.0, Ci = 1.0) (Protected Surface in Depth Direction) ................................................. 152
M16.2-7 Design Load Ratios for Tension Members Exposed on Three Sides (Structural Calculations at Standard Reference Conditions: CD = 1.0, CM = 1.0, Ct = 1.0, Ci = 1.0) (Protected Surface in Width Direction) ................................................. 153
M16.2-8 Design Load Ratios for Tension Members Exposed on Four Sides (Structural Calculations at Standard Reference Conditions: CD = 1.0, CM = 1.0, Ct = 1.0, Ci = 1.0) .................................................... 154
M16.2-9 Design Load Ratios for Exposed Timber Decks (Double and Single Tongue & Groove Decking) (Structural Calculations at Standard Reference Conditions: CD = 1.0, CM = 1.0, Ct = 1.0, Ci = 1.0) ...... 155
M16.2-10 Design Load Ratios for Exposed Timber Decks (Butt-Joint Timber Decking) (Structural Calculations at Standard Reference Conditions: CD = 1.0, CM = 1.0, Ct = 1.0, Ci = 1.0) ..................................... 155
AMERICAN FOREST & PAPER ASSOCIATION
ixASD/LRFD MANUAL FOR ENGINEERED WOOD CONSTRUCTION
LIST OF FIGURES
M5.1-1 Unbalanced and Balanced Layup Combinations ............................................. 28
M5.2-1 Loading in the X-X and Y-Y Axes ............. 30
M7.4-1 Design Span Determination ....................... 41
M7.4-2 Load Case Evaluations ............................... 43
M7.4-3 End Bearing Web Stiffeners (Bearing Block) ......................................................... 45
M7.4-4 Web Stiffener Bearing Interface ................. 46
M7.4-5 Beveled End Cut ........................................ 46
M7.4-6 Sloped Bearing Conditions (Low End) ...... 47
M7.4-7 Sloped Bearing Conditions (High End) ..... 48
M7.4-8 Lateral Support Requirements for Joists in Hangers ................................................. 49
M7.4-9 Top Flange Hanger Support ....................... 49
M7.4-10 Connection Requirements for Face Nail Hangers ...................................................... 50
M7.4-11 Details for Vertical Load Transfer .............. 51
M9.2-1 Structural Panel with Strength Direction Across Supports ......................................... 60
M9.2-2 Example of Structural Panel in Bending .... 60
M9.2-3 Structural Panel with Axial Compression Load in the Plane of the Panel.................... 64
M9.2-4 Through-the-Thickness Shear for Wood Structural Panels ................................................. 64
M9.2-5 Planar (Rolling) Shear or Shear-in-the- Plane for Wood Structural Panels ............... 64
M14.2-1 Shear Wall Drag Strut ................................ 94
M14.2-2 Shear Wall Special Case Drag Strut ........... 95
M14.2-3 Diaphragm Drag Strut (Drag strut parallel to loads) ...................................................... 95
M14.2-4 Diaphragm Chord Forces ........................... 96
M14.3-1 Overturning Forces (no dead load) ............ 97
M14.3-2 Overturning Forces (with dead load) ......... 97
M16.1-1 One-Hour Fire-Resistive Wood Wall Assembly (WS4-1.1) (2x4 Wood Stud Wall - 100% Design Load - ASTM E119/NFPA 251) ...................................... 105
M16.1-2 One-Hour Fire-Resistive Wood Wall Assembly (WS6-1.1) (2x6 Wood Stud Wall - 100% Design Load - ASTM E119/NFPA 251) ...................................... 106
M16.1-3 One-Hour Fire-Resistive Wood Wall Assembly (WS6-1.2) (2x6 Wood Stud Wall - 100% Design Load - ASTM E119/NFPA 251) ...................................... 107
M16.1-4 One-Hour Fire-Resistive Wood Wall Assembly (WS6-1.4) (2x6 Wood Stud Wall - 100% Design Load - ASTM E119/NFPA 251) ...................................... 108
M16.1-5 One-Hour Fire-Resistive Wood Wall Assembly (WS4-1.2) (2x4 Wood Stud Wall - 100% Design Load - ASTM E119/NFPA 251 ........................................ 109
M16.1-6 One-Hour Fire-Resistive Wood Wall Assembly (WS4-1.3) (2x4 Wood Stud Wall - 78% Design Load - ASTM E119/NFPA 251) ...................................... 110
M16.1-7 One-Hour Fire-Resistive Wood Wall Assembly (WS6-1.3) (2x6 Wood Stud Wall - 100% Design Load - ASTM E119/NFPA 251) .......................................111
M16.1-8 One-Hour Fire-Resistive Wood Wall Assembly (WS6-1.5) (2x6 Wood Stud Wall - 100% Design Load - ASTM E119/NFPA 25) ........................................ 112
M16.1-9 Two-Hour Fire-Resistive Wood Wall Assembly (WS6-2.1) (2x6 Wood Stud Wall - 100% Design Load - ASTM E119/NFPA 251) ...................................... 113
M16.1-10 One-Hour Fire-Resistive Wood Floor/Ceiling Assembly (2x10 Wood Joists 16" o.c. – Gypsum Directly Applied or on Optional Resilient Channels) ................... 114
AMERICAN WOOD COUNCIL
x ASD/LRFD MANUAL FOR ENGINEERED WOOD CONSTRUCTION
M16.1-11 One-Hour Fire-Resistive Wood Floor/Ceiling Assembly (2x10 Wood Joists 16" o.c. – Suspended Acoustical Ceiling Panels) ...................................................... 115
M16.1-12 One-Hour Fire-Resistive Wood Floor/Ceiling Assembly (2x10 Wood Joists 16" o.c. – Gypsum on Resilient Channels) ............ 116
M16.1-13 One-Hour Fire-Resistive Wood Floor/Ceiling Assembly (2x10 Wood Joists 24" o.c. – Gypsum on Resilient Channels) ................................................. 117
M16.1-14 Two-Hour Fire-Resistive Wood Floor/Ceiling Assembly (2x10 Wood Joists 16" o.c. – Gypsum Directly Applied with Second Layer on Resilient Channels) ................................................. 118
M16.1-15 One-Hour Fire-Resistive Ceiling Assembly (WIJ-1.1) (Floor/Ceiling - 100% Design Load - 1-Hour Rating - ASTM E119/NFPA 251) ...................................... 124
M16.1-16 One-Hour Fire-Resistive Ceiling Assembly (WIJ-1.2) (Floor/Ceiling - 100% Design Load - 1 Hour Rating - ASTM E119/NFPA 251) .......................... 125
M16.1-17 One-Hour Fire-Resistive Ceiling Assembly (WIJ-1.3) (Floor/Ceiling - 100% Design Load - 1-Hour Rating - ASTM E119/NFPA 251) .......................... 126
M16.1-18 One-Hour Fire-Resistive Ceiling Assembly (WIJ-1.4) (Floor/Ceiling - 100% Design Load - 1-Hour Rating - ASTM E119/NFPA 251) .......................... 127
M16.1-19 One-Hour Fire-Resistive Ceiling Assembly (WIJ-1.5) (Floor/Ceiling - 100% Design Load - 1-Hour Rating - ASTM E119/NFPA 251) .......................... 128
M16.1-20 One-Hour Fire-Resistive Ceiling Assembly (WIJ-1.6) (Floor/Ceiling - 100% Design Load - 1-Hour Rating - ASTM E119/NFPA 251) .......................... 129
M16.1-21 Two-Hour Fire-Resistive Ceiling Assembly (WIJ-2.1) (Floor/Ceiling - 100% Design Load - 2-Hour Rating - ASTM E119/NFPA 251) .......................... 130
M16.1-22 Cross Sections of Possible One-Hour Area Separations ...................................... 139
M16.1-23 Examples of Through-Penetration Firestop Systems ...................................... 142
M16.3-1 Beam to Column Connection - Connection Not Exposed to Fire .............. 159
M16.3-2 Beam to Column Connection - Connection Exposed to Fire Where Appearance is a Factor ....................................................... 159
M16.3-3 Ceiling Construction ............................... 159
M16.3-4 Beam to Column Connection - Connection Exposed to Fire Where Appearance is Not a Factor .............................................. 159
M16.3-5 Column Connections Covered ................ 160
M16.3-6 Beam to Girder - Concealed Connection ............................................... 160
1
1
ASD/LRFD MANUAL FOR ENGINEERED WOOD CONSTRUCTION
AMERICAN FOREST & PAPER ASSOCIATION
M1: GENERAL REQUIREMENTS FOR STRUCTURAL DESIGN
M1.1 Products Covered in This Manual 2
M1.2 General Requirements 2
M1.2.1 Bracing 2
M1.3 Design Procedures 2
AMERICAN WOOD COUNCIL
2 M1: GENERAL REQUIREMENTS FOR STRUCTURAL DESIGN
M1.1 Products Covered in This Manual This Manual was developed with the intention of cov-
ering all structural applications of wood-based products and their connections that meet the requirements of the referenced standards. The Manual is a dual format docu- ment incorporating design provisions for both allowable stress design (ASD) and load and resistance factor design (LRFD). Design information is available for the following list of products. Each product chapter contains information for use with this Manual and the National Design Speci-
. Chapters are organized to parallel the chapter format of the NDS.
• Sawn Lumber Chapter 4 • Structural Glued Laminated Timber Chapter 5 • Round Timber Poles and Piles Chapter 6 • Prefabricated Wood I-Joists Chapter 7
M1.2 General Requirements
• Structural Composite Lumber Chapter 8 • Wood Structural Panels Chapter 9 • Mechanical Connections Chapter 10 • Dowel-Type Fasteners Chapter 11 • Split Ring and Shear Plate Connectors Chapter 12 • Timber Rivets Chapter 13 • Shear Walls and Diaphragms Chapter 14
An additional Supplement, entitled Special Design Provisions for Wind and Seismic (SDPWS), has been developed to cover materials, design, and construction of wood members, fasteners, and assemblies to resist wind and seismic forces.
This Manual is organized as a multi-part package for
this package are:
• NDS and Commentary; and, NDS Supplement: Design Values for Wood Construction,
• Special Design Provisions for Wind and Seismic (SDPWS) and Commentary,
• Structural Wood Design Solved Example Prob- lems.
M1.2.1 Bracing
Design considerations related to both temporary and
discussion of bracing is included in the product chapter.
M1.3 Design Procedures The NDS
design provisions for ASD and LRFD. Behavioral equa- tions, such as those for member and connection design, are the same for both ASD and LRFD. Adjustment factor tables include applicable factors for determining an adjusted ASD design value or an adjusted LRFD design value. NDS Appendix N – (Mandatory) Load and Resistance Factor Design (LRFD) outlines requirements that are unique to LRFD and adjustment factors for LRFD.
The basic design equations for ASD or LRFD require
exceed the actual (applied) stress or other effect imposed
are set very low, and the nominal load magnitudes are set
at once-in-a-lifetime service load levels. This combina- tion produces designs that maintain high safety levels yet remain economically feasible.
From a user’s standpoint, the design process is simi- lar using LRFD. The most obvious difference between LRFD and ASD is that both the adjusted design values and load effect values in ASD will be numerically much lower than in LRFD. The adjusted design values are lower
adjustments. The load effects are lower because they are nominal (service) load magnitudes. The load combination equations for use with ASD and LRFD are given in the model building codes.
3ASD/LRFD MANUAL FOR ENGINEERED WOOD CONSTRUCTION
AMERICAN FOREST & PAPER ASSOCIATION
M2: DESIGN VALUES FOR STRUCTURAL MEMBERS
M2.1 General Information 4
M2.2 Reference Design Values 4
M2.3 Adjustment of Design Values 4
2
AMERICAN WOOD COUNCIL
4 M2: DESIGN VALUES FOR STRUCTURAL MEMBERS
M2.1 General Information
M2.3 Adjustment of Design Values
Structural wood products are provided to serve a wide range of end uses. Some products are marketed through
standards and the selection of the appropriate product is the responsibility of the user.
Other products are custom manufactured to meet the
are metal plate connected wood trusses and custom struc- tural glued laminated timbers. Design of the individual
engineer of record on the project. Manufacture of these products is performed in accordance with the product’s manufacturing standards. Engineering of these products normally only extends to the design of the products themselves. Construction-related issues, such as load path analysis and erection bracing, remain the responsibility of the professional of record for the project.
M2.2 Reference Design Values Reference design value designates the allowable
stress design value based on normal load duration. To avoid confusion, the descriptor “reference” is used and serves as a reminder that design value adjustment factors are applicable for design values in accordance with refer-
NDS – such as normal load duration.
Reference design values for sawn lumber and struc- tural glued laminated timber are contained in the NDS
Supplement: Design Values for Wood Construction. Ref- erence design values for round timber poles and piles, dowel-type fasteners, split ring and shear plate connectors, and timber rivets are contained in the NDS. Reference de- sign values for all other products are typically contained in the manufacturer’s code evaluation report.
Adjusted design value designates reference design values which have been multiplied by adjustment factors. Basic requirements for design use terminology applicable to both ASD and LRFD. In equation format, this takes the standard form fb b LRFD. Reference design values (Fb, Ft, Fv, Fc, Fc , E, Emin) are multiplied by adjustment factors to determine adjusted design values (Fb t v c c min
majority of wood products used in interior or in protected environments will require no adjustment for moisture, temperature, or treatment effects.
Moisture content (MC) reference conditions are 19% or less for sawn lumber products. The equivalent limit for glued products (structural glued laminated timber, struc- tural composite lumber, prefabricated wood I-joists, and
Temperature reference conditions include sustained temperatures up to 100ºF. Note that it has been tradition- ally assumed that these reference conditions also include common building applications in desert locations where daytime temperatures will often exceed 100ºF. Examples of applications that may exceed the reference temperature
range include food processing or other industrial build- ings.
Tabulated design values and capacities are for un- treated members. Tabulated design values and capacities also apply to wood products pressure treated by an ap-
load duration factors. An unincised reference condition is assumed. For
members that are incised to increase penetration of pre- servative chemicals, use the incising adjustment factors given in the product chapter.
strength shall be accounted for in the design. Reference design values, including connection design values, for lumber and structural glued laminated timber pressure-
from the company providing the treatment and redrying service. The impact load duration factor shall not apply
chemicals.
5ASD/LRFD MANUAL FOR ENGINEERED WOOD CONSTRUCTION
AMERICAN FOREST & PAPER ASSOCIATION
M3: DESIGN PROVISIONS AND EQUATIONS
M3.1 General 6
M3.2 Bending Members - General 6
M3.3 Bending Members - Flexure 6
M3.4 Bending Members - Shear 6
7
M3.6 Compression Members 7
M3.7 Solid Columns 8
M3.8 Tension Members 8
M3.8.1 Tension Parallel to Grain 8
M3.8.2 Tension Perpendicular to Grain 8
M3.9 Combined Bending and Axial Loading 9
M3.10 Design for Bearing 10
3
AMERICAN WOOD COUNCIL
6 M3: DESIGN PROVISIONS AND EQUATIONS
M3.1 General This Chapter covers design of members for bending,
compression, tension, combined bending and axial loads, and bearing.
M3.2 Bending Members - General This section covers design of members stressed pri-
include primary framing members (beams) and secondary framing members (purlins, joists). Products commonly used in these applications include glulam, solid sawn lumber, structural composite lumber, and prefabricated I-joists.
Bending members are designed so that no design ca- pacity is exceeded under applied loads. Strength criteria for bending members include bending moment, shear, local buckling, lateral torsional buckling, and bearing.
capacities (joist and beam selection tables) and reference bending and shear design values.
M3.3 Bending Members - Flexure The basic equation for moment design of bending
members is:
M M (M3.3-1)
where: M = adjusted moment capacity
M = bending moment
M3.4 Bending Members - Shear
The equation for calculation of adjusted moment capacity is:
M = F b S (M3.3-2)
where: S = section modulus, in.3
Fb = adjusted bending design value, psi. See product chapters for applicable adjustment factors.
The basic equation for shear design of bending mem- bers is:
V V (M3.4-1)
where: V = adjusted shear capacity parallel to
grain, lbs
V = shear force, lbs
The equation for calculation of shear capacity is:
V = Fv Ib/Q (M3.4-2)
which, for rectangular unnotched bending members, reduces to:
V = 2/3 (Fv ) A (M3.4-3)
where:
I = moment of inertia, in.4
A = area, in.2
Fv = adjusted shear design value, psi. See product chapters for applicable adjustment factors.
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M3.6 Compression Members
M3.5 Bending Members - Deflection Users should note that design of bending members is
often controlled by serviceability limitations rather than
and vibration, are often designated by the authority having jurisdiction.
For a simple span uniformly loaded rectangular member,
5 384
4w EI
(M3.5-1)
where: = deflection, in.
w = uniform load, lb/in.
= span, in.
E I = stiffness of beam section, lb-in.2
Values of modulus of elasticity, E, and moment of inertia, I, for lumber and structural glued laminated timber for use in the preceding equation can be found in the NDS Supplement. Engineered wood products such as I-joists and structural composite lumber will have EI values published in individual manufacturer’s product literature or evalua- tion reports. Some manufacturers might publish “true” E which would require additional computations to account
NDS Appendix F for information
This section covers design of members stressed pri- marily in compression parallel to grain. Examples of such members include columns, truss members, and diaphragm chords.
Information in this section is limited to the case in which loads are applied concentrically to the member. Provisions of NDS 3.9 or NDS Chapter 15 should be used if loads are eccentric or if the compressive forces are ap- plied in addition to bending forces.
The NDS differentiates between solid, built-up, and spaced columns. In this context built-up columns are assembled from multiple pieces of similar members con- nected in accordance with NDS 15.3.
A spaced column must comply with provisions of NDS -
ments, spacer blocks with their connectors and end blocks with shear plate or split ring connectors.
Compression Parallel to Grain
The basic equation for design of compression mem- bers is:
P P (M3.6-1)
where: P = adjusted compression parallel to
grain capacity, lbs
P = compressive force, lbs
The complete equation for calculation of adjusted compression capacity is:
P = Fc A (M3.6-2)
where: A = area, in.2
Fc = adjusted compression parallel to grain design value, psi. See product chapters for applicable adjustment factors.
Special Considerations
Net Section Calculation As in design of tension members, compression mem-
bers should be checked both on a gross section and a net section basis (see NDS 3.6.3).
Bearing Capacity Checks Design for bearing is addressed in NDS 3.10.
Radial Compression in Curved Members Stresses induced in curved members under load in-
clude a component of stress in the direction of the radius of curvature. Radial compression is a specialized design consideration that is addressed in NDS 5.4.1.
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M3.7 Solid Columns
M3.8 Tension Members This section covers design of members stressed
primarily in tension parallel to grain. Examples of such members include shear wall end posts, truss members, and diaphragm chords.
The designer is advised that use of wood members in applications that induce tension perpendicular to grain stresses should be avoided.
M3.8.1 Tension Parallel to Grain
The basic equation for design of tension members is:
T T (M3.8-1)
where: T = adjusted tension parallel to grain
capacity, lbs
T = tensile force, lbs
The equation for calculation of adjusted tension ca- pacity is:
T = Ft A (M3.8-2)
where: A = area, in.2
Ft = adjusted tension design value, psi. See product chapters for applicable adjustment factors.
Net Section Calculation Design of tension members is often controlled by the
ability to provide connections to develop tensile forces within the member. In the area of connections, one must design not only the connection itself (described in detail in Chapter M10) but also the transfer of force across the net section of the member. One method for determining these stresses is provided in NDS Appendix E.
M3.8.2 Tension Perpendicular to Grain
Radial Stress in Curved Members Stresses induced in curved members under load in-
clude a component of stress in the direction of the radius of curvature. This stress is traditionally called radial ten- sion. Radial stress design is a specialized consideration that is covered in NDS 5.4.1 and is explained in detail in the American Institute of Timber Construction (AITC) Timber Construction Manual.
Slenderness Considerations and Stability
The user is cautioned that stability calculations are highly dependent upon boundary conditions assumed in the analysis. For example, the common assumption of a pinned-pinned column is only accurate or conservative if the member is restrained against sidesway. If sidesway is possible and a pinned-free condition exists, the value of Ke in NDS 3.7.1.2 doubles (see NDS Appendix Table G1
e) and the computed adjusted compression parallel to grain capacity decreases.
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M3.9 Combined Bending and Axial Loading
Members must be designed by multiplying all ap- plicable adjustment factors by the reference design values for the product. See M3.3 and M3.6 for discussion of ap- plicable adjustment factors for bending or compression, respectively.
Design Techniques
A key to understanding design of members under combined bending and axial loads is that components of the design equation are simple ratios of compressive force (or moment) to compression capacity (or moment capacity). Note that the compression term in this equa- tion is squared. This is the result of empirical test data. Moderate compressive forces do not have as large an impact on capacity (under combined loads) as previously thought. It is believed that this is the result of compressive “reinforcing” of what would otherwise be a tensile failure mode in bending.
This section covers design of members stressed under combined bending and axial loads. The applicable strength criteria for these members is explicit in the NDS equations – limiting the sum of various stress ratios to less than or equal to unity.
Bending and Axial Tension
For designs in which the axial load is in tension rather than compression, the designer should use NDS Equations 3.9-1 and 3.9-2.
Bending and Axial Compression
The equation for design of members under bending plus compression loads is given below in terms of load and moment ratios:
P P
M
M P
P
M
M P
P M ME E E
2 1
1 1
2
2 2
1
2
1 1
1 0. (M3.9-1)
where P = adjusted compression capacity
determined per M3.6, lbs
P = compressive force determined per M3.6, lbs
M1 = adjusted moment capacity (strong axis) determined per M3.3, in.-lbs
M1 = bending moment (strong axis) determined per M3.3, in.-lbs
M2 = adjusted moment capacity (weak axis) determined per M3.3, in.-lbs
M2 = bending moment (weak axis) determined per M3.3, in.-lbs
PE1 = FcE1 A = critical column buckling capacity (strong axis) determined per NDS 3.9.2, lbs
PE2 = FcE2 A = critical column buckling capacity (weak axis) determined per NDS 3.9.2, lbs
ME = FbE S = critical beam buckling capacity determined per NDS 3.9.2, in.-lbs
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M3.10 Design for Bearing Columns often transfer large forces within a structural
system. While satisfaction of column strength criteria is usually the primary concern, the designer should also check force transfer at the column bearing.
For cases in which the column is bearing on another wood member, especially if bearing is perpendicular to grain, this calculation will often control the design.
The basic equation for bearing design is:
R R (M3.10-1)
where: R = adjusted compression perpendicular
to grain capacity, lbs
R = compressive force or reaction, lbs
The equation for calculation of adjusted compression perpendicular to grain capacity is:
R = Fc A (M3.10-2)
where: A = area, in.2
Fc = adjusted compression perpendicular to grain design value, psi. See product chapters for applicable adjustment factors.
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M4.1 General 12
M4.2 Reference Design Values 12
M4.3 Adjustment of Reference Design Values 13
M4.4 Special Design Considerations 14
M4.5 Member Selection Tables 17
M4.6 Examples of Capacity Table Development 25
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M4.1 General Product Information
Structural lumber products are well-known through- out the construction industry. The economic advantages of lumber often dictate its choice as a preferred building material.
Lumber is available in a wide range of species, grades, sizes, and moisture contents. Structural lumber products
or by the species, grade, and size required. This Chapter provides information for designing struc-
tural lumber products in accordance with the NDS.
Common Uses
Structural lumber and timbers have been a primary construction material throughout the world for many cen- turies. They are the most widely used framing material for housing in North America.
broad use in commercial and industrial construction. Its high strength, universal availability, and cost saving at- tributes make it a viable option in most low- and mid-rise construction projects.
Structural lumber is used as beams, columns, headers, joists, rafters, studs, and plates in conventional construc- tion. In addition to its use in lumber form, structural lumber is used to manufacture structural glued laminated beams, trusses, and wood I-joists.
Availability
Structural lumber is a widely available construction
aware of the species, grades, and sizes available locally. The best source of this information is your local lumber supplier.
M4.2 Reference Design Values
General
The NDS Supplement provides reference design values for design of sawn lumber members. These design values are used when manual calculation of member capacity is required and must be used in conjunction with the adjust-
NDS 4.3.
Reference Design Values
Reference design values are provided in the NDS Supplement as follows:
NDS Supplement Table Number 4A and 4B Visually graded dimension lumber 4C Mechanically graded dimension lumber 4D Visually graded timbers 4E Visually graded decking 4F Non-North American visually graded
dimension lumber
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M4.3 Adjustment of Reference Design Values To generate member design capacities, reference de-
sign values for sawn lumber are multiplied by adjustment factors and section properties per Chapter M3. Applicable
NDS 4.3. Table M4.3-1 shows the applicability of adjustment factors for sawn lumber in a slightly different format for the designer.
Allowable Stress Design Load and Resistance Factor Design Fb b CD CM Ct CL CF Cfu Ci Cr Fb b CM Ct CL CF Cfu Ci Cr KF b Ft t CD CM Ct CF Ci Ft t CM Ct CF Ci KF t Fv v CD CM Ct Ci Fv v CM Ct Ci KF v Fc c CM Ct Ci Cb Fc c CM Ct Ci Cb KF c Fc c CD CM Ct CF Ci CP Fc c CM Ct CF Ci CP KF c
M Ct Ci M Ct Ci Emin min CM Ct Ci CT Emin min CM Ct Ci CT KF s
Bending Member Example For unincised, straight, laterally supported bending
members stressed in edgewise bending in single member use and used in a normal building environment (meeting the reference conditions of NDS 2.3 and 4.3), the adjusted design values reduce to:
For ASD: Fb = Fb CD CF
Fv = Fv CD
Fc = Fc Cb
E = E
Emin = Emin
For LRFD: Fb = Fb CF KF b
Fv = Fv KF v
Fc = Fc Cb KF c
E = E
Emin = Emin KF s
Axially Loaded Member Example For unincised axially loaded members used in a normal
building environment (meeting the reference conditions of NDS 2.3 and 4.3) designed to resist tension or compression loads, the adjusted tension or compression design values reduce to:
For ASD: Fc = Fc CD CF CP
Ft = Ft CD CF
Emin = Emin
For LRFD: Fc = Fc CF CP KF c
Ft = Ft CF KF t
Emin = Emin KF s
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Table M4.4-1 Approximate Moisture and Thermal Dimensional Changes
Equations for Computing Moisture and Thermal Shrinkage/Expansion
Due to Moisture Changes For more precise computation of dimensional changes
due to changes in moisture, the change in radial (R), tan- gential (T), and volumetric (V) dimensions due to changes in moisture content can be calculated as:
X X MC eo ME (M4.4-1)
where: X0 = initial dimension or volume
X = new dimension or volume
MC = moisture content change (%)
eME = coefficient of moisture expansion: linear (in./in./%MC) or volumetric (in.3/in.3/%MC)
and:
MC M Mo (M4.4-2)
where: Mo = initial moisture content % (Mo FSP)
M = new moisture content % (M FSP)
FSP = fiber saturation point
Values for eME and FSP are shown in Table M4.4-2.
Description Radial or Tangential Direction Dimensional change due to moisture content change1 1% change in dimension per 4% change in MC Dimensional change due to temperature change2 20 × 10-6 in./in. per degree F 1. Corresponding longitudinal direction shrinkage/expansion is about 1% to 5% of that in radial and tangential directions.
M4.4 Special Design Considerations General
With proper detailing and protection, structural lumber can perform well in a variety of environments. One key to proper detailing is planning for the natural shrinkage and swelling of wood members as they are subjected to various drying and wetting cycles. While moisture changes have the largest impact on lumber dimensions, some designs must also check the effects of temperature on dimensions as well.
Dimensional Changes
conservative (yielding more shrinkage and expansion than one might expect for most species). This level of information should be adequate for common structural ap- plications. Equations are provided in this section for those designers who require more precise calculations.
resistance is discussed in Chapter M16.
Due to Temperature Changes For more precise calculation of dimensional changes
due to changes in temperature, the shrinkage/expansion of solid wood including lumber and timbers can be cal- culated as:
X X T eo TE (M4.4-3)
where: X0 = reference dimension at T0
X = computed dimension at T
T0 = reference temperature (°F)
T = temperature at which the new dimension is calculated (°F)
eTE = coefficient of thermal expansion (in./in./°F)
and:
T T To (M4.4-4)
where:
To
parallel to grain ranges from about 1.7 × 10-6 to 2.5 × 10-6
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Table M4.4-2 Coefficient of Moisture Expansion, eME, and Fiber Saturation Point, FSP, for Solid Woods
eME
Species Radial
(in./in./%) Tangential (in./in./%)
Volumetric (in.3/in.3/%)
FSP (%)
Alaska Cedar 0.0010 0.0021 0.0033 28 Douglas Fir-Larch 0.0018 0.0033 0.0050 28 Englemann Spruce 0.0013 0.0024 0.0037 30 Redwood 0.0012 0.0022 0.0032 22 Red Oak 0.0017 0.0038 0.0063 30 Southern Pine 0.0020 0.0030 0.0047 26 Western Hemlock 0.0015 0.0028 0.0044 28 Yellow Poplar 0.0015 0.0026 0.0041 31
(radial and tangential) are proportional to wood density.
Radial:
e G FTE 18 5 5 10 6. /in./in. (M4.4-5)
Tangential:
e G FTE 18 10 2 10 6. /in./in. (M4.4-6)
where:
Table M4.4-3 provides the numerical values for eTE for the most commonly used commercial species or spe- cies groups.
Wood that contains moisture reacts to varying tem- perature differently than does dry wood. When moist wood is heated, it tends to expand because of normal thermal expansion and to shrink because of loss in moisture con- tent. Unless the wood is very dry initially (perhaps 3% or 4% MC or less), the shrinkage due to moisture loss on heating will be greater than the thermal expansion, so the net dimensional change on heating will be negative. Wood at intermediate moisture levels (about 8% to 20%)
volume smaller than the initial volume, as the wood gradu- ally loses water while in the heated condition.
Even in the longitudinal (grain) direction, where di- mensional change due to moisture change is very small, such changes will still predominate over corresponding dimensional changes due to thermal expansion unless
the wood is very dry initially. For wood at usual moisture levels, net dimensional changes will generally be negative after prolonged heating.
Calculation of actual changes in dimensions can be accomplished by determining the equilibrium moisture content of wood at the temperature value and relative hu- midity of interest. Then the relative dimensional changes due to temperature change alone and moisture content change alone are calculated. By combining these two
established.
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Durability
Designing for durability is a key part of the architec- tural and engineering design of the building. This issue is particularly important in the design of buildings that use poles and piles. Many design conditions can be detailed to minimize the potential for decay; for other problem conditions, preservative-treated wood or naturally durable
This section does not cover the topic of designing for durability in detail. There are many excellent texts on the topic, including AF&PA’s Design of Wood Structures for Permanence, WCD No. 6. Designers are advised to use this
design areas, such as:
structures in moist or humid conditions where wood comes in contact with concrete
or masonry where wood members are supported in steel
hangers or connectors in which condensation could collect
anywhere that wood is directly or indirectly exposed to the elements
where wood, if it should ever become wet, could not naturally dry out.
This list is not intended to be all-inclusive – it is merely an attempt to alert designers to special conditions that may cause problems when durability is not considered in the design.
Table M4.4-3 Coefficient of Thermal Expansion, eTE, for Solid Woods
eTE Species Radial (10-6 in./in./°F) Tangential (10-6 in./in./°F) California Redwood 13 18 Douglas Fir-Larch1 15 19 Douglas Fir, South 14 19 Eastern Spruce 13 18 Hem-Fir1 13 18 Red Oak 18 22 Southern Pine 15 20 Spruce-Pine-Fir 13 18 Yellow Poplar 14 18 1. Also applies when species name includes the designation “North.”
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ASD Capacity Tables
ASD capacity tables are provided as follows:
Table M4.5-1 = tension members Table M4.5-2 = compression members (timbers) Table M4.5-3 = bending members (lumber) Table M4.5-4 = bending members (timber)
Refer to the selection table checklist to see whether your design condition meets the assumptions built into the tabulated values. Note that the load duration factor, CD, is shown at the top of the table. Thus, the member design capacity can be used directly to select a member that meets the design requirement.
Examples of the development of the capacity table values are shown in M4.6.
Compression member tables are based on concentric axial loads only and pin-pin end conditions. Bending member tables are based on uniformly distributed loads on a simple span beam. Values from the compression or tension member tables and bending member tables can- not be combined in an interaction equation to determine combined bending and axial loads. See NDS 3.9 for more information.
M4.5 Member Selection Tables
General
Member selection tables provide ASD capacities for many common designs. Before using the selection tables, refer to the footnotes to be certain that the tables are ap- propriate for the application.
The tables in this section provide design capacity values for structural lumber and timbers. Moment capac- ity, M , shear capacity, V , and bending stiffness, EI, are provided for strong-axis bending. Tension capacity, T , and compression capacity, P , are also tabulated. The ap- plicable load duration factor, CD, is indicated in each of the tables.
Footnotes are provided to allow conversion to load and resistance factor design (LRFD) capacities. See NDS Appendix N for more details on LRFD.
For manual calculation, two approaches are possible: 1) review the design equations in the chapter and modify the tabulated values as necessary; or 2) compute design capacity directly from the reference design values and adjustment factors.
- tion, apply the design equations directly. Reference design values are provided in Chapter 4 of the NDS Supplement and design adjustment factors are provided in NDS 4.3.
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Table M4.5-1a ASD Tension Member Capacity (T'), Structural Lumber1,2 2-inch nominal thickness Visually Graded Lumber (1.5 inch dry dressed size), CD = 1.0.
4-inch nominal thickness Visually Graded Lumber (3.5 inch dry dressed size), CD = 1.0.
Table M4.5-1b ASD Tension Member Capacity (T'), Structural Lumber1,2 2-inch nominal thickness MSR Lumber (1.5 inch dry dressed size), CD = 1.0.
NDS Appendix N for more information. 2. Tabulated values apply to members in a dry service condition, CM = 1.0; normal temperature range, Ct = 1.0; and unincised members, Ci = 1.0.
Tension Member Capacity, T' (lbs)
Visually Graded Lumber
Width 2" nominal thickness 4" nominal thickness
Nominal Actual Select Select
Species in. in. Structural No. 1 No. 2 No. 3 Structural No. 1 No. 2
4 3.5 7,870 5,310 4,520 2,550 18,300 12,400 10,500
6 5.5 10,700 7,230 6,160 3,480 25,000 16,800 14,300
Douglas Fir-Larch 8 7.25 13,000 8,000 7,500 4,240 30,400 20,500 17,500
10 9.25 15,260 10,300 8,770 4,960 35,600 24,000 20,400
12 11.25 16,800 11,900 9,700 5,480 39,300 26,500 22,600
4 3.5 7,280 4,920 4,130 2,360 16,900 11,400 9,640
6 5.5 9,900 6,700 5,630 3,210 23,100 15,600 13,100
Hem-Fir 8 7.25 12,000 8,150 6,850 3,910 28,100 19,000 15,900
10 9.25 14,100 9,530 8,010 4,570 32,900 22,200 18,600
12 11.25 15,600 10,500 8,850 5,060 36,400 24,600 20,600
4 3.5 8,400 5,510 4,330 2,490 19,600 12,800 10,100
6 5.5 11,500 7,420 5,980 3,500 26,900 17,300 13,900
Southern Pine 8 7.25 14,100 8,970 7,060 4,350 32,900 20,900 16,400
10 9.25 15,200 10,000 9,280 4,500 35,600 23,400 18,600
12 11.25 17,700 11,300 9,280 5,480 41,300 26,500 21,600
4 3.5 5,510 3,540 3,540 1,960 12,800 8,260 8,260
6 5.5 7,510 4,820 4,280 2,680 17,500 11,200 11,200
Spruce-Pine-Fir 8 7.25 9,130 5,870 5,870 3,260 21,300 13,700 13,700
10 9.25 10,600 6,860 6,860 3,810 24,900 16,000 16,000
12 11.25 11,800 7,590 7,590 4,210 27,500 17,700 17,700
2" nominal thickness 4" nominal thickness
Construction Standard Utility Stud Construction Standard Stud
Douglas Fir-Larch 4 3.5 3,410 1,960 919 2,590 7,960 4,590 6,060
Hem-Fir 4 3.5 3,150 1,700 788 2,310 7,350 3,980 5,390
Southern Pine 4 3.5 3,280 1,830 919 2,490 7,560 4,280 5,810
Spruce-Pine-Fir 4 3.5 2,620 1,440 656 2,020 6,120 3,360 4,710
Tension Member Capacity, T' (lbs)
Width Machine Stress Rated Lumber
Nominal Actual 2" nominal thickness
Species in. in. 1200f-1.2E 1350f-1.3E 1450f-1.3E 1650f-1.5E 2100f-1.8E 2250f-1.9E 2400f-2.0E
4 3.5 3,150 3,938 4,200 5,355 8,269 9,188 10,106
6 5.5 4,950 6,188 6,600 8,415 12,994 14,438 15,881
All Species 8 7.25 6,525 8,156 8,700 11,093 17,128 19,031 20,934
10 9.25 8,325 10,406 11,100 14,153 21,853 24,281 26,709
12 11.25 10,125 12,656 13,500 17,213 26,578 29,531 32,484
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Table M4.5-2a ASD Column Capacity1,2,3,4,5 (P', P'x, P'y), Timbers 6-inch nominal thickness (5.5 inch dry dressed size), CD = 1.0.
1. P'x values are based on a column continuously braced against weak axis buckling. 2. P'y values are based on a column continuously braced against strong axis buckling. 3. To obtain LRFD capacity, see NDS Appendix N. 4. Tabulated values apply to members in a dry service condition, CM = 1.0; normal temperature range, Ct = 1.0; and unincised members, Ci = 1.0. 5. Column capacities are based on concentric axial loads only and pin-pin end conditions (Ke = 1.0 per NDS Appendix Table G1).
Column Capacity (lbs)
Select Structural No. 1 No. 2
6 x 6 6 x 8 6 x 6 6 x 8 6 x 6 6 x 8
6" width 8" width 6" width 8" width 6" width 8" width
Column (=5.5") (=7.5") (=5.5") (=7.5") (=5.5") (=7.5")
Species Length (ft) P' P'x P'y P' P'x P'y P' P'x P'y
Douglas Fir-
Larch
2 34,500 47,200 47,000 30,000 41,100 40,900 21,000 28,800 28,700
4 33,400 46,400 45,500 29,200 40,500 39,800 20,500 28,400 28,000
6 31,100 45,000 42,500 27,600 39,500 37,600 19,600 27,800 26,700
8 27,300 42,700 37,300 24,800 37,800 33,800 18,000 26,800 24,500
10 22,300 39,200 30,400 20,900 35,300 28,500 15,700 25,400 21,400
12 17,500 34,600 23,900 16,800 31,800 22,900 13,000 23,400 17,700
14 13,700 29,500 18,700 13,300 27,800 18,200 10,500 20,900 14,300
16 10,900 24,700 14,800 10,700 23,700 14,600 8,500 18,200 11,500
Hem-Fir
2 29,200 40,000 39,800 25,500 34,900 34,800 17,300 23,600 23,600
4 28,200 39,300 38,500 24,800 34,400 33,800 16,900 23,400 23,000
6 26,200 38,100 35,800 23,300 33,500 31,800 16,100 22,900 22,000
8 22,800 36,000 31,100 20,800 31,900 28,400 14,900 22,100 20,300
10 18,400 32,900 25,100 17,400 29,700 23,700 13,100 21,000 17,800
12 14,300 28,800 19,600 13,800 26,600 18,900 10,900 19,400 14,800
14 11,200 24,300 15,200 10,900 23,000 14,900 8,800 17,400 12,000
16 8,800 20,200 12,000 8,700 19,500 11,900 7,200 15,200 9,800
Southern Pine
2 28,500 39,000 38,900 24,800 33,900 33,800 15,800 21,600 21,500
4 27,700 38,500 37,800 24,200 33,500 33,000 15,500 21,400 21,100
6 26,200 37,500 35,700 23,100 32,800 31,500 15,000 21,000 20,400
8 23,500 35,900 32,100 21,200 31,600 28,900 14,100 20,500 19,200
10 19,900 33,500 27,100 18,400 29,900 25,100 12,700 19,700 17,400
12 16,000 30,200 21,800 15,200 27,500 20,700 11,000 18,500 15,000
14 12,700 26,400 17,300 12,300 24,500 16,700 9,200 17,100 12,500
16 10,100 22,400 13,800 9,900 21,300 13,500 7,600 15,300 10,300
Spruce-Pine-Fir
2 24,000 32,900 32,700 21,000 28,800 28,700 15,000 20,600 20,500
4 23,400 32,400 31,900 20,500 28,400 28,000 14,700 20,300 20,100
6 22,100 31,600 30,100 19,600 27,800 26,700 14,100 19,900 19,300
8 19,900 30,300 27,100 18,000 26,800 24,500 13,100 19,300 17,900
10 16,800 28,300 23,000 15,700 25,400 21,400 11,600 18,400 15,800
12 13,600 25,600 18,500 13,000 23,400 17,700 9,800 17,100 13,400
14 10,800 22,400 14,700 10,500 20,900 14,300 8,000 15,500 11,000
16 8,600 19,100 11,800 8,500 18,200 11,500 6,500 13,700 8,900
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Table M4.5-2b ASD Column Capacity (P', P'x, P'y), Timbers1,2,3,4,5 8-inch nominal thickness (7.5 inch dry dressed size), CD = 1.0.
1. P'x values are based on a column continuously braced against weak axis buckling. 2. P'y values are based on a column continuously braced against strong axis buckling. 3. To obtain LRFD capacity, see NDS Appendix N. 4. Tabulated values apply to members in a dry service condition, CM = 1.0; normal temperature range, Ct = 1.0; and unincised members, Ci = 1.0. 5. Column capacities are based on concentric axial loads only and pin-pin end conditions (Ke = 1.0 per NDS Appendix Table G1).
Column Capacity (lbs)
Select Structural No. 1 No. 2
8 x 8 8 x 10 8 x 8 8 x 10 8 x 8 8 x 10
8" width 10" width 8" width 10" width 8" width 10" width
Column (=7.5") (=9.5") (=7.5") (=9.5") (=7.5") (=9.5")
Species Length (ft) P' P'x P'y P' P'x P'y P' P'x P'y
Douglas Fir-
Larch
2 64,400 81,700 81,500 56,000 71,100 70,900 39,200 49,800 49,700
4 63,300 80,900 80,200 55,200 70,500 70,000 38,800 49,400 49,100
6 61,400 79,500 77,800 53,800 69,400 68,200 37,900 48,800 48,000
8 58,300 77,300 73,800 51,500 67,800 65,300 36,600 47,800 46,300
10 53,500 74,000 67,800 48,100 65,400 60,900 34,600 46,500 43,800
12 47,200 69,600 59,800 43,400 62,200 55,000 31,900 44,600 40,400
14 40,200 63,800 50,900 37,900 58,000 48,000 28,500 42,100 36,100
16 33,600 57,000 42,600 32,300 52,800 40,900 24,800 39,100 31,400
Hem-Fir
2 54,600 69,200 69,100 47,600 60,400 60,300 32,200 40,900 40,800
4 53,600 68,500 67,900 46,900 59,900 59,400 31,900 40,600 40,400
6 51,900 67,300 65,800 45,600 58,900 57,800 31,200 40,100 39,500
8 49,100 65,300 62,200 43,600 57,500 55,200 30,100 39,300 38,200
10 44,800 62,400 56,800 40,400 55,300 51,200 28,600 38,300 36,200
12 39,200 58,400 49,700 36,200 52,400 45,900 26,400 36,800 33,500
14 33,200 53,200 42,000 31,400 48,600 39,700 23,700 34,900 30,100
16 27,600 47,300 34,900 26,500 44,000 33,600 20,800 32,500 26,300
Southern Pine
2 53,200 67,500 67,400 46,200 58,600 58,600 29,400 37,300 37,300
4 52,500 66,900 66,500 45,700 58,200 57,900 29,200 37,100 36,900
6 51,100 65,900 64,700 44,700 57,500 56,600 28,700 36,800 36,300
8 48,900 64,400 62,000 43,100 56,300 54,600 27,900 36,200 35,400
10 45,700 62,200 57,800 40,700 54,700 51,600 26,800 35,400 34,000
12 41,200 59,100 52,200 37,500 52,500 47,500 25,300 34,400 32,000
14 35,900 55,000 45,500 33,400 49,600 42,400 23,300 33,000 29,500
16 30,600 50,200 38,800 29,100 46,000 36,800 20,900 31,300 26,500
Spruce-Pine-Fir
2 44,800 56,800 56,800 39,200 49,800 49,700 28,000 35,500 35,500
4 44,200 56,400 56,000 38,800 49,400 49,100 27,700 35,300 35,100
6 43,100 55,500 54,600 37,900 48,800 48,000 27,200 34,900 34,400
8 41,300 54,300 52,300 36,600 47,800 46,300 26,300 34,300 33,400
10 38,600 52,400 48,900 34,600 46,500 43,800 25,100 33,400 31,800
12 34,900 49,900 44,200 31,900 44,600 40,400 23,400 32,300 29,600
14 30,500 46,500 38,600 28,500 42,100 36,100 21,200 30,700 26,800
16 26,000 42,500 33,000 24,800 39,100 31,400 18,700 28,800 23,700
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Table M4.5-2c ASD Column Capacity (P', P'x, P'y), Timbers1,2,3,4,5 10-inch nominal thickness (9.5 inch dry dressed size), CD = 1.0.
1. P'x values are based on a column continuously braced against weak axis buckling. 2. P'y values are based on a column continuously braced against strong axis buckling. 3. To obtain LRFD capacity, see NDS Appendix N. 4. Tabulated values apply to members in a dry service condition, CM =1.0; normal temperature range, Ct =1.0; and unincised members, Ci =1.0. 5. Column capacities are based on concentric axial loads only and pin-pin end conditions (Ke = 1.0 per NDS Appendix Table G1).
Column Capacity (lbs)
Select Structural No. 1 No. 2
10 x 10 10 x 12 10 x 10 10 x 12 10 x 10 10 x 12
10" width 12 width 10" width 12 width 10" width 12 width
Column (=9.5") (=11.5") (=9.5") (=11.5") (=9.5") (=11.5")
Species Length (ft) P' P'x P'y P' P'x P'y P' P'x P'y
Douglas Fir-
Larch
2 103,500 125,400 125,200 90,000 109,000 109,000 63,000 76,400 76,300
4 102,500 124,600 124,000 89,300 108,400 108,000 62,600 76,000 75,700
6 100,700 123,100 121,900 87,900 107,400 106,400 61,800 75,300 74,800
8 97,900 121,000 118,500 85,900 105,800 103,900 60,600 74,400 73,300
10 93,800 117,900 113,500 82,900 103,500 100,300 58,800 73,100 71,200
12 88,100 113,800 106,700 78,800 100,500 95,400 56,500 71,300 68,400
14 80,800 108,300 97,800 73,400 96,600 88,900 53,400 69,100 64,600
16 72,200 101,500 87,500 66,900 91,600 81,000 49,500 66,200 59,900
Hem-Fir
2 87,700 106,300 106,200 76,500 92,700 92,600 51,800 62,700 62,700
4 86,800 105,600 105,100 75,800 92,100 91,800 51,400 62,400 62,200
6 85,200 104,300 103,100 74,600 91,200 90,300 50,800 61,900 61,500
8 82,700 102,400 100,100 72,800 89,700 88,100 49,800 61,200 60,300
10 79,000 99,600 95,700 70,100 87,700 84,800 48,500 60,100 58,700
12 73,900 95,900 89,500 66,400 85,000 80,400 46,600 58,800 56,400
14 67,400 91,000 81,600 61,500 81,500 74,500 44,200 57,000 53,500
16 59,900 84,900 72,500 55,700 77,000 67,500 41,100 54,700 49,800
Southern Pine
2 85,500 103,600 103,500 74,300 90,000 89,900 47,300 57,300 57,200
4 84,800 103,000 102,600 73,700 89,500 89,300 47,000 57,100 56,900
6 83,500 102,000 101,100 72,800 88,800 88,100 46,600 56,700 56,400
8 81,600 100,500 98,700 71,400 87,700 86,400 45,800 56,100 55,500
10 78,700 98,300 95,300 69,300 86,100 83,900 44,900 55,400 54,300
12 74,800 95,500 90,600 66,500 84,000 80,500 43,500 54,400 52,700
14 69,700 91,700 84,400 62,800 81,300 76,000 41,800 53,100 50,600
16 63,500 87,000 76,900 58,200 77,900 70,500 39,600 51,500 47,900
Spruce-Pine-Fir
2 72,000 87,200 87,200 63,000 76,400 76,300 45,000 54,500 54,500
4 71,400 86,800 86,400 62,600 76,000 75,700 44,700 54,300 54,200
6 70,400 85,900 85,200 61,800 75,300 74,800 44,200 53,900 53,500
8 68,700 84,600 83,200 60,600 74,400 73,300 43,400 53,300 52,600
10 66,400 82,900 80,400 58,800 73,100 71,200 42,400 52,400 51,300
12 63,200 80,500 76,500 56,500 71,300 68,400 40,900 51,300 49,500
14 59,000 77,400 71,400 53,400 69,100 64,600 38,900 49,900 47,100
16 53,800 73,500 65,200 49,500 66,200 59,900 36,500 48,100 44,100
AMERICAN WOOD COUNCIL
22 M4: SAWN LUMBER
Table M4.5-3a ASD Bending Member Capacity (M', CrM', V', and EI), Structural Lumber1,2
2-inch nominal thickness (1.5 inch dry dressed size), CD = 1.0, CL = 1.0.
Table M4.5-3b ASD Bending Member Capacity (M', CrM', V', and EI), Structural Lumber1,2
4-inch nominal thickness (3.5 inch dry dressed size), CD = 1.0, CL = 1.0.
1. Multiply tabulated M', CrM', and V' capacity by 1.728 to obtain LRFD capacity ( = 0.8). Tabulated EI is applicable for both ASD and LRFD. See NDS Appendix N for more information.
2. Tabulated values apply to members in a dry service condition, CM = 1.0; normal temperature range, Ct = 1.0; and unincised members, Ci = 1.0; members braced against buckling, CL = 1.0.
Select Structural No. 2
Size (b x d) M' Cr M' V' x 106 EI M' Cr M' V' x 106 EI
Nominal Actual (Single) (Repetitive) (Repetitive)
Species (in.) (in.) lb-in. lb-in. lbs lb-in.2 lb-in. lb-in. lbs lb-in.2
Douglas Fir-Larch
2 x 4 1.5 x 3.5 6,890 7,920 630 10 4,130 4,750 630 9
2 x 6 1.5 x 5.5 14,700 17,000 990 40 8,850 10,200 990 33
2 x 8 1.5 x 7.25 23,700 27,200 1,310 91 14,200 16,300 1,310 76
2 x 10 1.5 x 9.25 35,300 40,600 1,670 188 21,200 24,400 1,670 158
2 x 12 1.5 x 11.25 47,500 54,600 2,030 338 28,500 32,700 2,030 285
Hem-Fir
2 x 4 1.5 x 3.5 6,430 7,400 525 9 3,900 4,490 525 7
2 x 6 1.5 x 5.5 13,800 15,900 825 33 8,360 9,610 825 27
2 x 8 1.5 x 7.25 22,100 25,400 1,090 76 13,400 15,400 1,090 62
2 x 10 1.5 x 9.25 32,900 37,900 1,390 158 20,000 23,000 1,390 129
2 x 12 1.5 x 11.25 44,300 50,900 1,690 285 26,900 30,900 1,690 231
Southern Pine
2 x 4 1.5 x 3.5 8,730 10,000 613 10 4,590 5,280 613 9
2 x 6 1.5 x 5.5 19,300 22,200 963 37 9,450 10,900 963 33
2 x 8 1.5 x 7.25 30,200 34,800 1,270 86 15,800 18,100 1,270 76
2 x 10 1.5 x 9.25 43,900 50,400 1,620 178 22,500 25,800 1,620 158
2 x 12 1.5 x 11.25 60,100 69,100 1,970 320 30,800 35,500 1,970 285
Spruce-Pine-Fir
2 x 4 1.5 x 3.5 5,740 6,600 473 8 4,020 4,620 473 8
2 x 6 1.5 x 5.5 12,300 14,100 743 31 8,600 9,890 743 29
2 x 8 1.5 x 7.25 19,700 22,700 979 71 13,800 15,900 979 67
2 x 10 1.5 x 9.25 29,400 33,800 1,250 148 20,600 23,700 1,250 139
2 x 12 1.5 x 11.25 39,600 45,500 1,520 267 27,700 31,800 1,520 249
Select Structural No. 2
Size (b x d) M' Cr M' V' x 106 EI M' Cr M' V' x 106 EI
Nominal Actual (Single) (Repetitive) (Repetitive)
Species (in.) (in.) lb-in. lb-in. lbs lb-in.2 lb-in. lb-in. lbs lb-in.2
Douglas Fir-Larch
4 x 4 3.5 x 3.5 16,100 18,500 1,470 24 9,650 11,100 1,470 20
4 x 6 3.5 x 5.5 34,400 39,600 2,310 92 20,600 23,700 2,310 78
4 x 8 3.5 x 7.25 59,800 68,800 3,050 211 35,900 41,300 3,050 178
4 x 10 3.5 x 9.25 89,800 103,000 3,890 439 53,900 62,000 3,890 370
4 x 12 3.5 x 11.25 122,000 140,000 4,730 789 73,100 84,100 4,730 664
Hem-Fir
4 x 4 3.5 x 3.5 15,000 17,300 1,230 20 9,110 10,500 1,230 16
4 x 6 3.5 x 5.5 32,100 36,900 1,930 78 19,500 22,400 1,930 63
4 x 8 3.5 x 7.25 55,800 64,200 2,540 178 33,900 39,000 2,540 144
4 x 10 3.5 x 9.25 83,900 96,400 3,240 369 50,900 58,500 3,240 300
4 x 12 3.5 x 11.25 114,000 131,000 3,940 664 69,000 79,400 3,940 540
Southern Pine
4 x 4 3.5 x 3.5 20,400 23,400 1,430 23 10,700 12,300 1,430 20
4 x 6 3.5 x 5.5 45,000 51,700 2,250 87 22,100 25,400 2,250 78
4 x 8 3.5 x 7.25 77,600 89,200 2,960 200 40,500 46,600 2,960 178
4 x 10 3.5 x 9.25 113,000 129,000 3,780 416 57,600 66,300 3,780 369
4 x 12 3.5 x 11.25 154,000 177,000 4,590 748 79,200 91,100 4,590 664
Spruce-Pine-Fir
4 x 4 3.5 x 3.5 13,400 15,400 1,100 19 9,380 10,800 1,100 18
4 x 6 3.5 x 5.5 28,700 33,000 1,730 73 20,100 23,100 1,730 68
4 x 8 3.5 x 7.25 49,800 57,300 2,280 167 34,900 40,100 2,280 156
4 x 10 3.5 x 9.25 74,900 86,100 2,910 346 52,400 60,300 2,910 323
4 x 12 3.5 x 11.25 102,000 117,000 3,540 623 71,100 81,700 3,540 581
AMERICAN FOREST & PAPER ASSOCIATION
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Table M4.5-4a ASD Bending Member Capacity (M', V', and EI), Timbers1,2 6-inch nominal thickness (5.5 inch dry dressed size), CD = 1.0, CL = 1.0.
Table M4.5-4b ASD Bending Member Capacity (M', V', and EI), Timbers1,2 8-inch nominal thickness (7.5 inch dry dressed size), CD = 1.0, CL = 1.0.
1. Multiply tabulated M' and V' capacity by 1.728 to obtain LRFD capacity ( = 0.8). Tabulated EI is applicable for both ASD and LRFD. See NDS Appendix N for more information.
2. Tabulated values apply to members in a dry service condition, CM = 1.0; normal temperature range, Ct = 1.0; and unincised members, Ci = 1.0; members braced against buckling, CL = 1.0.
Select Structural No. 2
Size (b x d) M' V' x 106 EI M' V' x 106 EI
Nominal Actual (Single)
Species (in.) (in.) lb-in. lbs lb-in.2 lb-in. lbs lb-in.2
Douglas Fir-Larch
6 x 6 5.5 x 5.5 41,600 3,430 122 20,800 3,430 99
6 x 8 5.5 x 7.5 77,300 4,680 309 38,700 4,680 251
6 x 10 5.5 x 9.5 132,000 5,920 629 72,400 5,920 511
6 x 12 5.5 x 11.5 194,000 7,170 1,120 106,000 7,170 906
6 x 14 5.5 x 13.5 264,000 8,420 1,800 144,000 8,420 1,470
6 x 16 5.5 x 15.5 342,000 9,660 2,730 187,000 9,660 2,220
Hem-Fir
6 x 6 5.5 x 5.5 33,300 2,820 99 15,900 2,820 84
6 x 8 5.5 x 7.5 61,900 3,850 251 29,600 3,850 213
6 x 10 5.5 x 9.5 10,800 4,880 511 55,800 4,880 432
6 x 12 5.5 x 11.5 15,800 5,900 906 81,800 5,900 767
6 x 14 5.5 x 13.5 214,000 6,930 1,470 111,000 6,930 1,240
6 x 16 5.5 x 15.5 278,000 7,960 2,220 144,000 7,960 1,880
Southern Pine
6 x 6 5.5 x 5.5 41,600 3,330 114 23,600 3,330 92
6 x 8 5.5 x 7.5 77,300 4,540 290 43,800 4,540 232
6 x 10 5.5 x 9.5 124,000 5,750 589 70,300 5,750 472
Spruce-Pine-Fir
6 x 6 5.5 x 5.5 29,100 2,520 99 13,900 2,520 76
6 x 8 5.5 x 7.5 54,100 3,440 251 25,800 3,440 193
6 x 10 5.5 x 9.5 91,000 4,350 511 49,600 4,350 393
Select Structural No. 2
Size (b x d) M' V' x 106 EI M' V' x 106 EI
Nominal Actual (Single)
Species (in.) (in.) lb-in. lbs lb-in.2 lb-in. lbs lb-in.2
Douglas Fir-Larch
8 x 8 7.5 x 7.5 105,000 6,380 422 52,700 6,380 343
8 x 10 7.5 x 9.5 169,000 8,080 857 84,600 8,080 697
8 x 12 7.5 x 11.5 265,000 9,780 1,520 145,000 9,780 1,240
8 x 14 7.5 x 13.5 360,000 11,500 2,460 197,000 11,500 2,000
8 x 16 7.5 x 15.5 467,000 13,200 3,720 255,000 13,200 3,030
Hem-Fir
8 x 8 7.5 x 7.5 84,400 5,250 343 40,400 5,250 290
8 x 10 7.5 x 9.5 135,000 6,650 697 64,900 6,650 589
8 x 12 7.5 x 11.5 215,000 8,050 1,240 112,000 8,050 1,050
8 x 14 7.5 x 13.5 292,000 9,450 2,000 152,000 9,450 1,690
8 x 16 7.5 x 15.5 379,000 10,900 3,030 197,000 10,900 2,560
Southern Pine 8 x 8 7.5 x 7.5 105,000 6,190 396 59,800 6,190 316
8 x 10 7.5 x 9.5 169,000 7,840 804 95,900 7,840 643
Spruce-Pine-Fir 8 x 8 7.5 x 7.5 73,800 4,690 343 35,200 4,690 264
8 x 10 7.5 x 9.5 118,000 5,940 697 56,400 5,940 536
AMERICAN WOOD COUNCIL
24 M4: SAWN LUMBER
Table M4.5-4d ASD Bending Member Capacity (M', V', and EI), Timbers1,2 Nominal dimensions > 10 inch (actual = nominal – 1/2 inch), CD = 1.0, CL = 1.0.
Table M4.5-4c ASD Bending Member Capacity (M', V', and EI), Timbers1,2 10-inch nominal thickness (9.5 inch dry dressed size), CD = 1.0, CL = 1.0.
1. Multiply tabulated M' and V' capacity by 1.728 to obtain LRFD capacity ( = 0.8). Tabulated EI is applicable for both ASD and LRFD. See NDS Appendix N for more information.
2. Tabulated values apply to members in a dry service condition, CM = 1.0; normal temperature range, Ct = 1.0; and unincised members, Ci = 1.0; members braced against buckling, CL = 1.0.
Select Structural No. 2
Size (b x d) M' V' x 106 EI M' V' x 106 EI
Nominal Actual (Single)
Species (in.) (in.) lb-in. lbs lb-in.2 lb-in. lbs lb-in.2
Douglas Fir-Larch
10 x 10 9.5 x 9.5 214,000 10,200 1,090 107,000 10,200 882
10 x 12 9.5 x 11.5 314,000 12,400 1,930 157,000 12,400 1,570
10 x 14 9.5 x 13.5 456,000 14,500 3,120 249,000 14,500 2,530
10 x 16 9.5 x 15.5 592,000 16,700 4,720 324,000 16,700 3,830
10 x 18 9.5 x 17.5 744,000 18,800 6,790 407,000 18,800 5,520
10 x 20 9.5 x 19.5 913,000 21,000 9,390 499,000 21,000 7,630
Hem-Fir
10 x 10 9.5 x 9.5 171,000 8,420 882 82,200 8,420 747
10 x 12 9.5 x 11.5 251,000 10,200 1,570 120,000 10,200 1,320
10 x 14 9.5 x 13.5 370,000 12,000 2,530 192,000 12,000 2,140
10 x 16 9.5 x 15.5 418,000 13,700 3,830 250,000 13,700 3,240
10 x 18 9.5 x 17.5 604,000 15,500 5,520 314,000 15,500 4,670
10 x 20 9.5 x 19.5 742,000 17,300 7,630 385,000 17,300 6,460
Southern Pine
10 x 10 9.5 x 9.5 214,000 9,930 1,020 121,000 9,930 815
10 x 12 9.5 x 11.5 314,000 12,000 1,810 178,000 12,000 1,440
10 x 14 9.5 x 13.5 427,000 14,100 2,920 242,000 14,100 2,340
Spruce-Pine-Fir
10 x 10 9.5 x 9.5 150,000 7,520 882 71,000 7,520 679
10 x 12 9.5 x 11.5 220,000 9,100 1,570 105,000 9,100 1,200
10 x 14 9.5 x 13.5 313,000 10,700 2,530 171,000 10,700 1,950
Select Structural No. 2
Size (b x d) M' V' x 106 EI M' V' x 106 EI
Nominal Actual (Single)
Species (in.) (in.) lb-in. lbs lb-in.2 lb-in. lbs lb-in.2
Douglas Fir-Larch
12 x 12 11.5 x 11.5 380,000 15,000 2,330 190,000 15,000 1,890
14 x 14 13.5 x 13.5 607,000 20,700 4,430 304,000 20,700 3,600
16 x 16 15.5 x 15.5 905,000 27,200 7,700 452,000 27,200 6,250
18 x 18 17.5 x 17.5 1,280,000 34,700 12,500 642,000 34,700 10,200
20 x 20 19.5 x 19.5 1,760,000 43,100 19,300 878,000 43,100 15,700
Hem-Fir
12 x 12 11.5 x 11.5 304,000 12,300 1,890 146,000 12,300 1,600
14 x 14 13.5 x 13.5 486,000 17,000 3,600 233,000 17,000 3,040
16 x 16 15.5 x 15.5 724,000 22,400 6,250 347,000 22,400 5,290
18 x 18 17.5 x 17.5 1,030,000 28,600 10,200 493,000 28,600 8,600
20 x 20 19.5 x 19.5 1,410,000 35,500 15,700 673,000 35,500 13,300
Southern Pine 12 x 12 11.5 x 11.5 380,000 14,500 2,190 215,000 14,500 1,750
14 x 14 13.5 x 13.5 607,000 20,000 4,150 344,000 20,000 3,320
Spruce-Pine-Fir 12 x 12 11.5 x 11.5 266,000 11,000 1,890 127,000 11,000 1,460
14 x 14 13.5 x 13.5 425,000 15,200 3,600 202,000 15,200 2,770
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Tension Capacity Tables
The general design equation for tension members is:
T T
where: T = tension force due to design loads T = allowable tension capacity
Example M4.6-1: Application – tension member Species: Hem-Fir Size: 2 x 6 (1.5 in. by 5.5 in.) Grade: 1650f-1.5E MSR Ft: 1,020 psi A: 8.25 in.2
Tension Capacity
1,020 8.25
8,415 lbs
tT F A
Column Capacity Tables
The general design equation is:
where: P = compressive force due to design loads P = allowable compression capacity
Axial Capacity
p AF*c where:
2 * * *
cE c cE c cE c P
1 F / F 1 F / F F / F C
2c 2c c
0.822 cE 2
e
E F
/ d
and: F*c = reference compression design value
multiplied by all applicable adjustment factors except Cp
A = area CP = column stability factor Fc = adjusted parallel-to-grain compression
design value Emin = adjusted modulus of elasticity for column
stability calculations c = 0.8 for solid sawn members
Example M4.6-2: Application – simple column Species: Douglas Fir-Larch Size: 6 x 8 (5.5 in. by 7.5 in.) by 12 ft. Grade: No. 1 (dry) Posts and Timbers F*c: 1,000 psi Emin : 580,000 psi A: 41.25 in2
Column Capacity – x-axis
2
0.822
0.822 580,000
144/7.5
1,293 psi
min cE 2
e x
E F
/ d
2
1+ 1,293/1,000
2 0.8
1+ 1,293/1,000 1,293/1,000 2 0.8 0.8
0.772
PxC
0.772 41.25 1,000
= 31,845 lb. xP
M4.6 Examples of Capacity Table Development
AMERICAN WOOD COUNCIL
26 M4: SAWN LUMBER
Column Capacity – y-axis
2
0.822
0.822 580,000
144/5.5
= 696 psi
min cE 2
e y
E F
/ d
2
1+ 696/1,000
2 0.8
1+ 696/1,000 696/1,000 2 0.8 0.8
= 0.556
PyC
0.556 41.25 1,000
= 22,952 lb xP
Bending Member Capacity Tables
where: M = moment due to design loads M = allowable moment capacity
where: V = shear force due to design loads V = allowable shear capacity
Example M4.6-3: Application – structural lumber Species: Douglas Fir-Larch Size: 2 x 6 (1.5 in. by 5.5 in.) Grade: No. 2 CF: 1.3 (size factor) Cr: 1.15 (repetitive member factor) Fb: 900 psi Fv: 180 psi E: 1,600,000 psi A: 8.25 in.2
S: 7.56 in.3
I: 20.80 in.4
Moment Capacity
= 900 1.3 1.15 7.56
= 10,172 lb - in.
r b F rC M F C C S
Shear Capacity 2 3
2 = 180 8.25
3 = 990 lb
vV F A
Flexural Stiffness
(1,600,000)(20.80) = 33 × 106 lb - in.2
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M5: STRUCTURAL GLUED LAMINATED TIMBER
M5.1 General 28
M5.2 Reference Design Values 30
M5.3 Adjustment of Reference Design Values 31
M5.4 Special Design Considerations 32
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28 M5: STRUCTURAL GLUED LAMINATED TIMBER
M5.1 General
Figure M5.1-1 Unbalanced and Balanced Layup Combinations
Products Description
Structural glued laminated timber (glulam) is a struc- tural member glued up from suitably selected and prepared pieces of wood either in a straight or curved form with the grain of all of the pieces parallel to the longitudinal axis of the member. The reference design values given in the NDS Supplement are applicable only to structural glued laminated timber members produced in accordance with American National Standard for Wood Products — Struc- tural Glued Laminated Timber, ANSI/AITC A190.1.
Structural glued laminated timber members are pro- duced in laminating plants by gluing together dry lumber, normally of 2-inch or 1-inch nominal thickness, under controlled temperature and pressure conditions. Members
be produced having superior characteristics of strength, serviceability, and appearance. Structural glued lami- nated timber beams are manufactured with the strongest laminations on the bottom and top of the beam, where the greatest tension and compression stresses occur in bending.
by placing higher grade lumber in zones that have higher stresses and lumber with less structural quality in lower stressed zones.
Structural glued laminated timber members are manu- factured from several softwood species, primarily Douglas
spruce, western woods, Alaska cedar, Durango pine, and California redwood. In addition, several hardwood species, including red oak, red maple, and yellow poplar, are also used. Standard structural glued laminated timber sizes are given in the NDS Supplement. Any length, up to the maximum length permitted by transportation and handling restrictions, is available.
A structural glued laminated timber member can be manufactured using a single grade or multiple grades of lumber, depending on intended use. In addition, a mixed- species structural glued laminated timber member is also possible. When the member is intended to be primarily loaded either axially or in bending with the loads acting parallel to the wide faces of the laminations, a single grade combination is recommended. On the other hand, a multiple grade combination provides better cost-effec- tiveness when the member is primarily loaded in bending due to loads applied perpendicular to the wide faces of the laminations.
On a multiple grade combination, a structural glued laminated timber member can be produced as either a
balanced or unbalanced combination, depending on the geometrical arrangement of the laminations about the mid-depth of the member. As shown in Figure M5.1-1, a balanced combination is symmetrical about the mid-depth, so both faces have the same reference bending design value. Unbalanced combinations are asymmetrical and when used as a beam, the face with a lower allowable bending stress is stamped as TOP. The balanced combina- tion is intended for use in continuous or cantilevered over supports to provide equal capacity in both positive and negative bending. Whereas the unbalanced combination is primarily for use in simple span applications, they can also be used for short cantilever applications (cantilever less than 20% of the back span) or for continuous span applications when the design is controlled by shear or
Structural glued laminated timber members can be used as primary or secondary load-carrying components in structures. Table M5.1-1 lists economical spans for selected timber framing systems using structural glued laminated timber members in buildings. Other common uses of structural glued laminated timber members are for utility structures, pedestrian bridges, highway bridges, railroad bridges, marine structures, noise barriers, and towers. Table M5.1-1 may be used for preliminary design purposes to determine the economical span ranges for the selected framing systems. However, all systems require a
No. 2D Tension Lam No. 2 No. 1 No. 2 No. 2 No. 3 No. 3 No. 3 No. 3 No. 3 No. 3 No. 2 No. 2 No. 1 No. 1
Tension Lam Tension Lam Unbalanced Balanced
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Table M5.1-1 Economical Spans for Structural Glued Laminated Timber Framing Systems
Type of Framing System Economical Spans (ft)
ROOF Simple Span Beams
Straight or slightly cambered 10 to 100 Tapered, double tapered-pitched, or curved
25 to 105
Cantilevered Beams (Main span) up to 90 Continuous Beams (Interior spans) 10 to 50 Girders 40 to 100 Three-Hinged Arches
Gothic 40 to 100 Tudor 40 to 140 A-Frame 20 to 100 Three-centered, Parabolic, or Radial 40 to 250
Two-Hinged Arches Radial or Parabolic 50 to 200
Trusses (Four or more ply chords) Flat or parallel chord 50 to 150 Triangular or pitched 50 to 150 Bowstring (Continuous chord) 50 to 200
Trusses (Two or three ply chords) Flat or parallel chord 20 to 75 Triangular or pitched 20 to 75
Tied arches 50 to 200 Dome structures 200 to 500+
FLOOR Simple Span Beams 10 to 40 Continuous Beams (Individual spans) 10 to 40 HEADERS Windows and Doors < 10 Garage Doors 9 to 18
Appearance Classifications
Structural glued laminated timber members are
Premium, Architectural, Industrial, and Framing. Premium and Architectural beams are higher in appearance qualities
in concealed applications or in construction where appear-
typically used for headers and other concealed applications in residential construction. Design values for structural glued laminated timber members are independent of the
For more information and detailed descriptions of these
APA EWS Technical Note Y110 or AITC Standard 110.
Availability
Structural glued laminated timber members are avail- able in both custom and stock sizes. Custom beams are
while stock beams are made in common dimensions, shipped to distribution yards, and cut to length when the beam is ordered. Stock beams are available in virtually every major metropolitan area. Although structural glued laminated timber members can be custom fabricated to
best economy is generally realized by using standard-size members as noted in the NDS Supplement. When in doubt, the designer is advised to check with the structural glued laminated timber supplier or manufacturer concerning the
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30 M5: STRUCTURAL GLUED LAMINATED TIMBER
M5.2 Reference Design Values
Figure M5.2-1 Loading in the X-X and Y-Y Axes
Reference design values of structural glued laminated timber are affected by the layup of members composed of various grades of lumber as well as the direction of ap- plied bending forces. As a result, different design values are assigned for structural glued laminated timber used primarily in bending (NDS Supplement Table 5A) and primarily in axial loading (NDS Supplement Table 5B). The reference design values are used in conjunction with the dimensions provided in Table 1C (western species) and Table 1D (southern pine) of the NDS Supplement, but are applicable to any size of structural glued laminated timber
M5.3 are applied. Reference design values are given in NDS Supple-
ment Table 5A for bending about the X-X axis (see Figure M5.2-1). Although permitted, axial loading or bending
in using the structural glued laminated timber combina- tions given in NDS Supplement Table 5A. In such cases, the designer should select structural glued laminated timber from NDS Supplement Table 5B. Similarly, structural glued laminated timber combinations in NDS Supplement Table
about the X-X axis. The reference design values given in NDS Supplement
Tables 5A and 5B are based on use under normal dura- tion of load (10 years) and dry conditions (less than 16% moisture content). When used under other conditions, see NDS Chapter 5 for adjustment factors. The reference bending design values are based on members loaded as simple beams. When structural glued laminated timber is used in continuous or cantilevered beams, the reference bending design values given in NDS Supplement Table 5A for compression zone stressed in tension should be used for the design of stress reversal.
X-X Axis Loading Y-Y Axis Loading
XX
X
X
Y Y
Y
Y
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M5.3 Adjustment of Reference Design Values The adjustment factors provided in the NDS are for
- tion effects. These factors shall be used to modify the
the limits of the reference conditions given in the NDS. Adjustment factors unique to structural glued laminat-
ed timber include the volume factor, CV, and the curvature factor, Cc NDS.
Bending Member Example For straight, laterally supported bending members
loaded perpendicular to the wide face of the laminations and used in a normal building environment (meeting the reference conditions of NDS 2.3 and 5.3), the adjusted design values reduce to:
For ASD: Fb = Fb CD CV
Fv = Fv CD
Fc = Fc Cb
E = E
Emin = Emin
For LRFD: Fb = Fb CV KF b
Fv = Fv KF v
Fc = Fc Cb KF c
E = E
Emin = Emin KF s
Axially Loaded Member Example For axially loaded members used in a normal building
environment (meeting the reference conditions of NDS 2.3 and 5.3) designed to resist tension or compression loads, the adjusted tension or compression design values reduce to:
For ASD: Fc = Fc CD CP
Ft = Ft CD
Emin = Emin
For LRFD: Fc = Fc CP KF c
Ft = Ft KF t
Emin = Emin KF s
Table M5.3-1 Applicability of Adjustment Factors for Structural Glued Laminated Timber1
Allowable Stress Design Load and Resistance Factor Design Fb b CD CM Ct CL CV Cfu Cc Fb b CM Ct CL CV Cfu Cc KF b Ft t CD CM Ct Ft t CM Ct KF t Fv v CD CM Ct Fv v CM Ct KF v Fc c CM Ct Cb Fc c CM Ct Cb KF c Fc c CD CM Ct CP Fc c CM Ct CP KF c
M Ct M Ct Emin min CM Ct Emin min CM Ct KF s
1. The beam stability factor, CL, shall not apply simultaneously with the volume factor, CV, for structural glued laminated timber bending members (see NDS 5.3.6). Therefore, the lesser of these adjustment factors shall apply.
To generate member design capacities, reference design values for structural glued laminated timber are multiplied by adjustment factors and section properties per Chapter M3. Applicable adjustment factors for structural
NDS 5.3. Table M5.3-1 shows the applicability of adjustment factors for structural glued laminated timber in a slightly different format for the designer.
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32 M5: STRUCTURAL GLUED LAMINATED TIMBER
M5.4 Special Design Considerations
Table M5.4-1 Average Specific Gravity and Weight Factor
Structural glued laminated timber members often are manufactured using different species at different portions of the cross section. In this case the weight of the structural glued laminated timber may be computed by the sum of the products of the cross-sectional area and the weight factor for each species.
Dimensional Changes
See M4.4 for information on calculating dimensional changes due to moisture or temperature.
Durability
See M4.4 for information on detailing for durability.
Weight Factor2
Species Combination 1 12% 15% 19% 25% California Redwood (close grain) 0.44 0.195 0.198 0.202 0.208 Douglas Fir-Larch 0.50 0.235 0.238 0.242 0.248 Douglas Fir (South) 0.46 0.221 0.225 0.229 0.235 Eastern Spruce 0.41 0.191 0.194 0.198 0.203 Hem-Fir 0.43 0.195 0.198 0.202 0.208 Red Maple 0.58 0.261 0.264 0.268 0.274 Red Oak 0.67 0.307 0.310 0.314 0.319 Southern Pine 0.55 0.252 0.255 0.259 0.265 Spruce-Pine-Fir (North) 0.42 0.195 0.198 0.202 0.208 Yellow Poplar 0.43 0.213 0.216 0.220 0.226 1. Specific gravity is based on weight and volume when ovendry. 2. Weight factor shall be multiplied by net cross-sectional area in in.2 to obtain weight in pounds per lineal foot.
General
The section contains information concerning physical properties of structural glued laminated timber members
temperature. In addition to designing to accommodate dimensional
performance, which is discussed in Chapter M16.
Specific Gravity
of the most common wood species used for structural glued laminated timber. These values are used in determining various physical and connection properties. Further, weight factors are provided at four moisture contents. When the cross-sectional area (in.2) is multiplied by the appropriate weight factor, it provides the weight of the structural glued laminated timber member per linear foot of length. For other moisture contents, the tabulated weight factors can be interpolated or extrapolated.
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M6: ROUND TIMBER POLES AND PILES
M6.1 General 34
M6.2 Reference Design Values 34
M6.3 Adjustment of Reference Design Values 35
M6.4 Special Design Considerations 36
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34 M6: ROUND TIMBER POLES AND PILES
M6.1 General Product Information
Timber poles are used extensively in post-frame con- struction and are also used architecturally. This Chapter is not for use with poles used in the support of utility lines. Timber piles are generally used as part of foundation systems.
Timber poles and piles offer many advantages rela- tive to competing materials. As with other wood products, timber poles and piles offer the unique advantage of being the only major construction material that is a renewable resource.
Common Uses
Timber poles are used extensively in post-frame con- struction and are also used architecturally. This Chapter is not for use with poles used in the support of utility lines. Timber piles are generally used as part of founda- tion systems.
M6.2 Reference Design Values General
The tables in NDS Chapter 6 provide reference design values for timber pole and pile members. These reference design values are used when manual calculation of member strength is required and shall be used in conjunction with
NDS Chapter 6.
Pole Reference Design Values
Reference design values for poles are provided in NDS Table 6B. These values, with the exception of Fc, are applicable for all locations in the pole. The Fc values
with NDS 6.3.9. Reference design values are applicable for wet ex-
posure and for poles treated with a steam conditioning or Boultonizing process. For poles that are not treated, or are air-dried or kiln-dried prior to treating, the factors in NDS 6.3.5 shall be applied.
Timber poles and piles offer many advantages rela- tive to competing materials. As with other wood products, timber poles and piles offer the unique advantage of being the only major construction material that is a renewable resource.
Availability
Timber piles are typically available in four species:
pine. However, local pile suppliers should be contacted because availability is dependent upon geographic loca- tion.
Timber poles are supplied to the utility industry in a variety of grades and species. Because these poles are graded according to ANSI 05.1, - sions for Wood Poles, they must be regraded according to ASTM D3200 if they are to be used with the NDS.
Pile Reference Design Values
Reference design values for piles are provided in NDS Table 6A. These values, with the exception of Fc, are applicable at any location along the length of the pile. The tabulated Fc southern pine may be increased for locations other than the tip as provided by NDS 6.3.9.
Reference design values are applicable for wet expo- sures. These tabulated values are given for air-dried piles treated with a preservative using a steam conditioning or Boultonizing process. For piles that are not treated, or are air-dried or kiln-dried prior to treating, the factors in NDS 6.3.5 shall be applied.
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M6.3 Adjustment of Reference Design Values To generate member design capacities, reference
design values are multiplied by adjustment factors and section properties. Adjustment factors unique to round timber poles and piles include the untreated factor, Cu, the critical section factor, Ccs, and the single pile factor, Csp.
NDS. To generate member design capacities, reference de-
sign values for round timber poles and piles are multiplied by adjustment factors and section properties per Chapter M3. Applicable adjustment factors for round timber poles
NDS 6.3. Table M6.3-1 shows the applicability of adjustment factors for round timber poles and piles in a slightly different format for the designer.
Axially Loaded Pole or Pile Example
For single, axially loaded, treated poles or piles, fully laterally supported in two orthogonal directions, used in a normal environment (meeting the reference conditions of NDS 2.3 and 6.3), designed to resist compression loads only, and less than 13.5" in diameter, the adjusted compres- sion design values reduce to:
For ASD: Fc = Fc CD Csp
For LRFD: Fc = Fc Csp KF c
Allowable Stress Design Load and Resistance Factor Design Fc = Fc CD Ct Cu CP Ccs Csp Fc = Fc Ct Cu CP Ccs Csp KF c Fb = Fb CD Ct Cu CF Csp Ft = Ft Ct Cu CF Csp KF b Fv = Fv CD Ct Cu Fv = Fv Ct Cu KF v Fc = Fc CD1 Ct Cu Cb Fc = Fc Ct Cu Cb KF c E = E Ct E = E Ct Emin = Emin Ct Emin = Emin Ct KF s 1. The CD factor shall not apply to compression perpendicular to grain for poles.
Table M6.3-1 Applicability of Adjustment Factors for Round Timber Poles and Piles1
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36 M6: ROUND TIMBER POLES AND PILES
M6.4 Special Design Considerations With proper detailing and protection, timber poles and
piles can perform well in a variety of environments. One key to proper detailing is planning for the natural shrink- age and swelling of wood products as they are subjected to various drying and wetting cycles. While moisture changes have the largest impact on product dimensions, some designs must also check the effects of temperature. See M4.4 for design information on dimensional changes due to moisture and temperature.
Durability issues related to piles are generally both more critical and more easily accommodated. Since piles are in constant ground contact, they cannot be “insulated” from contact with moisture – thus, the standard reference condition for piles is preservatively treated. The impor- tance of proper treatment processing of piles cannot be overemphasized. See M4.4 for more information about durability.
In addition to designing to accommodate dimensional
performance, which is discussed in Chapter M16.
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M7: PREFABRICATED WOOD I-JOISTS
M7.1 General 38
M7.2 Reference Design Values 38
M7.3 Adjustment of Reference Design Values 40
M7.4 Special Design Considerations 41
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38 M7: PREFABRICATED WOOD I-JOISTS
M7.1 General Product Information
I-joists are exceptionally stiff, lightweight, and ca- pable of long spans. Holes may be easily cut in the web according to manufacturer’s recommendations, allowing ducts and utilities to be run through the joist. I-joists are dimensionally stable and uniform in size, with no crown.
proper length using conventional methods and tools. Manufacturing of I-joists utilizes the geometry of the
cross section and high strength components to maximize
manufactured from solid sawn lumber or structural com- posite lumber, while webs typically consist of plywood
materials, along with high-quality exterior adhesives and state of the art quality control procedures, result in an ex- tremely consistent product that maximizes environmental
Wood I-joists are produced as proprietary products which are covered by code acceptance reports by one or all of the model building codes. Acceptance reports and product literature should be consulted for current design information.
Common Uses
Prefabricated wood I-joists are widely used as a fram- ing material for housing in North America. I-joists are made in different grades and with various processes and can be utilized in various applications. Proper design is required to optimize performance and economics.
use in commercial and industrial construction. The high strength, stiffness, wide availability, and cost saving at- tributes make them a viable alternative in most low-rise construction projects.
and roof joists in conventional construction. In addition, I-joists are used as studs where long lengths and high strengths are required.
Availability
- tion projects, consideration should be given to the size and the required strength of the I-joist. Sizes vary with each individual product. The best source of this information is your local lumber supplier, distribution center, or I-joist manufacturer. Proper design is facilitated through the use
available from I-joist manufacturers.
Introduction to Design Values
As stated in NDS 7.2, each wood I-joist manufacturer develops its own proprietary design values. The deriva- tion of these values is reviewed by the applicable building code authority. Since materials, manufacturing processes, and product evaluations may differ between the various manufacturers, selected design values are only appropriate
To generate the design capacity of a given product, the manufacturer of that product evaluates test data. The design capacity is then determined per ASTM D5055.
The latest model building code agency evaluation re- ports are a reliable source for wood I-joist design values. These reports list accepted design values for shear, mo- ment, stiffness, and reaction capacity based on minimum bearing. In addition, evaluation reports note the limitations on web holes, concentrated loads, and requirements for web stiffeners.
M7.2 Reference Design Values Bearing/Reaction Design
NDS Chapter 7 to obtain adjusted capacity values.
Bearing lengths at supports often control the design capacity of an I-joist. Typically minimum bearing lengths are used to establish design parameters. In some cases
installation. Increased bearing length means that the joist can support additional loading, up to the value limited by the shear capacity of the web material and web joint. Both interior and exterior reactions must be evaluated.
Use of web stiffeners may be required and typically increases the bearing capacity of the joist. Correct in-
Additional loading from walls above will load the joist in bearing, further limiting the capacity of the joist if proper
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end detailing is not followed. Additional information on
Adjusted bearing capacities, Rr are determined in the same empirical fashion as is allowable shear.
Shear Design
At end bearing locations, critical shear is the verti- cal shear at the ends of the design span. The practice of neglecting all uniform loads within a distance from the end support equal to the joist depth, commonly used for other wood materials, is not applicable to end supports for wood I-joists. At locations of continuity, such as interior supports of multi-span I-joists, the critical shear location for several wood I-joist types is located a distance equal to the depth of the joist from the centerline of bearing (uniform loads only). A cantilevered portion of a wood I-joist is generally not considered a location of continuity (unless the cantilever length exceeds the joist depth) and vertical shear at the cantilever bearing is the critical shear. Individual manufacturers, or the appropriate evaluation reports, should be consulted for reference to shear design at locations of continuity.
Often, the adjusted shear capacities, Vr', are based on
or the installation of web stiffeners or bearing blocks.
Moment Design
Adjusted moment capacities, Mr , of I-joists are deter- mined from empirical testing of a completely assembled joist or by engineering analysis supplemented by tension
jointed material, the allowable tension value is the lesser of the joint capacity or the material capacity.
Because flanges of a wood I-joist can be highly -
larly, excessive nailing or the use of improper nail sizes
The manufacturer should be contacted when evaluating a
Deflection Design
Wood I-joists, due to their optimized web materials, -
under uniform load is shown in Equation M7.2-1.
5 384
4 2w EI
w k
(M7.2-1)
Individual manufacturers provide equations in a simi- lar format. Values for use in the preceding equation can be found in the individual manufacturer’s evaluation reports. For other load and span conditions, an approximate answer
equations adjusted as follows:
1 384 5
EI k2
where: w = uniform load in pounds per lineal inch
= design span, in.
E I = joist moment of inertia times flange modulus of elasticity
k = shear deflection coefficient
Since wood I-joists can have long spans, the model
I-joist manufacturers recommend using stiffer criteria,
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M7.3 Adjustment of Reference Design Values General
Member design capacity is the product of reference design values and adjustment factors. Reference design values for I-joists are discussed in M7.2.
The design values listed in the evaluation reports are generally applicable to dry use conditions. Less typical conditions, such as high moisture, high temperatures, or
The user is cautioned that manufacturers may not permit the use of some applications and/or treatments. Unauthorized treatments can void a manufacturer’s war-
Lateral Stability
The design values contained in the evaluation reports assume continuous lateral restraint of the joist’s compres- sion edge and lateral torsional restraint at the support locations. Lateral restraint is generally provided by dia- phragm sheathing or bracing spaced at 16" on center or
Applications without continuous lateral bracing will generally have reduced moment design capacities. The reduced capacity results from the increased potential for
- tion with individual manufacturers is recommended for all applications without continuous lateral bracing.
Special Loads or Applications
primarily as joists to resist bending loads supported at
web holes, special connections, or other unusual condi- tions should be evaluated only with the assistance of the individual wood I-joist manufacturers.
Bending Member Example For fully laterally supported bending members loaded
in strong axis bending and used in a normal building en- vironment (meeting the reference conditions of NDS 2.3 and 7.3), the adjusted design values reduce to:
For ASD: Mr = Mr CD
Vr = Vr CD
Rr = Rr CD
E I = E I K = K
For LRFD: Mr = Mr KF b
Vr = Vr KF v
Rr = Rr KF v
EI = EI K = K
Table M7.3-1 Applicability of Adjustment Factors for Prefabricated Wood I-Joists
Allowable Stress Design Load and Resistance Factor Design Mr r CD CM Ct CL Cr Mr r CM Ct CL Cr KF b Vr r CD CM Ct Vr r CD CM Ct KF v Rr r CD CM Ct Rr r CM Ct KF v
M Ct M Ct EImin min CM Ct EImin min CM Ct KF s
pressure impregnated chemical treatments, typically result in strength and stiffness adjustments different from those used for sawn lumber. NDS 7.3 outlines adjustments to design values for I-joists; however, individual wood I-joist manufacturers should be consulted to verify appropriate adjustments. Table M7.3-1 shows the applicability of adjustment factors for prefabricated wood I-joists in a slightly different format for the designer.
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M7.4 Special Design Considerations
Figure M7.4-1 Design Span Determination
Introduction
The wood I-joist is similar to conventional lumber in that it is based on the same raw materials, but differs in how the material is composed. For this reason, conventional lumber design practices are not always compatible with
wood I-joist. Designers using wood I-joists should develop solutions in accordance with the following guidelines.
Durability issues cannot be overemphasized. See M4.4 for more information about durability.
-
performance, which is discussed in NDS Chapter 16.
Design Span
The design span used for determining critical shears
faces of support plus one-half the minimum required bearing on each end (see Figure M7.4-1). For most wood I-joists, the minimum required end bearing length varies from 1½" to 3½" (adding 2" to the clear span dimension is a good estimate for most applications). At locations of continuity over intermediate bearings, the design span is measured from the centerline of the intermediate support to the face of the bearing at the end support, plus one-half the minimum required bearing length. For interior spans of a continuous joist, the design span extends from centerline to centerline of the intermediate bearings.
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Load Cases
Most building codes require consideration of a critical distribution of loads. Due to the long length and continuous span capabilities of the wood I-joist, these code provisions have particular meaning. Considering a multiple span member, the following design load cases should be considered:
All spans with total loads Alternate span loading Adjacent span loading Partial span loading (joists with holes) Concentrated load provisions (as occurs)
A basic description of each of these load cases fol- lows:
Total loads on all spans – This load case involves placing all live and dead design loads on all spans simul- taneously.
Alternate span loading – This load case places the L, LR, S, or R load portion of the design loads on every
pattern results in the removal of the live loads from all even numbered spans. The second pattern removes live loads from all odd numbered spans. For roof applications, some building codes require removal of only a portion of the live loads from odd or even numbered spans. The alternate span load case usually generates maximum end
Illustrations of this type of loading are shown in Figure M7.4-2.
Adjacent span loading – This load case (see Figure M7.4-2) removes L, LR, S or R loads from all but two adjoining spans. All other spans, if they exist, are loaded with dead loads only. Depending on the number of spans involved, this load case can lead to a number of load pat- terns. All combinations of adjacent spans become separate loadings. This load case is used to develop maximum shears and reactions at internal bearing locations.
Partial span loading – This load case involves ap- plying L, LR, S or R loads to less than the full length of a span (see Figure M7.4-2). For wood I-joists with web holes, this case is used to develop shear at hole locations. When this load case applies, uniform L, LR, S, R load is applied only from an adjacent bearing to the opposite edge of a rectangular hole (centerline of a circular hole). For each hole within a given span, there are two corresponding load cases. Live loads other than the uniform application load, located within the span containing the hole, are also applied simultaneously. This includes all special loads such as point or tapered loads.
Concentrated load provisions – Most building codes have a concentrated load (live load) provision in addition to standard application design loads. This load case con- siders this concentrated load to act in combination with
roof. Usually, this provision applies to non-residential construction. An example is the “safe” load applied over
helps insure the product being evaluated has the required shear and moment capacity throughout it’s entire length and should be considered when analyzing the effect of web holes.
A properly designed multiple span member requires numerous load case evaluations. Most wood I-joist manu- facturers have developed computer programs, load and span tables, or both that take these various load cases into consideration.
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Figure M7.4-2 Load Case Evaluations
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Floor Performance
- quirements of a building code may not always provide acceptable performance to the end user. Although mini-
the imposed loads, the system ultimately must perform to the satisfaction of the end user. Since expectancy levels
system becomes a subjective issue requiring judgment as to the sensitivity of the intended occupant.
factor, there are other equally important variables that can
- mance than a nailed only system. Selection of the decking
the sheathing material between joists can be reduced by placing the joists at a closer on center spacing or increasing the sheathing thickness.
Proper installation and job site storage are important considerations. All building materials, including wood I-joists, need to be kept dry and protected from exposure to the elements. Proper installation includes correct spac- ing of sheathing joints, care in fastening of the joists and sheathing, and providing adequate and level supports. All of these considerations are essential for proper system performance.
systems that are stiff and where very little dead load (i.e., partition walls, ceilings, furniture, etc.) exists. Vibration can generally be damped with a ceiling system directly
-
to the end walls) can also help minimize the potential for vibration in the absence of a direct applied ceiling. Limit- ing the span/depth ratio of the I-joist may also improve
Joist Bearing
Bearing design for wood I-joists requires more than consideration of perpendicular to grain bearing values. Minimum required bearing lengths take into account a number of considerations. These include: cross grain
connection to the joist web, adhesive joint locations and strength, and perpendicular to grain bearing stresses. The model building code evaluation reports provide a source
for bearing design information, usually in the form of minimum required bearing lengths.
Usually, published bearing lengths are based on the maximum allowable shear capacity of the particular product and depth or allowable reactions are related to
are most often based on empirical test results rather than a
consulted for information when deviations from published criteria are desired.
To better understand the variables involved in a wood I-joist bearing, it’s convenient to visualize the member as
web resists the vertical shear forces. Using this concept, shear forces accumulate in the web member at the bearing
the support structure. This transfer involves two critical
bearing involves perpendicular to grain stresses. The low-
material is usually used to develop the minimum required bearing area.
The second interface to be checked is between the
-
a waterproof structural adhesive. The contact surfaces
In most cases, the adhesive line stresses at this joint control the bearing length design. The effective bearing
- mental length related to the thickness and stiffness of the
Since most wood I-joists have web shear capacity
reinforcement is sometimes utilized. The most common method of reinforcement is the addition of web stiffen- ers (also commonly referred to as bearing blocks). Web stiffeners are vertically oriented wood blocks positioned on both sides of the web. Web stiffeners should be cut so that a gap of at least 1/8" is between the stiffener and the
a span. Figure M7.4-3 provides an illustration of a typical end bearing assembly.
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Figure M7.4-3 End Bearing Web Stiffeners (Bearing Block)
Web Stiffeners
When correctly fastened to the joist web, web stiffen- ers transfer some of the load from the web into the top of
is usually mechanically connected to the web with nails or staples loaded in double shear. For some of the higher capacity wood I-joists, nailing and supplemental gluing with a structural adhesive is required. The added bearing capacity achievable with web stiffeners is limited by the allowable bearing stresses where the stiffeners contact
the web. Web stiffeners also serve the implied function of
reinforcing the web against buckling. Since shear capac- ity usually increases proportionately with the depth, web stiffeners are very important for deep wood I-joists. For example, a 30" deep wood I-joist may only develop 20% to 30% of its shear and bearing capacity without properly attached web stiffeners at the bearing locations. This is especially important at continuous span bearing locations, where reaction magnitudes can exceed simple span reac- tions by an additional 25%.
Web stiffeners should be cut so that a gap of at least 1/8" is between the stiffener and the top or bottom of the
For shallow depth joists, where relatively low shear capacities are required, web stiffeners may not be needed. When larger reaction capacities are required, web stiffener reinforcement may be needed, especially where short bearing lengths are desired. Figure M7.4-4 illustrates the bearing interfaces.
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46 M7: PREFABRICATED WOOD I-JOISTS
Figure M7.4-4 Web Stiffener Bearing Interface
Figure M7.4-5 Beveled End CutBeveled End Cuts
Beveled end cuts, where the end of the joist is cut on
- sideration. Again the severity of the angle, web material, location of web section joints, and web stiffener applica- tion criteria effect the performance of this type of bearing
be consulted for limits on this type of end cut. It is generally accepted that if a wood I-joist has the
the joist is not cut beyond the face of bearing (measured
there is no reduction in shear or reaction capacity. This differs from the conventional lumber provision that sug- gests there is no decrease in shear strength for beveled cuts of up to an angle of 45o. The reason involves the composite nature of the wood I-joist and how the mem- ber fails in shear and or bearing. Figure M7.4-5 provides an illustration of the beveled end cut limitation.
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Sloped Bearing Conditions
Sloped bearing conditions require design consider- ations different from conventional lumber. An example is
Figure M7.4-6). This type of bearing should only be used on the low end bearing for wood I-joists. Another example is the use of metal joist support connectors that attach only to the web area of the joist and do not provide a bottom seat in which to bear. In general, this type of connector is not recommended for use with wood I-joists without consideration for the resulting reduced capacity.
The birdsmouth cut is a good solution for the low end bearing when the slope is steep and the tangential loads are high (loads along the axis of the joist member). This assumes the quality of construction is good and the cuts are made correctly and at the right locations. This type of
bearing cut requires some skill and is not easy to make, -
pacity, especially with high shear capacity members, may
bearing area is reduced. The notched cut will also reduce the member’s shear and moment capacity at a cantilever location.
An alternative to a birdsmouth cut is a beveled bear- ing plate matching the joist slope or special sloped seat bearing hardware manufactured by some metal connector suppliers. These alternatives also have special design con- siderations with steep slope applications. As the member slope increases, so does the tangential component of
- ing nailing or straps to provide resistance. Figure M7.4-6 shows some examples of acceptable low end bearing conditions.
Figure M7.4-6 Sloped Bearing Conditions (Low End)
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48 M7: PREFABRICATED WOOD I-JOISTS
suitable connector or on a beveled plate is recommended.
to resist the tangential component of the reaction. Support connections only to the web area of a wood
I-joist, especially at the high end of a sloped application, are not generally recommended. Since a wood I-joist is comprised of a number of pieces, joints between web sec- tions occurring near the end of the member may reduce the joist’s shear capacity when not supported from the
When a wood I-joist is supported from the web only, the closest web to web joint from the end may be stressed in tension. This could result in a joint failure with the
these internal joints away from the end of the member or applying joint reinforcements are potential remedies, but
The best bearing solution is to provide direct sup-
capacity. Figure M7.4-7 shows typical high end bearing conditions.
Figure M7.4-7 Sloped Bearing Conditions (High End)
Connector Design/Joist Hangers
Although there are numerous hangers and connectors available that are compatible with wood I-joists, many are not. Hangers developed for conventional lumber or glulam beams often use large nails and space them in a pattern
selection considerations for wood I-joists should include nail length and diameter, nail location, wood I-joist bearing capacity, composition of the supporting member, physical
for a wood I-joist to glulam beam support may not be compatible for an I-joist to I-joist connection.
the diameter of a 10d common nail, with a recommended length no greater than 1½". Nails into web stiffeners should
not exceed the diameter of a 16d common nail. Nails through the sides of the hanger, when used in combina- tion with web stiffeners, can be used to reduce the joist’s minimum required bearing length. Nails help transfer loads directly from the I-joist web into the hanger, reducing the load transferred through direct bearing in the bottom hanger seat.
Hangers should be capable of providing lateral support
As a minimum, hanger support should extend to at least mid-height of a joist used with web stiffeners. Some con-
for use with wood I-joists that provide full lateral support without the use of web stiffeners. Figure M7.4-8 illustrates lateral joist support requirements for hangers.
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Figure M7.4-8 Lateral Support Requirements for Joists in Hangers
web stiffeners need to be installed tight to the bottom
M7.4-9). When face-nail hangers are used for joist to joist
connections, nails into the support joist should extend through and beyond the web element (Figure M7.4-10).
Figure M7.4-9 Top Flange Hanger Support
support for the hanger. Again, nail diameter should be
Multiple I-joists need to be adequately connected together to achieve desired performance. This requires proper selection of a nailing or bolting pattern and atten- tion to web stiffener and blocking needs. Connections should be made through the webs of the I-joists and never
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50 M7: PREFABRICATED WOOD I-JOISTS
For a double I-joist member loaded from one side only, the minimum connection between members should be capable of transferring at least 50% of the applied load. Likewise, for a triple member loaded from one side only, the minimum connection between members must be capable of transferring at least 2/3 of the applied load. The actual connection design should consider the potential slip and differential member stiffness. Many manufactur- ers recommend limiting multiple members to three joists.
limited to two members.
The low torsional resistance of most wood I-joists is also a design consideration for joist to joist connections.
hanger hung from the side of a double joist, create the
straps, blocking, or directly applied ceiling systems may be needed on heavily loaded eccentric connections to resist rotation. Figure M7.4-10 shows additional I-joist connec- tion considerations for use with face nail hangers.
Figure M7.4-10 Connection Requirements for Face Nail Hangers
Vertical Load Transfer
Bearing loads originating above the joists at the bear- ing location require blocking to transfer these loads around the wood I-joist to the supporting wall or foundation. This is typically the case in a multi-story structure where bear- ing walls stack and platform framing is used. Usually, the available bearing capacity of the joist is needed to support its reaction, leaving little if any excess capacity to support additional bearing wall loads from above.
The most common type of blocking uses short pieces of wood I-joist, often referred to as blocking panels,
in between the joists. These panels also provide lateral support for the joists and an easy means to transfer lateral diaphragm shears.
The ability to transfer lateral loads (due to wind, seis- mic, construction loads, etc.) to shear walls or foundations below is important to the integrity of the building design. Compared with dimension lumber blocking, which usually is toe-nailed to the bearing below, wood I-joist blocking can develop higher diaphragm transfer values because of a wider member width and better nail values.
are pre-cut in strips equal to the joist depth and provide support for the loads from above. This solution may also provide diaphragm boundary nailing for lateral loads.
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A third method uses vertically oriented short studs, often called squash blocks or cripple blocks, on each side of the joist and cut to a length slightly longer than the depth of the joist. This method should be used in combination with some type of rim joist or blocking material when lateral stability or diaphragm transfer is required.
The use of horizontally oriented sawn lumber as a blocking material is unacceptable. Wood I-joists generally do not shrink in the vertical direction due to their panel
Figure M7.4-11 Details for Vertical Load Transfer
Web Holes
Holes cut in the web area of a wood I-joist affect the member’s shear capacity. Usually, the larger the hole, the greater the reduction in shear capacity. For this reason, holes are generally located in areas where shear stresses are low. This explains why the largest holes are gener- ally permitted near mid-span of a member. The required spacing between holes and from the end of the member is
during manufacturing. The allowable shear capacity of a wood I-joist at
These include: percentage of web removed, proximity to a vertical joint between web segments, the strength of the
the shear strength of the web material. Since wood I-joists
are manufactured using different processes and materials, each manufacturer should be consulted for the proper web hole design.
The methodology used to analyze application loads is important in the evaluation of web holes. All load cases that will develop the highest shear at the hole location should be considered. Usually, for members resisting simple uniform design loads, the loading condition that develops the highest shear loads in the center area of a joist span involves partial span loading.
Web holes contribute somewhat to increased de-
Provided not too many holes are involved, the contribution is negligible. In most cases, if the manufacturer’s hole criteria are followed and the number of holes is limited to
warrant consideration.
type web, creating the potential for a mismatch in height as sawn lumber shrinks to achieve equilibrium. When conventional lumber is used in the vertical orientation, shrinkage problems are not a problem because changes in elongation due to moisture changes are minimal. Figure M7.4-11 shows a few common methods for developing vertical load transfer.
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53ASD/LRFD MANUAL FOR ENGINEERED WOOD CONSTRUCTION
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M8: STRUCTURAL COMPOSITE LUMBER
M8.1 General 54
M8.2 Reference Design Values 55
M8.3 Adjustment of Reference Design Values 56
M8.4 Special Design Considerations 57 8
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54 M8: STRUCTURAL COMPOSITE LUMBER
M8.1 General
Common Uses
SCL is widely used as a framing material for housing. SCL is made in different grades and with various processes and can be utilized in numerous applications. Proper de- sign is required to optimize performance and economics.
use in commercial and industrial construction. Its high strength, stiffness, universal availability, and cost saving attributes make it a viable alternative in most low-rise construction projects.
SCL is used as beams, headers, joists, rafters, studs, and plates in conventional construction. In addition, SCL is used to fabricate structural glued laminated beams, trusses, and prefabricated wood I-joists.
Availability
SCL is regarded as a premium construction material
individual projects, the customer should be aware of the species and strength availability. Sizes vary with each individual product. The best source of this information is your local lumber supplier, distribution center, or SCL manufacturer. Proper design is facilitated through the use of manufacturer’s literature, code reports, and software available from SCL manufacturers.
Product Information
Structural composite lumber (SCL) products are well known throughout the construction industry. The advan-
process control. SCL is manufactured from strips or full sheets of
veneer. The process typically includes alignment of stress
material together under heat and pressure. By redistrib- uting natural defects and through state of the art quality control procedures, the resulting material is extremely consistent and maximizes the strength and stiffness of
The material is typically produced in a long length
resawn into required dimensions for use. Material is cur- rently available in a variety of depths from 4-3/8" to 24" and thicknesses from 3/4" to 7".
SCL is available in a wide range of sizes and grades. When specifying SCL products, a customer may specify on the basis of size, stress (strength), or appearance.
SCL products are proprietary and are covered by code acceptance reports by one or all of the model build- ing codes. Such reports should be consulted for current design information while manufacturer’s literature can be consulted for design information, sizing tables, and installation recommendations.
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M8.2 Reference Design Values
General
As stated in NDS 8.2, SCL products are proprietary and each manufacturer develops design values appropri- ate for their products. These values are reviewed by the model building codes and published in acceptance reports and manufacturer’s literature.
Reference design values are used in conjunction with the adjustment factors in M8.3.
Shear Design
SCL is typically designed and installed as a rectangu- lar section. Loads near supports may be reduced per NDS 3.4.3.1. However, such load must be included in bearing calculations. Shear values for SCL products often change with member orientation.
Bearing
SCL typically has high Fc and Fc properties. With the higher shear and bending capacities, shorter or con- tinuous spans are often controlled by bearing. The user is cautioned to ensure the design accounts for compression of the support material (i.e., plate) as well as the beam material. Often the plate material is of softer species and will control the design.
Bending
Published bending capacities of SCL beams are deter- mined from testing of production specimens. Adjustment for the size of the member is also determined by test.
Field notching or drilling of holes is typically not al- lowed. Similarly, excessive nailing or the use of improper nail sizes can cause splitting that will also reduce capacity. The manufacturer should be contacted when evaluating a damaged beam.
Deflection Design
provisions for other rectangular wood products (see M3.5).
individual manufacturer’s product literature or evaluation reports. Some manufacturers might publish “true” E values which would require additional calculations to account for
NDS Appendix F).
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56 M8: STRUCTURAL COMPOSITE LUMBER
M8.3 Adjustment of Reference Design Values Member design capacity is the product of reference
design values, adjustment factors, and section properties. Reference design values for SCL are discussed in M8.2.
Adjustment factors are provided for applications outside the reference end-use conditions and for member
NDS 8.3. When one
conditions are beyond the range of the reference condi- tions, these adjustment factors shall be used to modify the appropriate property. Adjustment factors for the effects of
provided in NDS 8.3. Additional adjustment factors can be found in the manufacturer’s product literature or code evaluation report. Table M8.3-1 shows the applicability of adjustment factors for SCL in a slightly different format for the designer.
Certain products may not be suitable for use in some applications or with certain treatments. Such conditions
- facturer warranties. The manufacturer or code evaluation
Bending Member Example For fully laterally supported members stressed in
strong axis bending and used in a normal building envi- ronment (meeting the reference conditions of NDS 2.3 and 8.3), the adjusted design values reduce to:
For ASD: Fb = Fb CD CV
Fv = Fv CD
Fc = Fc Cb
E = E
For LRFD: Fb = Fb CV KF b
Fv = Fv KF v
Fc = Fc Cb KF c
E = E
Axially Loaded Member Example For axially loaded members used in a normal building
environment (meeting the reference conditions of NDS 2.3 and 8.3) designed to resist tension or compression loads, the adjusted tension or compression design values reduce to:
For ASD: Fc = Fc CD CP
Ft = Ft CD
Emin = Emin
For LRFD: Fc = Fc CP KF c
Ft = Ft KF t
Emin = Emin KF s
Table M8.3-1 Applicability of Adjustment Factors for Structural Composite Lumber1
Allowable Stress Design Load and Resistance Factor Design Fb b CD CM Ct CL CV Cr Fb b CM Ct CL CV Cr KF b Ft t CD CM Ct Ft t CM Ct KF t Fv v CD CM Ct Fv v CM Ct KF v Fc c CM Ct Cb Fc c CM Ct Cb KF c Fc c CD CM Ct CP Fc c CM Ct CP KF c
M Ct M Ct Emin min CM Ct Emin min CM Ct KF s 1. See NDS 8.3.6 for information on simultaneous application of the volume factor, CV, and the beam stability factor, CL.
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M8.4 Special Design Considerations
General
With proper detailing and protection, SCL can perform well in a variety of environments. One key to proper de- tailing is planning for the natural shrinkage and swelling of wood members as they are subjected to various drying and wetting cycles. While moisture changes have the larg- est impact on lumber dimensions, some designs must also check the effects of temperature. While SCL is typically produced using dry veneer, some moisture accumulation
-
from using such product as it will “shrink” as it dries. In addition to designing to accommodate dimensional
performance, which is covered in Chapter M16.
Dimensional Changes
The dimensional stability and response to temperature effects of engineered lumber is similar to that of solid sawn lumber of the same species.
volume and can therefore hold more water than a solid sawn equivalent. When soaked these products expand and dimensional changes can occur.
Adhesive applied during certain processes tends to form a barrier to moisture penetration. Therefore, the material will typically take longer to reach equilibrium than its solid sawn counterpart.
For given temperatures and applications, different levels of relative humidity are present. This will cause the material to move toward an equilibrium moisture content (EMC). Eventually all wood products will reach their EMC for a given environment. SCL will typically equilibrate at a lower EMC (typically 3% to 4% lower) than solid sawn lumber and will take longer to reach an ambient EMC. Normal swings in humidity during the service life of the structure should not produce noticeable dimensional changes in SCL members.
More information on designing for moisture and tem- perature change is included in M4.4.
Durability
Designing for durability is a key part of the archi- tectural and engineering design of the building. Wood exposed to high levels of moisture can decay over time. While there are exceptions – such as naturally durable spe- cies, preservative-treated wood, and those locations that can completely air-dry between moisture cycles – prudent design calls for a continuing awareness of the possibility of moisture accumulation. Awareness of the potential for de- cay is the key – many design conditions can be detailed to minimize the accumulation of moisture; for other problem conditions, preservative-treated wood or naturally durable
This section cannot cover the topic of designing for durability in detail. There are many excellent texts that de- vote entire chapters to the topic, and designers are advised
design areas, such as:
structures in high moisture or humid condi- tions where wood comes in contact with concrete or masonry where wood members are supported in steel hangers or connectors in which condensation could collect anywhere that wood is directly or indirectly exposed to the elements where wood, if it should ever become wet, could not naturally dry out.
This list is not intended to be all-inclusive – it is merely an attempt to alert designers to special conditions that may cause problems when durability is not considered in the design.
More information on detailing for durability is in- cluded in M4.4.
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M9: WOOD STRUCTURAL PANELS
M9.1 General 60
M9.2 Reference Design Values 60
M9.3 Adjustment of Reference Design Values 66
M9.4 Special Design Considerations 67 9
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60 M9: WOOD STRUCTURAL PANELS
M9.1 General Product Description
Wood structural panels are wood-based panel products that have been rated for use in structural applications. Com- mon applications for wood structural panels include roof
is also manufactured in various sanded grades.
Panel span ratings identify the maximum recommended
are provided on the basis of span ratings. Sanded grades are classed according to nominal thick-
ness and design capacities are provided on that basis.
Designers must specify wood structural panels by the span ratings, nominal thicknesses, grades, and construc- tions associated with tabulated design recommendations.
-
Single Floor panels may have tongue-and-groove or square edges. If square edge Single Floor panels are
between supports. Table M9.1-1 provides descriptions and typical uses
for various panel grades and types.
M9.2 Reference Design Values General
Wood structural panel design capacities listed in Tables M9.2-1 through M9.2-2 are minimum for grade and span rating. Multipliers shown in each table provide adjust- ments in capacity for Structural I panel grades. To take
that the correct panel is used in construction. The tabulated capacities and adjustment factors are
based on data from tests of panels manufactured in ac- cordance with industry standards and which bear the
Structural panels have a strength axis direction and a cross panel direction. The direction of the strength axis
face strands or plywood face veneer grain and is the long dimension of the panel unless otherwise indicated by the manufacturer. This is illustrated in Figure M9.2-1.
Figure M9.2-1 Structural Panel with Strength Direction Across Supports
8-ft Typical
4-ft T ypic
al
StrengthDirection
Panel Stiffness and Strength
Panel design capacities listed in Table M9.2-1 are based
testing according to principles of ASTM D3043 Method C (large panel testing).
Stiffness (EI) -
tion and is represented as EI. E is the reference modulus of elasticity of the material, and I is the moment of inertia of the cross section. The units of EI are lb-in.2 per foot of panel width.
Strength (FbS) Bending strength capacity is the design maximum
moment, represented as FbS. Fb is the reference extreme
modulus of the cross section. The units of FbS are lb-in. per foot of panel width.
Figure M9.2-2 Example of Structural Panel in Bending
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Table M9.1-1 Guide to Panel Use
Panel Construction
Panel Grade Description & Use Common Nominal
Thickness (in.)
OSB COM-PLY Plywood & Veneer
Grade
Sheathing EXP 1
Unsanded sheathing grade for wall, roof,
such as pallets and for engineering design with proper capacities. Manufactured with intermediate and exterior glue. For long- term exposure to weather or moisture, only Exterior type plywood is suitable.
5/16, 3/8, 15/32, 1/2, 19/32, 5/8, 23/32, 3/4
Yes Yes Yes, face C, back D, inner D
Structural I Sheathing EXP 1
Panel grades to use where shear and cross- panel strength properties are of maximum importance. Made with exterior glue only. Plywood Structural I is made from all Group 1 woods.
19/32, 5/8, 23/32, 3/4
Yes Yes Yes, face C, back D, inner D
Single Floor EXP 1 Provides smooth surface for application
of carpet and pad. Possesses high concentrated and impact load resistance during construction and occupancy. Manufactured with intermediate (plywood) and exterior glue. Touch-sanded. Available with tongue-and-groove edges.
19/32, 5/8, 23/32, 3/4,
7/8, 1, 1-3/32, 1-1/8
Yes Yes Yes, face
C-Plugged, back D, inner D
Underlayment EXP 1 or INT
For underlayment under carpet and pad. Available with exterior glue. Touch- sanded. Available with tongue-and-groove edges.
1/4, 11/32, 3/8, 15/32, 1/2, 19/32, 5/8, 23/32,
3/4
No No Yes, face
C-Plugged, back D, inner D
C-D-Plugged EXP 1
For built-ins, wall and ceiling tile backing. Not for underlayment. Available with exterior glue. Touch-sanded.
1/2, 19/32, 5/8, 23/32,
3/4
No No Yes, face C-Plugged,
back D, inner D
Sanded Grades EXP 1 or INT
Generally applied where a high-quality surface is required. Includes APA N-N, N-A, N-B, N-D, A-A, A-D, B-B, and B-D INT grades.
1/4, 11/32, 3/8, 15/32, 1/2, 19/32, 5/8, 23/32,
3/4
No No Yes, face B or
better, back D or better, inner C & D
Marine EXT Superior Exterior-type plywood made only
solid-core construction. Available with medium density overlay (MDO) or high density overlay (HDO) face. Ideal for boat hull construction.
1/4, 11/32, 3/8, 15/32, 1/2, 19/32, 5/8, 23/32,
3/4
No No Yes, face A
or face B, back A
or inner B
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Axial Capacities
Axial Stiffness (EA) Panel axial stiffnesses listed in Table M9.2-2 are based
on testing according to the principles of ASTM D3501 Method B. Axial stiffness is the capacity to resist axial strain and is represented as EA. E is the reference axial modulus of elasticity of the material, and A is the area of the cross section. The units of EA are pounds per foot of panel width.
Table M9.2-1 Wood Structural Panel Bending Stiffness and Strength
Stress Parallel to Strength Axis1 Stress Perpendicular to Strength Axis1
Span Rating
Plywood Plywood 3-ply 4-ply 5-ply OSB 3-ply 4-ply 5-ply OSB
PANEL BENDING STIFFNESS, EI (lb-in.2/ft of panel width) 24/0 66,000 66,000 66,000 60,000 3,600 7,900 11,000 11,000
24/16 86,000 86,000 86,000 78,000 5,200 11,500 16,000 16,000
32/16 125,000 125,000 125,000 115,000 8,100 18,000 25,000 25,000
40/20 250,000 250,000 250,000 225,000 18,000 39,500 56,000 56,000
48/24 440,000 440,000 440,000 400,000 29,500 65,000 91,500 91,500
16oc 165,000 165,000 165,000 150,000 11,000 24,000 34,000 34,000
20oc 230,000 230,000 230,000 210,000 13,000 28,500 40,500 40,500
24oc 330,000 330,000 330,000 300,000 26,000 57,000 80,500 80,500
32oc 715,000 715,000 715,000 650,000 75,000 165,000 235,000 235,000
48oc 1,265,000 1,265,000 1,265,000 1,150,000 160,000 350,000 495,000 495,000
Multiplier for
Structural I Panels 1.0 1.0 1.0 1.0 1.5 1.5 1.6 1.6
PANEL BENDING STRENGTH, FbS (lb-in./ft of panel width) 24/0 250 275 300 300 54 65 97 97
24/16 320 350 385 385 64 77 115 115
32/16 370 405 445 445 92 110 165 165
40/20 625 690 750 750 150 180 270 270
48/24 845 930 1,000 1,000 225 270 405 405
16oc 415 455 500 500 100 120 180 180
20oc 480 530 575 575 140 170 250 250
24oc 640 705 770 770 215 260 385 385
32oc 870 955 1,050 1,050 380 455 685 685
48oc 1,600 1,750 1,900 1,900 680 815 1,200 1,200
Multiplier for
Structural I Panels 1.0 1.0 1.0 1.0 1.3 1.4 1.5 1.5
1. Strength axis is defined as the axis parallel to the face and back orientation of the flakes or the grain (veneer), which is generally the long panel direction, unless otherwise marked.
Tension (FtA) Tension capacities listed in Table M9.2-2 are based
on testing according to the principles of ASTM D3500 Method B. Tension capacity is given as FtA. Ft is the reference tensile stress of the material, and A is the area of the cross section. The units of FtA are pounds per foot of panel width.
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Table M9.2-2 Wood Structural Panel Axial Stiffness, Tension, and Compression Capacities
Span Rating
Stress Parallel to Strength Axis1 Stress Perpendicular to Strength Axis1
Plywood Plywood 3-ply 4-ply 5-ply OSB 3-ply 4-ply 5-ply OSB
PANEL TENSION, FtA (lb/ft of panel width) 24/0 2,300 2,300 3,000 2,300 600 600 780 780
24/16 2,600 2,600 3,400 2,600 990 990 1,300 1,300
32/16 2,800 2,800 3,650 2,800 1,250 1,250 1,650 1,650
40/20 2,900 2,900 3,750 2,900 1,600 1,600 2,100 2,100
48/24 4,000 4,000 5,200 4,000 1,950 1,950 2,550 2,550
16oc 2,600 2,600 3,400 2,600 1,450 1,450 1,900 1,900
20oc 2,900 2,900 3,750 2,900 1,600 1,600 2,100 2,100
24oc 3,350 3,350 4,350 3,350 1,950 1,950 2,550 2,550
32oc 4,000 4,000 5,200 4,000 2,500 2,500 3,250 3,250
48oc 5,600 5,600 7,300 5,600 3,650 3,650 4,750 4,750
Multiplier for
Structural I Panels 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0
PANEL COMPRESSION, FcA (lb/ft of panel width) 24/0 2,850 4,300 4,300 2,850 2,500 3,750 3,750 2,500
24/16 3,250 4,900 4,900 3,250 2,500 3,750 3,750 2,500
32/16 3,550 5,350 5,350 3,550 3,100 4,650 4,650 3,100
40/20 4,200 6,300 6,300 4,200 4,000 6,000 6,000 4,000
48/24 5,000 7,500 7,500 5,000 4,800 7,200 7,200 4,300
16oc 4,000 6,000 6,000 4,000 3,600 5,400 5,400 3,600
20oc 4,200 6,300 6,300 4,200 4,000 6,000 6,000 4,000
24oc 5,000 7,500 7,500 5,000 4,800 7,200 7,200 4,300
32oc 6,300 9,450 9,450 6,300 6,200 9,300 9,300 6,200
48oc 8,100 12,150 12,150 8,100 6,750 10,800 10,800 6,750
Multiplier for
Structural I Panels 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0
PANEL AXIAL STIFFNESS, EA (lb/ft of panel width) 24/0 3,350,000 3,350,000 3,350,000 3,350,000 2,900,000 2,900,000 2,900,000 2,900,000
24/16 3,800,000 3,800,000 3,800,000 3,800,000 2,900,000 2,900,000 2,900,000 2,900,000
32/16 4,150,000 4,150,000 4,150,000 4,150,000 3,600,000 3,600,000 3,600,000 3,600,000
40/20 5,000,000 5,000,000 5,000,000 5,000,000 4,500,000 4,500,000 4,500,000 4,500,000
48/24 5,850,000 5,850,000 5,850,000 5,850,000 5,000,000 5,000,000 5,000,000 4,500,000
16oc 4,500,000 4,500,000 4,500,000 4,500,000 4,200,000 4,200,000 4,200,000 4,200,000
20oc 5,000,000 5,000,000 5,000,000 5,000,000 4,500,000 4,500,000 4,500,000 4,500,000
24oc 5,850,000 5,850,000 5,850,000 5,850,000 5,000,000 5,000,000 5,000,000 4,500,000
32oc 7,500,000 7,500,000 7,500,000 7,500,000 7,300,000 7,300,000 7,300,000 5,850,000
48oc 8,200,000 8,200,000 8,200,000 8,200,000 7,300,000 7,300,000 7,300,000 7,300,000
Multiplier for
Structural I Panels 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0
1. Strength axis is defined as the axis parallel to the face and back orientation of the flakes or the grain (veneer), which is generally the long panel direction, unless otherwise marked.
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Figure M9.2-5 Through-the-Thickness Shear for Wood Structural Panels
Figure M9.2-3 Structural Panel with Axial Compression Load in the Plane of the Panel
Compression (FcA) Compression (Figure M9.2-3) capacities listed in
Table M9.2-2 are based on testing according to the prin- ciples of ASTM D3501 Method B. Compressive properties
was eliminated by restraining the edges of the specimens during testing. Compression capacity is given as FcA. Fc is the reference compression stress of the material, and A is the area of the cross section. The units of FcA are pounds per foot of panel width.
Shear Capacities
Planar (Rolling) Shear (Fs[Ib/Q]) Shear-in-the-plane of the panel (rolling shear) capaci-
ties listed in Table M9.2-3 are based on testing according to the principles of ASTM D2718. Shear strength in the plane of the panel is the capacity to resist horizontal shear breaking loads when loads are applied or developed on op-
bending. Planar shear capacity is given as Fs[Ib/Q]. Fs is the reference material stress, and Ib/Q is the panel cross- sectional shear constant. The units of Fs[Ib/Q] are pounds per foot of panel width.
Rigidity Through-the-Thickness (Gvtv) Panel rigidities listed in Table M9.2-4 are based on
testing according to the principles of ASTM D2719 Meth- od C. Panel rigidity is the capacity to resist deformation under shear through the thickness stress (Figure M9.2-5). Rigidity is given as Gvtv. Gv is the reference modulus of rigidity, and tv is the effective panel thickness for shear. The units of Gvtv are pounds per inch of panel depth (for vertical applications). Multiplication of Gvtv by panel depth gives GA, used by designers for some applications.
Through-the-Thickness Shear (Fvtv) Through-the-thickness shear capacities listed in Table
M9.2-4 are based on testing according to the principles of ASTM D2719 Method C. Allowable through the thickness shear is the capacity to resist horizontal shear breaking loads when loads are applied or developed on opposite edges of the panel (Figure M9.2-5), such as in an I-beam. Where additional support is not provided to prevent bucking, design capacities in Table M9.2-4 are limited to sections 2 ft or less in depth. Deeper sections may require additional reductions. Fv is the reference stress of the material, and tv is the effective panel thickness for shear. The units of Fvtv are pounds per inch of shear resisting panel length.
Figure M9.2-4 Planar (Rolling) Shear or Shear-in-the-Plane for Wood Structural Panels
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Table M9.2-3 Wood Structural Panel Planar (Rolling) Shear Capacities
Table M9.2-4 Wood Structural Panel Rigidity and Through-the-Thickness Shear Capacities
Stress Parallel to Strength Axis Stress Perpendicular to Strength Axis
Span Plywood Plywood Rating 3-ply 4-ply 5-ply OSB 3-ply 4-ply 5-ply OSB
PANEL SHEAR-IN-THE-PLANE, Fs(Ib/Q) (lb/ft of panel width)
24/0 155 155 170 130 275 375 130 130
24/16 180 180 195 150 315 435 150 150
32/16 200 200 215 165 345 480 165 165
40/20 245 245 265 205 430 595 205 205
48/24 300 300 325 250 525 725 250 250
16oc 245 245 265 205 430 595 205 205
20oc 245 245 265 205 430 595 205 205
24oc 300 300 325 250 525 725 250 250
32oc 360 360 390 300 630 870 300 300
48oc 460 460 500 385 810 1,100 385 385
Multiplier for
Structural I Panels 1.4 1.4 1.4 1.0 1.4 1.4 1.0 1.0
Span Rating
Stress Parallel to Strength Axis Stress Perpendicular to Strength Axis Plywood
OSB Plywood
OSB3-ply 4-ply 5-ply1 3-ply 4-ply 5-ply1
PANEL RIGIDITY THROUGH-THE-THICKNESS, Gvtv (lb/in. of panel depth) 24/0 25,000 32,500 37,500 77,500 25,000 32,500 37,500 77,500
24/16 27,000 35,000 40,500 83,500 27,000 35,000 40,500 83,500
32/16 27,000 35,000 40,500 83,500 27,000 35,000 40,500 83,500
40/20 28,500 37,000 43,000 88,500 28,500 37,000 43,000 88,500
48/24 31,000 40,500 46,500 96,000 31,000 40,500 46,500 96,000
16oc 27,000 35,000 40,500 83,500 27,000 35,000 40,500 83,500
20oc 28,000 36,500 42,000 87,000 28,000 36,500 42,000 87,000
24oc 30,000 39,000 45,000 93,000 30,000 39,000 45,000 93,000
32oc 36,000 47,000 54,000 110,000 36,000 47,000 54,000 110,000
48oc 50,500 65,500 76,000 155,000 50,500 65,500 76,000 155,000
Multiplier for
Structural I Panels 1.3 1.3 1.1 1.0 1.3 1.3 1.1 1.0
PANEL THROUGH-THE-THICKNESS SHEAR, Fvtv (lb/in. of shear-resisting panel length) 24/0 53 69 80 155 53 69 80 155
24/16 57 74 86 165 57 74 86 165
32/16 62 81 93 180 62 81 93 180
40/20 68 88 100 195 68 88 100 195
48/24 75 98 115 220 75 98 115 220
16oc 58 75 87 170 58 75 87 170
20oc 67 87 100 195 67 87 100 195
24oc 74 96 110 215 74 96 110 215
32oc 80 105 120 230 80 105 120 230
48oc 105 135 160 305 105 135 160 305
Multiplier for
Structural I Panels 1.3 1.3 1.1 1.0 1.3 1.3 1.1 1.0
t values for 4-ply panels.
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M9.3 Adjustment of Reference Design Values General
Adjusted panel design capacities are determined by multiplying reference capacities, as given in Tables M9.2- 1 through M9.2-4, by the adjustment factors in NDS 9.3. Some adjustment factors should be obtained from the manufacturer or other approved source. In the NDS Com- mentary, C9.3 provides additional information on typical adjustment factors.
Tabulated capacities provided in this Chapter are suitable for reference end-use conditions. Reference end-use conditions are consistent with conditions typi- cally associated with light-frame construction. For wood
Bending Member Example For non-Structural I grade wood structural panels,
greater than 24" in width, loaded in bending, and used in a normal building environment (meeting the reference conditions of NDS 2.3 and 9.3), the adjusted design values reduce to:
For ASD: Fb S = FbS CD
EI = EI For LRFD: FbS = FbS KF b
EI = EI
Axially Loaded Member Example For non-Structural I grade wood structural panels,
greater than 24" in width, axially loaded, and used in a normal building environment (meeting the reference con- ditions of NDS 2.3 and 4.3) designed to resist tension or compression loads, the adjusted tension or compression design values reduce to:
For ASD: Fc A = Fc A CD
Ft A = Ft A CD
EA = EA For LRFD: Fc A = Fc A KF c
Ft A = Ft A KF t
EA = EA
structural panels, these typical conditions involve the use of full-sized untreated panels in moderate temperature and moisture exposures.
Appropriate adjustment factors are provided for ap- plications in which the conditions of use are inconsistent with reference conditions. In addition to temperature and moisture, this includes consideration of panel treatment and size effects.
NDS Table 9.3.1 lists applicability of adjustment fac- tors for wood structural panels. Table M9.3-1 shows the applicability of adjustment factors for wood structural panels in a slightly different format for the designer.
Table M9.3-1 Applicability of Adjustment Factors for Wood Structural Panels
Allowable Stress Design Load and Resistance Factor Design Fb bS CD CM Ct CG Cs Fb bS CM Ct CG Cs KF b Ft tA CD CM Ct CG Cs Ft tA CM Ct CG Cs KF t Fvtv vtv CD CM Ct CG Fvtv vtv CM Ct CG KF v Fs s(Ib/Q) CD CM Ct CG Fs s(Ib/Q) CM Ct CG KF v Fc cA CD CM Ct CG Fc cA CM Ct CG KF c
M Ct CG M Ct CG M Ct CG M Ct CG
Gvtv vtv CM Ct CG Gvtv vtv CM Ct CG Fc c CM Ct CG Fc c CM Ct CG KF c
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M9.4 Special Design Considerations
Table M9.4-1 Panel Edge Support
Panel Edge Support
For certain span ratings, the maximum recommended roof span for sheathing panels is dependent upon panel edge support. Although edge support may be provided by lumber blocking, panel clips are typically used when edge support is required. Table M9.4-1 summarizes the relationship between panel edge support and maximum recommended spans.
Maximum Recommended Span (in.) Sheathing Span Rating
With Edge Support
Without Edge Support
24/0 24 201
24/16 24 24 32/16 32 28 40/20 40 32 48/24 48 36 1. 20 in. for 3/8-in. and 7/16-in. panels, 24 in. for 15/32-in. and 1/2-in.
panels.
Long-Term Loading
Wood-based panels under constant load will creep -
tion applications, panels are not normally under constant load and, accordingly, creep need not be considered in design. When panels will sustain permanent loads which will stress the product to one-half or more of its design capacity, allowance should be made for creep. Appropriate adjustments should be obtained from the manufacturer or an approved source.
Preservative Treatment
Capacities given in Tables M9.2-1 through M9.2-4 ap- ply without adjustment to plywood pressure-impregnated with preservatives and redried in accordance with Ameri-
of applicable treating industry standards, OSB and COM- PLY panels are not currently recommended for applications requiring pressure-preservative treating.
Fire Retardant Treatment
The information provided in this Chapter does not
in accordance with the recommendations of the company providing the treating and redrying service.
Panel Spacing
Wood-based panel products expand and contract slightly as a natural response to changes in panel moisture content. To provide for in-plane dimensional changes, panels should be installed with a 1/8" spacing at all panel end and edge joints. A standard 10d box nail may be used to check panel edge and panel end spacing.
Minimum Nailing
Minimum nailing for wood structural panel applica- tions is shown in Table M9.4-2.
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Table M9.4-2 Minimum Nailing for Wood Structural Panel Applications
Nail Spacing (in.) Recommended
Nail Size & Type Panel Intermediate
Application Edges Supports Single Floor–Glue-nailed installation5 Ring- or screw-shank 16, 20, 24 oc, 3/4-in. thick or less 6d1 12 12 24 oc, 7/8-in. or 1-in. thick 8d1 6 12 32, 48 oc, 32-in. span (c-c) 8d1 6 12 48 oc, 48-in. span (c-c) 8d2 6 6 Single Floor–Nailed-only installation5 Ring- or screw-shank 16, 20, 24 oc, 3/4-in. thick or less 6d 6 12 24 oc, 7/8-in. or 1-in. thick 8d 6 12 32, 48 oc, 32-in. span 8d2 6 12 48 oc, 48-in. span 8d2 6 6
3 Common smooth, ring- or screw-shank 7/16-in. to 1/2-in. thick 6d 6 12 7/8-in. thick or less 8d 6 12 Thicker panels 10d 6 6 Sheathing–Wall sheathing Common smooth, ring- or screw-shank or galvanized box3
1/2-in. thick or less 6d 6 12 Over 1/2-in. thick 8d 6 12 Sheathing–Roof sheathing Common smooth, ring- or screw-shank3
5/16-in. to 1-in. thick 8d 6 124
Thicker panels 8d ring- or screw-shank 6 124
or 10d common smooth 1. 8d common nails may be substituted if ring- or screw-shank nails are not available. 2. 10d ring-shank, screw-shank, or common nails may be substituted if supports are well seasoned. 3. Other code-approved fasteners may be used. 4. For spans 48 in. or greater, space nails 6 in. at all supports. 5. Where required by the authority having jurisdiction, increased nailing schedules may be required.
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M10: MECHANICAL CONNECTIONS
M10.1 General 70
M10.2 Reference Design Values 71
M10.3 Design Adjustment Factors 71
M10.4 Typical Connection Details 72
M10.5 Pre-Engineered Metal Connectors 80
10
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70 M10: MECHANICAL CONNECTIONS
M10.1 General Other Connectors
Just as the number of possible building geometries is limitless, so too is the number of possible connection geometries. In addition to providing custom fabrication of connectors to meet virtually any geometry that can be designed, metal connector manufacturers have several
above, including:
• framing anchors • holddown devices • straps and ties
These connectors are also generally proprietary con- nectors. See the manufacturer’s literature or M10.4 for more information regarding design.
Connections are designed so that no applicable ca- pacity is exceeded under loads. Strength criteria include lateral or withdrawal capacity of the connection, and tension or shear in the metal components. Some types of connections also include compression perpendicular to grain as a design criteria.
Users should note that design of connections may also be controlled by serviceability limitations. These limita-
product chapters.
Stresses in Members at Connections
Local stresses in connections using multiple fasteners can be evaluated in accordance with NDS Appendix E.
This Chapter covers design of connections between wood members using metal fasteners. Several common connection types are outlined below.
Dowel-Type (Nails, Bolts, Screws, Pins)
These connectors rely on metal-to-wood bearing for transfer of lateral loads and on friction or mechanical interfaces for transfer of axial (withdrawal) loads. They are commonly available in a wide range of diameters and lengths. More information is provided in Chapter M11.
Split Rings and Shear Plates
These connectors rely on their geometry to provide larger metal-to-wood bearing areas per connector. Both are installed into precut grooves or daps in the members. More information is provided in Chapter M12.
Timber Rivets
Timber rivets are a dowel-type connection, however, because the ultimate load capacity of such connections are limited by rivet bending and localized crushing of wood at the rivets or by the tension or shear strength of the
procedure is required. Timber rivet design loads are based on the lower of the maximum rivet bending load and the maximum load based on wood strength. Chapter M13 contains more information on timber rivet design.
Structural Framing Connections
Structural framing connections provide a single-piece connection between two framing members. They gener- ally consist of bent or welded steel, carrying load from the supported member (through direct bearing) into the
shear, or a combination of the two). Structural framing connections are proprietary connectors and are discussed in more detail in M10.4.
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M10.2 Reference Design Values Reference design values for mechanical connections
are provided in various sources. The NDS contains refer- ence design values for dowel-type connections such as nails, bolts, lag screws, wood screws, split rings, shear plates, drift bolts, drift pins, and timber rivets.
Pre-engineered metal connectors are proprietary and reference design values are provided in code evaluation reports. More information on their use is provided in M10.5.
M10.3 Design Adjustment Factors To generate connection design capacities, reference
design values for connections are multiplied by adjust- ment factors per NDS 10.3. Applicable adjustment factors
NDS Table 10.3.1. Table M10.3-1 shows the applicability of adjustment factors for connections in a slightly different format for the de- signer.
The following connection product chapters contain examples of the application of adjustment factors to refer- ence design values:
Chapter M11 – dowel-type fasteners, Chapter M12 – split ring and shear plate connectors, Chapter M13 – timber rivets.
Metal connector plates are proprietary connectors for trusses, and reference design values are provided in code evaluation reports.
Staples and many pneumatic fasteners are proprietary, and reference design values are provided in code evalu- ation reports.
Table M10.3-1 Applicability of Adjustment Factors for Mechanical Connections1
Allowable Stress Design Load and Resistance Factor Design Lateral Loads
Dowel-Type Fasteners D CM Ct Cg C Ceg Cdi Ctn M Ct Cg C Ceg Cdi Ctn KF z
Split Ring and Shear Plate Connectors
D CM Ct Cg C Cd Cst M Ct Cg C Cd Cst KF z D CM Ct Cg C Cd M Ct Cg C Cd KF z
Timber Rivets D CM Ct Cst M Ct Cst KF z
D CM Ct C Cst M Ct C Cst KF z Metal Plate Connectors D CM Ct M Ct KF z Spike Grids D CM Ct C M Ct C KF z
Withdrawal Loads Nails, Spikes, Lag Screws, Wood Screws, and Drift Pins D CM Ct Ceg Ctn M Ct Ceg Ctn KF z
1. See NDS Table 10.3.1 footnotes for additional guidance on application of adjustment factors for mechanical connections.
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M10.4 Typical Connection Details 1. Beam on shelf in wall. The bearing plate distributes the load and keeps the beam from direct contact with the concrete. Steel angles provide uplift resistance and can also provide some lateral resistance. The end of the beam should not be in direct contact with the concrete.
2. Similar to detail 1 with a steel bearing plate only under the beam.
3. Similar to detail 1 with slotted holes to accommodate slight lateral movement of the beam under load. This detail is more commonly used when the beam is sloped, rather
General Concepts of Well- Designed Connections
Connections must obviously provide the structural strength necessary to transfer loads. Well-designed con- nections hold the wood members in such a manner that shrinkage/swelling cycles do not induce splitting across the grain. Well-designed connections also minimize re- gions that might collect moisture – providing adequate clearance for air movement to keep the wood dry. Finally, well-designed connections minimize the potential for ten- sion perpendicular to grain stresses – either under design conditions or under unusual loading conditions.
The following connection details (courtesy of the Ca- nadian Wood Council) are organized into nine groups:
1. Beam to concrete or masonry wall connections 2. Beam to column connections 3. Column to base connections 4. Beam to beam connections 5. Cantilever beam connections 6. Arch peak connections 7. Arch base to support 8. Moment splice 9. Problem connections
Many of the detail groups begin with a brief discus-
of connection. Focusing on the key design concepts of a broad class of connections often leads to insights regarding
Group 1. Beam to Concrete or Masonry Wall Connections
Design concepts. Concrete is porous and “wicks” moisture. Good detailing never permits wood to be in direct contact with concrete.
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Group 2. Beam to Column Connections Design concepts. All connections in the group must
hold the beam in place on top of the column. Shear transfer is reasonably easy to achieve. Some connections must also resist some beam uplift. Finally, for cases in which the beam is spliced, rather than continuous over the column, transfer of forces across the splice may be required.
4. Simple steel dowel for shear transfer.
5. Concealed connection in which a steel plate is inserted into a kerf in both the beam and the column. Transverse pins or bolts complete the connection.
6. Custom welded column caps can be designed to transfer shear, uplift, and splice forces. Note design variations to
differing plate widths to accommodate differences between the column and the beam widths.
7. Combinations of steel angles and straps, bolted and screwed, to transfer forces.
8. A very common connection – beam seat welded to the top of a steel column.
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74 M10: MECHANICAL CONNECTIONS
9. When both beams and columns are continuous and the connection must remain in-plane, either the beam or the column must be spliced at the connection. In this detail the column continuity is maintained. Optional shear plates may be used to transfer higher loads. Note that, unless the bolt heads are completely recessed into the back of the bracket, the beam end will likely require slotting. In a building with
the beam direction when using this connection.
Group 3. Column to Base Connections Design concepts. Since this is the bottom of the struc-
ture, it is conceivable that moisture from some source might run down the column. Experience has shown that base plate details in which a steel “shoe” is present can collect moisture that leads to decay in the column.
10. Similar to detail 4, with a bearing plate added.
11A. Similar to details 1 and 2.
11B. Alternate to detail 11A.
12. Similar to detail 3.
Group 4. Beam to Beam Connections Design concepts. Many variations of this type of con-
Slopes and skews require special attention to fabrication dimensions – well-designed connections provide adequate clearance to insert bolts or other connectors and also pro- vide room to grip and tighten with a wrench. Especially for sloped members, special attention is required to visualize
– some connections will induce large perpendicular to grain stresses in this mode.
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13. Bucket-style welded bracket at a “cross” junction. The top of the support beam is sometimes dapped to accom- modate the thickness of the steel.
14. Face-mounted hangers are commonly used in beam to beam connections. In a “cross” junction special attention is required to fastener penetration length into the carrying beam (to avoid interference from other side).
15. Deep members may be supported by fairly shallow hangers – in this case, through-bolted with shear plates. Clip angles are used to prevent rotation of the top of the suspended beam. Note that the clip angles are not con- nected to the suspended beam – doing so would restrain a deep beam from its natural across-the-grain shrinking and swelling cycles and would lead to splits.
16. Concealed connections similar to detail 5. The sus-
connection. The pin may be slightly narrower than the
suspended beam, permitting plugging of the holes after the pin is installed. Note that the kerf in the suspended beam must accommodate not only the width of the steel plate,
17. Similar to detail 13, with somewhat lower load capacity.
18. Clip angle to connect crossing beam.
19. Special detail to connect the ridge purlin to sloped members or to the peak of arch members.
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20A. Similar to detail 19, but with the segments of the
20B. Alternate to detail 20A.
Group 5. Cantilever Beam Connections
21. Hinge connector transfers load without need to slope cut member ends. Beams are often dapped top and bottom
Group 6. Arch Peak Connections
22. Steep arches connected with a rod and shear plates.
23. Similar to detail 22, with added shear plate.
24. Similar to detail 22 for low slope arches. Side plates replace the threaded rod.
Group 7. Arch Base to Support Design concepts. Arches transmit thrust into the sup-
porting structure. The foundation may be designed to resist this thrust or tie rods may be used. The base detail should be designed to accommodate the amount of rotation an- ticipated in the arch base under various loading conditions. Elastomeric bearing pads can assist somewhat in distrib- uting stresses. As noted earlier, the connection should be designed to minimize any perpendicular to grain stresses during the deformation of the structure under load.
25. Welded shoe transmits thrust from arch to support. Note that inside edge of shoe is left open to prevent col- lection of moisture.
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26. Arch base fastened directly to a steel tie beam in a shoe-type connection.
27. Similar to detail 25. This more rigid connection is suitable for spans where arch rotation at the base is small enough to not require the rotational movement permitted in detail 25. Note that, although the shoe is “boxed” a weep slot is provided at the inside face.
28. For very long spans or other cases where large rota- tions must be accommodated, a true hinge connection may be required.
Group 8. Moment Splice Design concepts. Moment splices must transmit axial
tension, axial compression, and shear. They must serve these functions in an area of the structure where structural
- duce cross-grain forces if they are to function properly.
- tion. Top and bottom plate transfer axial force, pressure plates transfer direct thrust, and shear plates transmit shear.
30. Similar to detail 29. Connectors on side faces may be easier to install, but forces are higher because moment arm between steel straps is less than in detail 29.
Group 9. Problem Connections Hidden column base. It is sometimes preferable ar-
chitecturally to conceal the connection at the base of the column. In any case it is crucial to detail this connection to minimize decay potential.
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78 M10: MECHANICAL CONNECTIONS
the top of the connection. THIS WILL CAUSE DECAY AND IS NOT A RECOMMENDED DETAIL!
31B. Alternate to detail 31A.
Full-depth side plates. It is sometimes easier to fab- ricate connections for deep beams from large steel plates rather than having to keep track of more pieces. Lack of attention to wood’s dimensional changes as it “breathes” may lead to splits.
32A. Full-depth side plates may appear to be a good con- nection option. Unfortunately, the side plates will remain
season. Since it is restrained by the side plates, the beam may split. THIS DETAIL IS NOT RECOMMENDED!
32B. As an alternative to detail 32A, smaller plates will transmit forces, but they do not restrain the wood from its natural movements.
Notched beam bearing. Depth limitations sometimes
solution is to notch the beam at the bearing. This induces large tension perpendicular to grain stresses and leads to splitting of the beam at the root of the notch.
33A. Notching a beam at its bearing may cause splits. THIS DETAIL IS NOT RECOMMENDED!
33B. Alternate to detail 33A.
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34A. This sloped bearing with a beam that is not fully supported may also split under load. THIS DETAIL IS NOT RECOMMENDED!
34B. Alternate to detail 34A.
Hanging to underside of beam. Sometimes it is ad- vantageous to hang a load from the underside of a beam. This is acceptable as long as the hanger is fastened to the upper half of the beam. Fastening to the lower half of the beam may induce splits.
35A. Connecting a hanger to the lower half of a beam that pulls downward may cause splits. THIS DETAIL IS NOT RECOMMENDED!
35B. As an alternative to detail 35A, the plates may be extended and the connection made to the upper half of the beam.
Hanger to side of beam. See full-depth side plates discussion.
36A. Deep beam hangers that have fasteners installed in the side plates toward the top of the supported beam may promote splits at the fastener group should the wood member shrink and lift from the bottom of the beam hanger because of the support provided by the fastener group. THIS DETAIL IS NOT RECOMMENDED!
36B. Alternate to detail 36A.
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80 M10: MECHANICAL CONNECTIONS
M10.5 Pre-Engineered Metal Connectors Product Information
Pre-engineered metal connectors for wood construc- tion are commonly used in all types of wood construction. There are numerous reasons for their widespread use. Connectors often make wood members easier and faster to install. They increase the safety of wood construction, not only from normal loads, but also from natural disasters such as earthquakes and high winds. Connectors make wood structures easier to design by providing simpler connections of known load capacity. They also allow for the use of more cost-effective engineered wood members by providing the higher capacity connections often re- quired by the use of such members. In certain locations,
hangers. Metal connectors are usually manufactured by stamp-
ing sheets or strips of steel, although some heavy hangers are welded together. Different thicknesses and grades of steel are used, depending on the required capacity of the connector.
Some metal connectors are produced as proprietary products which are covered by evaluation reports from one or all of the model building codes. Such reports should be consulted for current design information, while the manufacturer’s literature can be consulted for additional design information and detailed installation instructions.
Common Uses
Pre-engineered metal connectors for wood construc- tion are used throughout the world. Connectors are used to resist vertical dead, live, and snow loads; uplift loads from wind; and lateral loads from ground motion or wind. Almost any type of wood member may be fastened to another using a connector. Connectors may also be used to fasten wood to other materials, such as concrete, ma- sonry, or steel.
Availability
Connectors are manufactured in varying load ca-
applications. A variety of connectors are widely available through lumber suppliers.
Because of the wide variety of available connectors, a generic design document such as this must be limited in its
- nectors are available from the connector manufacturer.
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Types of Connectors Top Flange Joist Hangers -
along with the shear capacity of any fasteners that are present in the face. Although referred to as joist hangers, these connectors may support other horizontal members subject to vertical loads, such as beams or purlins.
Bent-style Joist, Beam, Top Flange and Purlin Hanger* I-joist Hanger*
Welded-type Purlin, Heavy Welded Beam Beam, and Joist Hanger* Hanger (Saddle Type)
There are many different types of connectors, due to the many different applications in which connectors may be used. The following sections list the most common types of connectors.
Face Mount Joist Hangers Face mount joist hangers install on the face of the
supporting member, and rely on the shear capacity of the nails to provide holding power. Although referred to as joist hangers, these connectors may support other hori- zontal members subject to vertical loads, such as beams or purlins.
Face Mount Heavy Face Mount Joist Hanger Joist Hanger
S SIM PSON ong-Tie
rt
Slope- and Skew- Face Mount Adjustable Joist Hanger I-Joist Hanger*
the joist. At a minimum, hanger support should extend to at least mid-height of a joist used with web stiffeners. Some connector manufacturers have developed
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82 M10: MECHANICAL CONNECTIONS
Adjustable Style Hanger Adjustable style joist and truss hangers have straps
which can be either fastened to the face of a supporting member, similar to a face mount hanger, or wrapped over
hanger.
Adjustable Style Truss Hangers
Flat Straps Flat straps rely on the shear capacity of the nails in the
wood members to transfer load.
@
Strap Used to Strap Used to Transfer Uplift Forces Transfer Lateral Forces
Seismic and Hurricane Ties Seismic and hurricane ties are typically used to connect
two members that are oriented 90º from each other. These ties resist forces through the shear capacity of the nails in the members. These connectors may provide resistance in three dimensions.
Seismic and Hurricane Ties
Connecting Roof Framing to Top Plates
Holddowns and Tension Ties Holddowns and tension ties usually bolt to concrete
or masonry, and connect wood members to the concrete or masonry through the shear resistance of either nails, screws, or bolts. They may also be used to connect two wood members together.
Holddown Tension Tie
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Purlin Anchor
Product Selection
Proper choice of connectors is required to optimize performance and economics. The selection of a connec- tor will depend on several variables. These include the following:
• capacity required • size and type of members being connected • species of wood being connected • slope and/or skew of member • connector type preference
Embedded Type Anchors Embedded anchors connect a wood member to con-
crete or masonry. One end of the connector embeds in the concrete or masonry, and the other end connects to the wood through the shear resistance of the nails or bolts.
Embedded Truss Anchor Embedded Nailed Holddown Strap
• type of fasteners to be used • corrosion resistance desired • appearance desired
Once the listed information is known, proper selection is facilitated through the use of manufacturer’s literature, code evaluation reports, and software available from con- nector manufacturers.
This Manual provides guidance for specifying pre-
criteria for a given application.
Connection Details
Connections, including pre-engineered metal con- nections, must provide the structural strength necessary to transfer loads. Well-designed connections hold wood members in such a manner that shrinkage/swelling cycles do not induce splitting across the grain. Well-designed con- nections also minimize collection of moisture – providing adequate clearance for air movement to keep the wood dry. Finally, well-designed connections minimize the potential for tension perpendicular to grain stresses – either under design conditions or under unusual loading conditions. Section M10.4 contains general concepts of well designed connections, including over 40 details showing acceptable and unacceptable practice.
Other Considerations
With proper selection and installation, structural con- nectors will perform as they were designed. However, proper selection and installation involves a variety of items that both the designer and the installer must consider including the general topics of: the wood members being connected; the fasteners used; and the connectors themselves. These items are discussed in the following sections. This Manual does not purport to address these topics in an all-inclusive manner – it is merely an attempt to alert designers to the importance of selection and installation details for achieving the published capacity of the connector.
Wood Members The wood members being connected have an impact
on the capacity of the connection. The following are im- portant items regarding the wood members themselves:
• The species of wood must be the same as that for which the connector was rated by the manufacturer. Manufac- turers test and publish allowable design values only for certain species of wood. For other species, consult with the connector manufacturer.
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84 M10: MECHANICAL CONNECTIONS
• The wood must not split when the fastener is installed. A fastener that splits the wood will not take the design load. If wood tends to split, consider pre-boring holes using a diameter not exceeding 3/4 of the nail diameter. Pre-boring requirements for screws and bolts are pro- vided in the NDS.
• Wood can shrink and expand as it loses and gains mois-
dry lumber dimensions. Other dimensions may be avail- able from the manufacturer.
• Where built-up lumber (multiple members) is installed in a connector, the members must be fastened together prior to installation of the connector so that the members act as a single unit.
• The dimensions of the supporting member must be -
fasteners. Refer to the connector manufacturer for other situations.
• Bearing capacity of the joist or beam should also be evaluated to ensure adequate capacity.
Fasteners Most wood connectors rely on the fasteners to transfer
the load from one member to the other. Therefore, the choice and installation of the fasteners is critical to the performance of the connector.
The following are important items regarding the fas- teners used in the connector:
• installed to achieve the published value.
• be installed. Most manufacturers specify common nails, unless otherwise noted.
• The fastener must have at least the same corrosion resistance as the connector.
• Bolts must generally be structural quality bolts, equal to or better than ANSI/ASME Standard B18.2.1.
• Bolt holes must be a minimum of 1/32" and a maximum of 1/16" larger than the bolt diameter.
• Fasteners must be installed prior to loading the connec- tion.
• injure the operator or others. Nail guns may be used to install connectors, provided the correct quantity and type of nails are properly installed in the manufacturer’s nail holes. Guns with nail hole-locating mechanisms should be used. Follow the nail gun manufacturer’s instructions and use the appropriate safety equipment.
Connectors Finally, the condition of the connector itself is critical
to how it will perform. The following are important items regarding the connector itself:
•
may cause fractures at the bend line, and fractured steel will not carry the rated load.
•
facturers. Contact the manufacturer to verify loads on
•
manufacturer regarding optional nail holes and optional loads.
• Different environments can cause corrosion of steel connectors. Always evaluate the environment where the connector will be installed. Connectors are avail- able with differing corrosion resistances. Contact the manufacturer for availability. Fasteners must be at least the same corrosion resistance as that chosen for the connector.
85ASD/LRFD MANUAL FOR ENGINEERED WOOD CONSTRUCTION
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M11: DOWEL- TYPE FASTENERS
M11.1 General 86
M11.2 Reference Withdrawal Design Values 86
M11.3 Reference Lateral Design Values 86
M11.4 Combined Lateral and Withdrawal Loads 86
M11.5 Adjustment of Reference Design Values 87
M11.6 Multiple Fasteners 87
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86 M11: DOWEL-TYPE FASTENERS
This Chapter covers design of connections between wood members using metal dowel-type (nails, bolts, lag screws, wood screws, drift pins) fasteners.
These connectors rely on metal-to-wood bearing for transfer of lateral loads and on friction or mechanical interfaces for transfer of axial (withdrawal) loads. They are commonly available in a wide range of diameters and lengths.
M11.2 Reference Withdrawal Design Values
The basic design equation for dowel-type fasteners under withdrawal loads is:
W p RW where: W = adjusted withdrawal design value
RW = axial (withdrawal) force
p = depth of fastener penetration into wood member
Reference withdrawal design values are tabulated in NDS Chapter 11.
M11.3 Reference Lateral Design Values
The basic equation for design of dowel-type fasteners under lateral load is:
Z RZ where: Z = adjusted lateral design value
RZ = lateral force Reference lateral design values are tabulated in NDS
Chapter 11.
M11.4 Combined Lateral and Withdrawal Loads
Lag screws, wood screws, nails, and spikes resisting combined lateral and withdrawal loads shall be designed in accordance with NDS 11.4.
M11.1 General
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M11.5 Adjustment of Reference Design Values
M11.6 Multiple Fasteners Local stresses in connections using multiple fasteners
can be evaluated in accordance with NDS Appendix E.
Dowel-type connections must be designed by ap- plying all applicable adjustment factors to the reference withdrawal design value or reference lateral design value for the connection. NDS Table 10.3-1 lists all applicable adjustment factors for dowel-type connectors. Table M11.3-1 shows the applicability of adjustment factors for dowel-type fasteners in a slightly different format for the designer.
Example of a Dowel-Type Fastener Loaded Laterally
For a single dowel-type fastener installed in side grain perpendicular to the length of the wood member, meeting the end and edge distance and spacing requirements of NDS 11.5.1, used in a normal building environment (meeting the reference conditions of NDS 2.3 and 10.3), and not a nail or spike in diaphragm construction, the general equation for Z reduces to:
for ASD: Z = Z CD for LRFD: Z = Z KF z
Table M11.3-1 Applicability of Adjustment Factors for Dowel-Type Fasteners1
Allowable Stress Design Load and Resistance Factor Design Lateral Loads
Dowel-Type Fasteners Z = Z CD CM Ct Cg C Ceg Cdi Ctn Z = Z CM Ct Cg C Ceg Cdi Ctn KF z Withdrawal Loads
Nails, Spikes, Lag Screws, Wood Screws, and Drift Pins W = W CD CM Ct Ceg Ctn Z = Z CM Ct Ceg Ctn KF z
1. See NDS Table 10.3.1 footnotes for additional guidance on application of adjustment factors for dowel-type fasteners.
Example of a Dowel-Type Fastener Loaded in Withdrawal
For a single dowel-type fastener installed in side grain perpendicular to the length of the wood member, used in a normal building environment (meeting the reference conditions of NDS 2.3 and 10.3), the general equation for W reduces to:
for ASD: W = W CD for LRFD: W = W KF z
Installation Requirements
To achieve stated design values, connectors must comply with installation requirements such as spacing of connectors, minimum edge and end distances, proper drill- ing of lead holes, and minimum fastener penetration.
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M11: DOWEL-TYPE FASTENERS88
89ASD/LRFD MANUAL FOR ENGINEERED WOOD CONSTRUCTION
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M12: SPLIT RING AND SHEAR PLATE CONNECTORS
M12.1 General 90
M12.2 Reference Design Values 90
M12.3 Placement of Split Ring and Shear Plate Connectors 90
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90 M12: SPLIT RING AND SHEAR PLATE CONNECTORS
For a single split ring or shear plate connection in- stalled in side grain perpendicular to the length of the wood members, meeting the end and edge distance and spacing requirements of NDS 12.3, used in a normal building envi- ronment (meeting the reference conditions of NDS 2.3 and 10.3), and meeting the penetration requirements of NDS 12.2.3, the general equations for P and Q reduce to:
M12.1 General This Chapter covers design for split rings and shear
plates. These connectors rely on their geometry to provide larger metal-to-wood bearing areas per connector. Both are installed into precut grooves or daps in the members.
M12.2 Reference Design Values
Reference lateral design values (P, Q) are tabulated in the split ring and shear plate tables in NDS 12.2.
Design Adjustment Factors
Split ring and shear plate connections must be designed by applying all applicable adjustment factors to the refer- ence lateral design value for the connection. NDS Table
Table M12.2-1 Applicability of Adjustment Factors for Split Ring and Shear Plate Connectors1
Allowable Stress Design Load and Resistance Factor Design
Split Ring and Shear Plate Connectors
P = P CD CM Ct Cg C Cd Cst P = P CM Ct Cg C Cd Cst KF z Q = Q CD CM Ct Cg C Cd Q = Q CM Ct Cg C Cd KF z
1. See NDS Table 10.3.1 footnotes for additional guidance on application of adjustment factors for split ring and shear plate connectors.
10.3.1 provides all applicable adjustment factors for split ring and shear plate connectors. Table M12.2-1 shows the applicability of adjustment factors for dowel-type fasteners in a slightly different format for the designer.
M12.3 Placement of Split Ring and Shear Plate Connectors Installation Requirements
To achieve stated design values, connectors must comply with installation requirements such as spacing of connectors, minimum edge and end distances, proper dapping and grooving, drilling of lead holes, and minimum
NDS 12.3.
for ASD: P = P CD
Q = Q CD
for LRFD: P = P KF z
Q = Q KF z
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M13: TIMBER RIVETS
M13.1 General 92
M13.2 Reference Design Values 92
M13.3 Placement of Timber Rivets 92
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M13.3 Placement of Timber Rivets Installation Requirements
To achieve stated design values, connectors must comply with installation requirements such as spacing of connectors, minimum edge and end distances per NDS 13.3; and drilling of lead holes, minimum fastener penetra- tion, and other fabrication requirements per NDS 13.1.2.
For a timber rivet connection installed in side grain perpendicular to the length of the wood members, with metal side plates 1/4" or greater, used in a normal building environment (meeting the reference conditions of NDS 2.3 and 10.3), and where wood capacity perpendicular to grain, Qw , does not control, the general equations for P and Q reduce to:
M13.1 General This Chapter covers design for timber rivets. Timber
rivets are hardened steel nails that are driven through pre- drilled holes in steel side plates (typically 1/4" thickness) to form an integrated connection where the plate and rivets work together to transfer load to the wood member.
M13.2 Reference Design Values Reference wood capacity design values parallel to
grain, Pw , are tabulated in the timber rivet Tables 13.2.1A through 13.2.1F in the NDS.
Reference design values perpendicular to grain are calculated per NDS 13.2.2.
Design Adjustment Factors
Connections must be designed by applying all applica- ble adjustment factors to the reference lateral design value
Table M13.2-1 Applicability of Adjustment Factors for Timber Rivets1
Allowable Stress Design Load and Resistance Factor Design
Timber Rivets P = P CD CM Ct Cst P = P CM Ct Cst KF z Q = Q CD CM Ct C Q = Q CM Ct C KF z
1. See NDS Table 10.3.1 footnotes for additional guidance on application of adjustment factors for timber rivets.
for the connection. NDS Table 10.3-1 lists all applicable adjustment factors for timber rivets. Table M13.2-1 shows the applicability of adjustment factors for timber rivets in a slightly different format for the designer.
for ASD: P = P CD
Q = Q CD
for LRFD: P = P KF z
Q = Q KF z
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M14: SHEAR WALLS AND DIAPHRAGMS
M14.1 General 94
M14.2 Design Principles 94
M14.3 Shear Walls 97
M14.4 Diaphragms 98
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94 M14: SHEAR WALLS AND DIAPHRAGMS
M14.2 Design Principles
Drag Struts/Collectors
The load path for a box-type structure is from the dia- phragm into the shear walls running parallel to the direction of the load (i.e., the diaphragm loads the shear walls that support it). Because the diaphragm acts like a long, deep beam, it loads each of the supporting shear walls evenly along the length of the walls. However, a wall typically contains windows and doors.
The traditional model used to analyze shear walls only recognizes full height wall segments as shear wall seg- ments. This means that at locations with windows or doors, a structural element is needed to distribute diaphragm shear over the top of the opening and into the full height segments adjacent to it. This element is called a drag strut (see Figure M14.2-1).
In residential construction, the double top-plates ex- isting in most stud walls will serve as a drag strut. It may be necessary to detail the double top plate such that no splices occur in critical zones. Or, it may be necessary to specify the use of a tension strap at butt joints to transfer these forces.
The maximum force seen by drag struts is generally equal to the diaphragm design shear in the direction of the shear wall multiplied by the distance between shear wall segments.
Drag struts are also used to tie together different parts of an irregularly shaped building.
To simplify design, irregularly shaped buildings (such as “L” or “T” shaped) are typically divided into simple rectangles. When the structure is “reassembled” after the individual designs have been completed, drag struts are used to provide the necessary continuity between these individual segments to insure that the building will act as a whole.
Figures M14.2-1, M14.2-2, and M14.2-3 and the ac- companying generalized equations provide methods to calculate drag strut forces.
Figure M14.2-1 Shear Wall Drag Strut
Unit shear above opening = V L
va
Unit shear below opening = V L L
vb 0
Max. force in drag strut = greater of
V L
L L
L L v L L L L
a o 0 1
0
1
0( ) ( )
or
V L
L L
L L v L L L L
a o 0 2
0
2
0( ) ( )
M14.1 General This Chapter pertains to design of shear walls and
diaphragms. These assemblies, which transfer lateral forces (wind and seismic) within the structure, are com- monly designed using panel products fastened to framing members. The use of bracing systems to transfer these forces is not within the scope of this Chapter.
Shear wall/diaphragm shear capacity is tabulated in the ANSI/AF&PA Special Design Provisions for Wind and Seismic (SDPWS) Supplement.
V
L 1 L 2L O
L
Elevation
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L1LO
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Figure M14.2-2 Shear Wall Special Case Drag Strut
Unit shear above opening = V L
va
Unit shear below opening = V L
vb 1
Maximum force in drag strut = L vo a
Figure M14.2-3 Diaphragm Drag Strut (Drag strut parallel to loads)
Unit shear along L W L
L3 1 1
32
Force in drag strut from L3 structure = W L
L L1 1
3 52
( )
Unit shear along L W L
L4 2 2
42
Force in drag strut from L4 structure = W L
L L2 2
4 52
( )
Maximum force in drag strut = L W L L
W L L
5 1 1
3
2 2
42
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Chords
Diaphragms are assumed to act like long deep beams. This model assumes that shear forces are accommodated by the structural-use panel web of the “beam” and that moment forces are carried by the tension or compression
chord forces are often assumed to be carried by the double top-plate of the supporting perimeter walls. Given the magnitude of forces involved in most light-frame wood
capacity to resist tensile and compressive forces assum- ing adequate detailing at splice locations. However, offset wall lines and other factors sometimes make a continuous diaphragm chord impossible.
Because shear walls act as blocked, cantilevered dia- phragms, they too develop chord forces and require chords. The chords in a shear wall are the double studs that are required at the end of each shear wall. Just as chords need to be continuous in a diaphragm, chords in a shear wall also need to maintain their continuity. This is accomplished by tension ties (holddowns) that are required at each end of each shear wall and between chords of stacked shear walls to provide overturning restraint. Figure M14.2-4 and the accompanying generalized equations provide a method to calculate chord forces.
Diaphragm reaction = Lw 2
Diaphragm unit shear = Lw L2 2
Diaphragm moment = wL2
8
Maximum chord force = wL
L
2
28
Chord force at point x, F(x) = wLx
L wx
L2 22
2
2
L
Unit Load (wind or seismic) w
L2
x
F(x)
F(x)
Figure M14.2-4 Diaphragm Chord Forces
Plan
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h
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T C
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M14.3 Shear Walls
Overturning
Overturning moments result from shear walls being loaded by horizontal forces. Overturning moments are resisted by force couples. The tension couple is typically achieved by a holddown. Figure M14.3-1 and the ac- companying equations present a method for calculating overturning forces for a non-load-bearing wall. Figure M14.3-2 and the accompanying equations present a method for calculating overturning forces for a load-bear- ing wall. Overturning forces for load-bearing walls can utilize dead load as overturning restraint. To effectively resist uplift forces, holddown restraints are required to show very little slip relative to the chord (end post).
Figure M14.3-1 Overturning Forces (no dead load)
Unit shear = V L
v
Overturning force = chord force = Vh L
Overturning moment = Ph
Dead load restraining moment* = wL2
2
Net overturning moment = Ph wL2
2
Net overturning force – chord force = Ph wL
L Ph L
wL
2
2 2
* See building code for applicable reduction to the dead load restraining mo- ment to insure an appropriate load factor for overturning.
Figure M14.3-2 Overturning Forces (with dead load)
Elevation
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98 M14: SHEAR WALLS AND DIAPHRAGMS
Subdiaphragms
The subdiaphragm (also known as the mini-dia- phragm) concept has been recognized and extensively used to provide a method of meeting wall attachment and continuous cross-tie code requirements while minimizing the number and length of ties required to achieve continu-
can be found in SDPWS, “SUBDIAPHRAGM portion of a larger wood diaphragm designed to anchor and transfer local forces to primary diaphragm struts and the main diaphragm.”
In practice, the subdiaphragm approach is used to concentrate and transfer local lateral forces to the main structural members that support vertical loads. The subdia- phragm approach is often an economical solution to code required cross-ties for the following reasons:
• Main structural members are already present • Main structural members generally span the
full length and width of the buildings with few connectors.
• Main structural members are large enough to easily accommodate loads.
• Main structural members are large enough to allow “room” for requisite connections.
M14.4 Diaphragms
Each subdiaphragm must meet all applicable dia- phragm requirements provided in the applicable building code. As such, each subdiaphragm must have chords,
and attachment to transfer shear stresses generated within the diaphragm sheathing by the subdiaphragm. In addition,
to subdiaphragms. The subdiaphragm is actually the same structure as
the main roof diaphragm, thus the subdiaphragm utilizes the same roof sheathing to transfer shear stresses as the main diaphragm. As such, sheathing nailing and thickness
for the subdiaphragm requirements. In this case, the sub- diaphragm requirements would control and dictate roof sheathing and fastening requirements in subdiaphragm locations. Fortunately, the portion of the main diaphragm that is utilized as a subdiaphragm is a choice left to the designer; thus dimensions of the subdiaphragm can be chosen to minimize potential discontinuities in sheathing thicknesses or nail schedules. Similarly, the roof dia- phragm requirements may be more stringent than those for the subdiaphragm.
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M15: SPECIAL LOADING CONDITIONS
M15.1 Lateral Distribution of Concentrated Loads 100
M15.2 Spaced Columns 100
M15.3 Built-Up Columns 100
M15.4 Wood Columns with Side Loads and Eccentricity 100
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100 M15: SPECIAL LOADING CONDITIONS
M15.1 Lateral Distribution of Concentrated Loads
M15.2 Spaced Columns
M15.1.2 Lateral Distribution of a Concentrated Load for Shear
The lateral distribution factors for shear in NDS Table 15.1.2 relate the lateral distribution of concentrated load at the center of the beam or stringer span as determined under NDS 15.1.1, or by other means, to the distribution of load at the quarter points of the span. The quarter points are considered to be near the points of maximum shear in the stringers for timber bridge design.
M15.1.1 Lateral Distribution of a Concentrated Load for Moment
The lateral distribution factors for moment in NDS Table 15.1.1 are keyed to the nominal thickness of the
the stringers or beams is based on recommendations of the American Association of State Highway and Transporta-
Lateral distribution factors determined in accordance with NDS or moving concentrated load.
As used in the NDS, spaced columns refer to two or more individual members oriented with their longitudinal axis parallel, separated at the ends and in the middle por- tion of their length by blocking and joined at the ends by split ring or shear plate connectors capable of developing required shear resistance.
M15.3 Built-Up Columns
M15.4 Wood Columns with Side Loads and Eccentricity
As with spaced columns, built-up columns obtain
individual laminations. The closer the laminations of a mechanically fastened built-up column deform together (the smaller the amount of slip occurring between lami- nations) under compressive load, the greater the relative capacity of that column compared to a simple solid column of the same slenderness ratio made with the same quality of material.
The eccentric load design provisions of NDS 15.4.1 are not generally applied to columns supporting beam loads where the end of the beam bears on the entire cross section of the column. It is standard practice to consider such loads to be concentrically applied to the supporting
provided by the end of the column is ignored when the usual pinned end condition is assumed in column design. In applications where the end of the beam does not bear on the full cross section of the supporting column, or in
blocks increases the load-carrying capacity in compres- sion parallel to grain of the individual members only in the direction perpendicular to their wide faces.
AF&PA’s Wood Structural Design Data (WSDD) provides load tables for spaced columns.
special critical loading cases, use of the eccentric column loading provisions of NDS 15.4.1 may be considered ap- propriate by the designer.
101ASD/LRFD MANUAL FOR ENGINEERED WOOD CONSTRUCTION
AMERICAN FOREST & PAPER ASSOCIATION
M16: FIRE DESIGN
M16.1 General 102
Lumber 103
Structural Glued Laminated Timber 119
Poles and Piles 120
Structural Composite Lumber 121
Wood I-Joists 122
Metal Plate Connected Wood Trusses 131
M16.2 Design Procedures for Exposed Wood Members 145
M16.3 Wood Connections 159
16
AMERICAN WOOD COUNCIL
102 M16: FIRE DESIGN
M16.1 General
Table M16.1-1 Minimum Sizes to Qualify as Heavy Timber Construction
Material Minimum size (nominal size or thickness)
Roof decking: Lumber or structural- use panels
2 in. thickness l-l/8 in. thickness
Floor decking: Lumber
or structural-use panels
3 in. thickness 1 in. thickness 1/2 in. thickness
Roof framing: 4 by 6 in. Floor framing: 6 by 10 in. Columns:
6 by 8 in. (supporting roofs)
wood products. Lumber, glued laminated timber, poles and piles, wood I-joists, structural composite lumber, and metal plate connected wood trusses are discussed.
Planning
a proposed building is to be constructed must be consulted
normally concerns the type of construction desired as well as allowable building areas and heights for each construc- tion type.
types such as wood frame (Type V), noncombustible or
and roofs of wood stud and joist framing of 2" nominal dimension. These are divided into two subclasses that are either protected or unprotected construction. Protected construction calls for having load-bearing assemblies of
Type III construction has exterior walls of noncom-
partitions of wood frame. As in Type V construction, these are divided into two subclasses that are either protected or unprotected.
Type IV construction includes exterior walls of non-
a minimum size, as shown in Table M16.1-1. In addition to having protected and unprotected sub-
- tion, such as sprinkler protection systems, are included. For example, protected wood-frame business occupancies can be increased from three to four stories in height because
be further increased under some conditions. Additional information is available at www.awc.org.
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16Table M16.1-3 Two-Hour Fire-Rated Load-Bearing Wood-Frame Wall Assemblies
Table M16.1-2 One-Hour Fire-Rated Load-Bearing Wood-Frame Wall Assemblies
Assemblies Rated From Both Sides Studs Insulation Sheathing on Both Sides Fasteners Details 2x4 @ 16" o.c. 3½" mineral wool batts 5/8" Type X Gypsum Wallboard (H) 2¼" #6 Type S drywall screws @ 12" o.c. Figure M16.1-1
2x6 @ 16" o.c. (none) 5/8" Type X Gypsum Wallboard (H) 2¼" #6 Type S drywall screws @ 7" o.c. Figure M16.1-2
2x6 @ 16" o.c. 5½" mineral wool batts 5/8" Type X Gypsum Wallboard (H) 2¼" #6 Type S drywall screws @ 12" o.c. Figure M16.1-3
2x6 @ 16" o.c. 5/8" Type X Gypsum Wallboard (V) 2¼" #6 Type S drywall screws @ 12" o.c. Figure M16.1-4
Assemblies Rated From One Side (Fire on Interior Only) Studs Insulation Sheathing Fasteners Details
2x4 @ 16" o.c. 3½" mineral wool batts I 5/8" Type X Gypsum Wallboard (H) 2¼" #6 Type S drywall screws @ 12" o.c.
Figure M16.1-5 E 3/8" wood structural panels (V)
2x4 @ 16" o.c. 4 mil polyethylene 3½" mineral wool batts
I 5/8" Type X Gypsum Wallboard (V) 6d cement coated box nails @ 7" o.c.
Figure M16.1-6 E
V)
3/8" hardboard shiplapped panel siding
2x6 @ 16" o.c. 5½" mineral wool batts I 5/8" Type X Gypsum Wallboard (H) 2¼" #6 Type S drywall screws @ 12" o.c.
Figure M16.1-7 E 7/16" wood structural panels (V)
2x6 @ 16" o.c. I 5/8" Type X Gypsum Wallboard (V) 2¼" #6 Type S drywall screws @ 12" o.c.
Figure M16.1-8 E 3/8" wood structural panels (V)
H- applied horizontally with vertical joints over studs; I- Interior sheathing; V- applied vertically with vertical joints over studs; E- Exterior sheathing
Assemblies Rated From Both Sides Studs Insulation Sheathing on Both Sides Fasteners Details
2x4 @ 24" o.c. 5½" mineral wool batts B 5/8" Type X Gypsum Wallboard (H) 2¼" #6 Type S drywall screws @ 24" o.c.
Figure M16.1-9 F 5/8" Type X Gypsum Wallboard (H) 2¼" #6 Type S drywall screws @ 8" o.c.
H- applied horizontally with vertical joints over studs; B- Base layer sheathing: F- Face layer sheathing
Building Code Requirements
and other commercial and industrial uses, building codes
Depending on the application, wall assemblies may need to be rated either from one side or both sides. For
International Build- ing Code (IBC) allows wood-frame, wood-sided walls to be
both interior and exterior exposure is only required when the
recognition of 1- and 2-hour wood-frame wall systems is
accordance with ASTM E119, Standard Test Methods for Fire Tests of Building Construction Materials.
Fire Tested Assemblies Fire-rated wood-frame assemblies can be found in a
number of sources including the IBC, Underwriters Labo- ratories (UL) Fire Resistance Directory, Intertek Testing Services’ Directory of Listed Products, and the Gypsum Association’s Fire Resistance Design Manual. The Ameri- can Forest & Paper Association (AF&PA) and its members
Descriptions of these successfully tested assemblies are provided in Tables M16.1-2 through M16.1-5.
Updates Additional tests are being conducted and the Tables
will be updated periodically. AF&PA’s Design for Code Acceptance (DCA) No. 3, Fire Rated Wood Floor and Wall Assemblies incorporates many of these assemblies and is available at www.awc.org.
Lumber
AMERICAN WOOD COUNCIL
104 M16: FIRE DESIGN
Table M16.1-5 Two-Hour Fire-Rated Wood Floor/Ceiling Assemblies
Table M16.1-4 One-Hour Fire-Rated Wood Floor/Ceiling Assemblies
Joists Insulation Furring Ceiling Sheathing Floor Sheathing Details
2x10 @ 16" o.c. none Optional F 5/8" Type X Gypsum Wallboard or ½" Type X Gypsum Wallboard
-
paper, and Nom. 1" T&G boards or 15/32" Figure M16.1-10
2x10 @ 16" o.c. none (none) F ½" x 24" x 48" mineral acoustical ceiling panels (see grid details)
Nom. 19/32" T&G plywood* underlayment - Figure M16.1-11
2x10 @ 16" o.c. none Resilient channels F 5/8" Type X Gypsum Wallboard or ½" proprietary Type Gypsum Wallboard
Nom. 19/32" T&G plywood* underlayment Figure M16.1-12
2x10 @ 24" o.c. none Resilient channels F 5/8" proprietary Type Gypsum Wallboard
Nom. 23/32" T&G plywood* underlayment Figure M16.1-13
F
Joists Insulation Furring Ceiling Sheathing Floor Sheathing Details
2x10 @ 16" o.c. none
(none) B 5/8" proprietary Type X Gypsum Wallboard -
paper, and Nom. 1" T&G boards or 15/32" plywood*
Figure M16.1-14 Resilient channels F
5/8" proprietary Type X Gypsum Wallboard
B- Base layer sheathing (direct attached); F designs may be nom. 7/16" OSB.
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1. Framing: Nominal 2x4 wood studs, spaced 16 in. o.c., double top plates, single bottom plate.
2. Sheathing: 5/8 in. Type X gypsum wallboard, 4 ft. wide, applied horizontally, unblocked. Horizontal ap- plication of wallboard represents the direction of least
3. Insulation: 3-1/2 in. thick mineral wool insulation. 4. Fasteners: 2-1/4 in. Type S drywall screws, spaced
12 in. o.c. 5. Joints and Fastener Heads: Wallboard joints covered
with paper tape and joint compound, fastener heads covered with joint compound.
This assembly was tested at 100% design load, calculated in accordance with the National Design
. The authority having jurisdiction should be consulted to assure acceptance of this report.
Figure M16.1-1 One-Hour Fire-Resistive Wood Wall Assembly (WS4-1.1) 2x4 Wood Stud Wall - 100% Design Load - ASTM E119/NFPA 251
Tests conducted at the Fire Test Laboratory of National Gypsum Research Center
Test No: WP-1248 (Fire Endurance), March 29, 2000
WP-1246 (Hose Stream), March 9, 2000 Third-Party Witness: Intertek Testing Services Report J20-06170.1
AMERICAN WOOD COUNCIL
106 M16: FIRE DESIGN
This assembly was tested at 100% design load, calculated in accordance with the National Design
. The authority having jurisdiction should be consulted to assure acceptance of this report.
Figure M16.1-2 One-Hour Fire-Resistive Wood Wall Assembly (WS6-1.1) 2x6 Wood Stud Wall - 100% Design Load - ASTM E119/NFPA 251
1. Framing: Nominal 2x6 wood studs, spaced 16 in. o.c., double top plates, single bottom plate.
2. Sheathing: 5/8 in. Type X gypsum wallboard, 4 ft. wide, applied horizontally, unblocked. Horizontal ap- plication of wallboard represents the direction of least
3. Fasteners: 2-1/4 in. Type S drywall screws, spaced 7 in. o.c.
4. Joints and Fastener Heads: Wallboard joints covered with paper tape and joint compound, fastener heads covered with joint compound.
Tests conducted at the Fire Test Laboratory of National Gypsum Research Center
Test No: WP-1232 (Fire Endurance), September 16, 1999
WP-1234 (Hose Stream), September 27, 1999 Third-Party Witness: Intertek Testing Services Report J99-22441.2
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This assembly was tested at 100% design load, calculated in accordance with the National Design
. The authority having jurisdiction should be consulted to assure acceptance of this report.
1. Framing: Nominal 2x6 wood studs, spaced 16 in. o.c., double top plates, single bottom plate.
2. Sheathing: 5/8 in. Type X gypsum wallboard, 4 ft. wide, applied horizontally, unblocked. Horizontal ap- plication of wallboard represents the direction of least
3. Insulation: 5-1/2 in. thick mineral wool insulation. 4. Fasteners: 2-1/4 in. Type S drywall screws, spaced
12 in. o.c. 5. Joints and Fastener Heads: Wallboard joints covered
with paper tape and joint compound, fastener heads covered with joint compound.
Figure M16.1-3 One-Hour Fire-Resistive Wood Wall Assembly (WS6-1.2) 2x6 Wood Stud Wall - 100% Design Load - ASTM E119/NFPA 251
Tests conducted at the Fire Test Laboratory of National Gypsum Research Center
Test No:WP-1231 (Fire Endurance), September 14, 1999
WP-1230 (Hose Stream), August 30, 1999 Third-Party Witness: Intertek Testing Services Report J99-22441.1
AMERICAN WOOD COUNCIL
108 M16: FIRE DESIGN
Figure M16.1-4 One-Hour Fire-Resistive Wood Wall Assembly (WS6-1.4) 2x6 Wood Stud Wall - 100% Design Load - ASTM E119/NFPA 251
1. Framing: Nominal 2x6 wood studs, spaced 16 in. o.c., double top plates, single bottom plate
2. Sheathing: 5/8 in. Type X gypsum wallboard, 4 ft. wide, applied vertically. All panel edges backed by framing or blocking.
3. Insulation 4. Fasteners: 2-1/4 in. Type S drywall screws, spaced
12 in. o.c. 5. Joints and Fastener Heads: Wallboard joints covered
with paper tape and joint compound, fastener heads covered with joint compound.
Tests conducted at NGC Testing Services
Test No: WP-1346 (Fire Endurance), August 22, 2003
WP-1351 (Hose Stream), September 17, 2003 Third-Party Witness: NGC Testing Services
This assembly was tested at 100% design load, calculated in accordance with the National Design
. The authority having jurisdiction should be consulted to assure acceptance of this report.
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This assembly was tested at 100% design load, calculated in accordance with the National Design
. The authority having jurisdiction should be consulted to assure acceptance of this report.
Figure M16.1-5 One-Hour Fire-Resistive Wood Wall Assembly (WS4-1.2) 2x4 Wood Stud Wall - 100% Design Load - ASTM E119/NFPA 251
1. Framing: Nominal 2x4 wood studs, spaced 16 in. o.c., double top plates, single bottom plate.
2. Interior Sheathing: 5/8 in. Type X gypsum wallboard, 4 ft. wide, applied horizontally, unblocked. Horizontal application of wallboard represents the direction of
- tion.
3. Exterior Sheathing: 3/8 in. wood structural panels (oriented strand board), applied vertically, horizontal joints blocked.
4. Gypsum Fasteners: 2-1/4 in. Type S drywall screws, spaced 12 in. o.c.
5. Panel Fasteners: 6d common nails (bright): 12 in.
6. Insulation: 3-1/2 in. thick mineral wool insulation. 7. Joints and Fastener Heads: Wallboard joints covered
with paper tape and joint compound, fastener heads covered with joint compound.
Tests conducted at the Fire Test Laboratory of National Gypsum Research Center
Test No: WP-1261 (Fire Endurance & Hose Stream), November 1, 2000
Third-Party Witness: Intertek Testing Services Report J20-006170.2
AMERICAN WOOD COUNCIL
110 M16: FIRE DESIGN
Figure M16.1-6 One-Hour Fire-Resistive Wood Wall Assembly (WS4-1.3) 2x4 Wood Stud Wall - 78% Design Load - ASTM E119/NFPA 251
1. Framing: Nominal 2x4 wood studs, spaced 16 in. o.c., double top plates, single bottom plate.
2. Interior Sheathing: 5/8 in. Type X gypsum wallboard, 4 ft. wide, applied vertically, unblocked.
3. Exterior Sheathing: Alternate construction: minimum 1/2 in. lumber siding or 1/2 in. wood-based sheathing.
4. Exterior Siding: 3/8 in. hardboard shiplap edge panel siding. Alternate construction lumber or wood-based, vinyl, or aluminum siding.
5. Vapor Barrier: 4-mil polyethylene sheeting. 6. Insulation: 3-1/2 in. thick mineral wool insulation. 7. Gypsum Fasteners: 6d cement coated box nails
spaced 7 in. o.c. 8. Fiberboard Fasteners:
9. Hardboard Fasteners: 8d galvanized nails: 8 in. o.c.
10. Joints and Fastener Heads: Wallboard joints covered with paper tape and joint compound, fastener heads covered with joint compound.
Tests conducted at the Gold Bond Building Products Fire Testing Laboratory
Test No: WP-584 (Fire Endurance & Hose Stream), March 19, 1981
Third-Party Witness: Warnock Hersey International, Inc.
Report WHI-690-003
This assembly was tested at 78% design load using an e/d of 33, calculated in accordance with the 1997
- tion. The authority having jurisdiction should be consulted to assure acceptance of this report.
AMERICAN FOREST & PAPER ASSOCIATION
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Figure M16.1-7 One-Hour Fire-Resistive Wood Wall Assembly (WS6-1.3) 2x6 Wood Stud Wall - 100% Design Load - ASTM E119/NFPA 251
This assembly was tested at 100% design load, calculated in accordance with the National Design
. The authority having jurisdiction should be consulted to assure acceptance of this report.
1. Framing: Nominal 2x6 wood studs, spaced 16 in. o.c., double top plates, single bottom plate.
2. Interior Sheathing: 5/8 in. Type X gypsum wallboard, 4 ft. wide, applied horizontally, unblocked. Horizontal application of wallboard represents the direction of
- tion.
3. Exterior Sheathing: 7/16 in. wood structural panels (oriented strand board), applied vertically, horizontal joints blocked.
4. Gypsum Fasteners: 2-1/4 in. Type S drywall screws, spaced 12 in. o.c.
5. Panel Fasteners: 6d common nails (bright): 12 in.
6. Insulation: 5-1/2 in. thick mineral wool insulation. 7. Joints and Fastener Heads: Wallboard joints covered
with paper tape and joint compound, fastener heads covered with joint compound.
Tests conducted at the Fire Test Laboratory of National Gypsum Research Center
Test No: WP-1244 (Fire Endurance & Hose Stream), February 25, 2000
Third-Party Witness: Intertek Testing Services Report J99-27259.2
AMERICAN WOOD COUNCIL
112 M16: FIRE DESIGN
Figure M16.1-8 One-Hour Fire-Resistive Wood Wall Assembly (WS6-1.5) 2x6 Wood Stud Wall - 100% Design Load - ASTM E119/NFPA 25
1. Framing: Nominal 2x6 wood studs, spaced 16 in. o.c., double top plates, single bottom plate.
2. Interior Sheathing: 5/8 in. Type X gypsum wallboard, 4 ft. wide, applied vertically. All panel edges backed by framing or blocking.
3. Exterior Sheathing: 3/8 in. wood structural panels (oriented strand board), applied vertically, horizontal joints blocked.
4. Gypsum Fasteners: 2-1/4 in. Type S drywall screws, spaced 7 in. o.c.
5. Panel Fasteners: 6d common nails (bright) - 12 in.
6. Insulation: 7. Joints and Fastener Heads: Wallboard joints covered
with paper tape and joint compound, fastener heads covered with joint compound.
Tests conducted at the NGC Testing Services
Test No: WP-1408 (Fire Endurance & Hose Stream) August 13, 2004 Third-Party Witness: NGC Testing Services
This assembly was tested at 100% design load, calculated in accordance with the National Design
. The authority having jurisdiction should be consulted to assure acceptance of this report.
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Figure M16.1-9 Two-Hour Fire-Resistive Wood Wall Assembly (WS6-2.1) 2x6 Wood Stud Wall - 100% Design Load - ASTM E119/NFPA 251
1. Framing: Nominal 2x6 wood studs, spaced 24 in. o.c., double top plates, single bottom plate.
2. Sheathing: Base Layer: 5/8 in. Type X gypsum wallboard, 4 ft. wide,
applied horizontally, unblocked. Face Layer: 5/8 in. Type X gypsum wallboard, 4 ft. wide,
applied horizontally, unblocked. Horizontal applica-
resistance as opposed to vertical application. 3. Insulation: 5-1/2 in. thick mineral wool insulation. 4. Gypsum Fasteners: Base Layer: 2-1/4 in. Type S
drywall screws, spaced 24 in. o.c. 5. Gypsum Fasteners: Face Layer: 2-1/4 in. Type S
drywall screws, spaced 8 in. o.c. 6. Joints and Fastener Heads: Wallboard joints covered
with paper tape and joint compound, fastener heads covered with joint compound.
Tests conducted at the Fire Test Laboratory of National Gypsum Research Center
Test No: WP-1262 (Fire Endurance), November 3, 2000
WP-1268 (Hose Stream), December 8, 2000 Third-Party Witness: Intertek Testing Services Report J20-006170.3
This assembly was tested at 100% design load, calculated in accordance with the National Design
. The authority having jurisdiction should be consulted to assure acceptance of this report.
AMERICAN WOOD COUNCIL
114 M16: FIRE DESIGN
1. -
board (OSB) panels are permitted for certain de- signs.
2. Building paper. 3. Nominal 1 in. T&G boards or 15/32 in. plywood sub-
7/16 in. OSB. 4. 1/2 in. Type X gypsum wallboard (may be attached
directly to joists or on resilient channels) or 5/8 in. Type X gypsum wallboard directly applied to joists.
5. 2x10 wood joists spaced 16 in. o.c.
Fire Tests: 1/2 in. Type X gypsum directly applied UL R1319-66, 11-9-64, Design L512; UL R3501-45, 5-27-65, Design L522; UL R2717-38, 6-10-65, Design L503; UL R3543-6, 11-10-65, Design L519; ULC Design M502 1/2 in. Type X gypsum on resilient channels UL R1319-65, 11-16-64, Design L514 5/8 in. Type X Gypsum directly applied UL R3501-5, 9, 7-15-52; UL R1319-2, 3, 6-5-52, Design L 501; ULC Design M500
Figure M16.1-10 One-Hour Fire-Resistive Wood Floor/Ceiling Assembly (2x10 Wood Joists 16" o.c. – Gypsum Directly Applied or on Optional Resilient Channels)
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1. Nominal 19/32 in. T&G plywood underlayment (single -
ted for certain designs. 2. Building paper. 3. -
signs may be nom. 7/16 in. OSB. 4. 2x10 wood joists spaced 16 in. o.c. 5. T-bar grid ceiling system. 6. Main runners spaced 48 in. o.c. 7. Cross-tees spaced 24 in. o.c. 8. 1/2 in. x 24 in. x 48 in. mineral acoustical ceiling panels
installed with holddown clips.
Figure M16.1-11 One-Hour Fire-Resistive Wood Floor/Ceiling Assembly (2x10 Wood Joists 16" o.c. – Suspended Acoustical Ceiling Panels)
Fire Tests: UL L209
AMERICAN WOOD COUNCIL
116 M16: FIRE DESIGN
1. 1-1/2 in. lightweight concrete or minimum 3/4 in.
paper may be optional and is not shown. 2.
designs may be nominal 7/16 in. OSB) or nominal
Oriented strand board (OSB) panels are permitted for certain designs.
3. 2x10 wood joists spaced 16 in. o.c. 4. 5/8 in. Type X Gypsum Wallboard or 1/2 in. propri-
etary Type X Gypsum Wallboard ceiling attached to resilient channels.
Figure M16.1-12 One-Hour Fire-Resistive Wood Floor/Ceiling Assembly (2x10 Wood Joists 16" o.c. – Gypsum on Resilient Channels)
Fire Tests: UL R1319-65, 11-16-64, Design L514 5/8 in. Type X
gypsum UL R6352, 4-21-71, Design L502 1/2 in. proprietary
Type X gypsum
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Figure M16.1-13 One-Hour Fire-Resistive Wood Floor/Ceiling Assembly (2x10 Wood Joists 24" o.c. – Gypsum on Resilient Channels)
1. 1-1/2 in. lightweight concrete or minimum 3/4 in.
2. Building paper (may be optional). 3. Nominal 23/32 in. T&G plywood or Oriented strand
4. 2x10 wood joists spaced 24 in. o.c. 5. Resilient channels. 6. 5/8 in. Type X Gypsum Wallboard ceiling.
Fire Tests: UL R5229-2, 5-25-73, Design L513
4
3
5
6
1, 2 not shown
AMERICAN WOOD COUNCIL
118 M16: FIRE DESIGN
Figure M16.1-14 Two-Hour Fire-Resistive Wood Floor/Ceiling Assembly (2x10 Wood Joists 16" o.c. – Gypsum Directly Applied with Second Layer on Resilient
Channels)
1. -
board (OSB) panels are permitted for certain de- signs.
2. Building paper. 3. Nominal 1x6 T&G boards or 15/32 in. plywood sub-
7/16 in. OSB. 4. 5/8 in. proprietary Type X Gypsum Wallboard ceiling
attached directly to joists. 5. 2x10 wood joists space 16 in. o.c. 6. Resilient channels. 7. 5/8 in. proprietary Type X Gypsum Wallboard ceiling
attached to resilient channels.
Fire Tests: UL R1319-114, 7-21-67, Design L511 UL R2717-35, 10-21-64, Design L505; ULC Design
M503
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Structural Glued Laminated Timber
Fires do not normally start in structural framing, but
laminated timber members perform very well under these conditions. Unprotected steel members typically suffer
catastrophically.
outer 3/4 in. of the structural glued laminated timber will be damaged. Char insulates a wood member and hence raises the temperature it can withstand. Most of the cross section will remain intact, and the member will continue
It is important to note that neither building materi- als alone, nor building features alone, nor detection and
- tories. The model building codes classify Heavy Timber
The requirements set out for Heavy Timber construc-
resistance. However, procedures are available to calculate the structural glued laminated timber size required for
NDS 16.2 and AF&PA’s Technical Report 10 available at www.awc.org). The minimum depths for selected struc- tural glued laminated timber sizes that can be adopted for
glued laminated timber beams. -
sions qualify them for this rating, the basic layup must be
center and the tension face augmented with the addition of a tension lamination. For more information concerning the
APA EWS Technical Note Y245 or AITC Technical Note
NDS 16.2 and AF&PA’s Technical Report 10 available at www.awc.org.
Table M16.1-6 Minimum Depths at Which Selected Beam Sizes Can Be Adopted for One-Hour Fire Ratings1
Beam Width (in.) 3 Sides Exposed 4 Sides Exposed 6-3/4 13-1/2 or 13-3/4 27 or 27-1/2 8-1/2 7-1/2 or 8-1/4 15 or 15-1/8 8-3/4 6-7/8 or 7-1/2 13-1/2 or 13-3/4 10-1/2 6 or 6-7/8 12 or 12-3/8 10-3/4 6 or 6-7/8 12 or 12-3/8
1. Assuming a load factor of 1.0 (design loads are equal to the capacity of the member). The minimum depths may be reduced when the design loads are less than the member capacity.
AMERICAN WOOD COUNCIL
120 M16: FIRE DESIGN
Very few elements of modern structures can be called
members are noncombustible, most of the furnishings are
in modern building codes addresses issues related to
materials combustible and noncombustible. While this topic is fairly complex for other types of
for poles and piles. Poles are generally used in cross- sectional sizes that qualify as heavy timber construction in the model building codes. On this basis, timber poles compare favorably with other construction materials in
-
substantially above the groundline.
Poles and Piles
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Heavy timber construction has proven to be accept-
These applications have proven to be not only reliable, but economical in certain structures – many wider width SCL products can be used in heavy timber construction. Consult manufacturer’s literature or code evaluation reports for
- hanced in the same ways as that of structures of steel, concrete, or masonry:
Fire sprinkler systems have proven to be effective in a variety of structures, both large and small
Protection of the structural members with materials such as properly attached gypsum sheathing can
in ASTM E-119, of up to 2 hours can be achieved through the use of gypsum sheathing
Where surface burning characteristics are critical,
To reiterate, this Manual does not purport to address this topic in an all-inclusive manner – it is merely an
- formance issues in the design of the structure.
Structural Composite Lumber
- teristics very similar to conventional wood frame members. Since many engineered wood products are proprietary, they are usually recognized in a code evaluation report published by an evaluation service. Each evaluation report
Very few elements of modern structures can be called
members are noncombustible, most of the furnishings are
model building codes addresses issues related to contain-
combustible and noncombustible. The primary intent of the building codes is to ensure structural stability to allow
As with the previous topic of durability, this Manual cannot cover the topic of designing for optimal structural
excellent texts on the topic, and designers are advised to use this information early in the design process. To assist
performance can be addressed, the following overview is provided.
Fire sprinklers are probably the most effective method
well as other systems). They are designed to control the
AMERICAN WOOD COUNCIL
122 M16: FIRE DESIGN
Wood I-Joists The wood I-joist industry has actively supported the
using wood I-joist products:
- tance ratings for generic I-joist systems. Detailed descriptions of these systems are shown in Figures M16.1-15 through M16.1-21 and are summarized in Table M16.1-7. In addition, sound transmission class (STC) and impact insulation class (IIC) ratings for each of these assemblies are provided. Updates to this information will be posted on the American Wood Council’s website at www.awc.org.
- tance ratings for proprietary I-joist systems. Detailed descriptions of these systems are available from the individual I-joist manufacturer.
• National Fire Protection Research Foundation Report titled “National Engineered Lightweight Construction Fire Research Project.” This report
performance of engineered lightweight construc- tion.
• A video, I-JOISTS:FACTS ABOUT PROGRESS, has been produced by the Wood I-Joist Manufacturer’s Association (WIJMA). This video describes some basic facts about changes taking place within the
with this video is a document that provides greater
I-joist systems.
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Table M16.1-7 Fire-Resistive Wood I-Joist Floor/Ceiling Assemblies
One-Hour Assemblies Joists Insulation Furring Ceiling Sheathing Fasteners Details I-joists @ 24" o.c.
Min. web thickness: 3/8" Min. I-joist depth: 9-1/4"
1-1/2" mineral wool batts (2.5 pcf - nominal) Resting on hat-shaped channels
Hat-shaped channels F
5/8" Type C Gypsum Wallboard
1-1/8" Type S drywall screws @ 12" o.c. (see fastening details)
Figure M16.1-15
I-joists @ 24" o.c.
Min. web thickness: 7/16" Min. I-joist depth: 9-1/4"
1-1/2" mineral wool batts (2.5 pcf - nominal) Resting on resilient channels
Resilient channels F
5/8" Type C Gypsum Wallboard
1" Type S drywall screws @ 8" o.c. (see fastening details)
Figure M16.1-16
I-joists @ 24" o.c.
Min. web thickness: 3/8" Min. I-joist depth: 9-1/4"
2" mineral wool batts (3.5 pcf - nominal) Resting on 1x4 setting strips
Resilient channels F
5/8" Type C Gypsum Wallboard
1-1/8" Type S drywall screws @ 7" o.c. (see fastening details)
Figure M16.1-17
I-joists @ 24" o.c.
Min. web thickness: 3/8" Min. I-joist depth: 9-1/4"
1" mineral wool batts (6 pcf - nominal) Resting on hat-shaped channels under I-joist bottom
Hat-shaped channels supported by CSC clips
F 1/2" Type C Gypsum Wallboard 1" Type S drywall screws @ 12" o.c. (see fastening details)
Figure M16.1-18
I-joists @ 24" o.c.
Min. web thickness: 3/8" Min. I-joist depth: 9-1/4"
(none) (none)
B 1/2" Type X Gypsum Wallboard 1-5/8" Type S drywall screws @ 12" o.c. Figure M16.1-19
F 1/2" Type X Gypsum Wallboard
2" Type S drywall screws @ 12" o.c. 1-1/2" Type G drywall screws @ 8" o.c. (see fastening details)
I-joists @ 24" o.c.
Min. web thickness: 3/8" Min. I-joist depth: 9-1/2"
(optional) Resilient channels
B 1/2" Type X Gypsum Wallboard 1-1/4" Type S drywall screws @ 12" o.c. Figure M16.1-20
F 1/2" Type X Gypsum Wallboard
1-5/8" Type S drywall screws @ 12" o.c. 1-1/2" Type G drywall screws @ 8" o.c. (see fastening details)
Two-Hour Assembly Joists Insulation Furring Ceiling Sheathing Fasteners Details I-joists @ 24" o.c.
Min. web thickness: 3/8" Min. I-joist depth: 9-1/4"
insulation supported by stay wires spaced 12" o.c.
(none) B 5/8" Type C Gypsum Wallboard 1-5/8" Type S drywall screws @ 12" o.c.
Figure M16.1-21Hat-shaped
channels
M 5/8" Type C Gypsum Wallboard 1" Type S drywall screws @ 12" o.c.
F 5/8" Type C Gypsum Wallboard 1-5/8" Type S drywall screws @ 8" o.c. (see fastening details)
B- Base layer sheathing (direct attached) M- Middle layer sheathing F- Face layer sheathing
AMERICAN WOOD COUNCIL
124 M16: FIRE DESIGN
1. Floor Topping (optional, not shown): Gypsum concrete, lightweight or normal concrete topping. 2. Floor Sheathing: Minimum 23/32-inch-thick tongue-and-groove wood sheathing (Exposure 1). Installed per code
3. Insulation: - nels.
4. Structural Members: 2
Types of Adhesives Used in Tested I-Joists Flange-to-Flange Endjoint Flange-to-Web Joint Web-to-Web Endjoint
5. Furring Channels:
6. Gypsum Wallboard:
7. Finish System (not shown): - ered with joint compound.
Figure M16.1-15 One-Hour Fire-Resistive Ceiling Assembly (WIJ-1.1) Floora/Ceiling - 100% Design Load - 1-Hour Rating - ASTM E 119/NFPA 251
STC and IIC Sound Ratings for Listed Assembly Without Gypsum Concrete With Gypsum Concrete
Cushioned Vinyl Carpet & Pad Cushioned Vinyl Carpet & Pad STC IIC STC IIC STC IIC STC IIC
- - - - - - a.
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1. Floor Topping (optional, not shown): Gypsum concrete, lightweight or normal concrete topping. 2. Floor Sheathing: Minimum 23/32-inch-thick tongue-and-groove wood sheathing (Exposure 1). Installed per code
3. Insulation: - nels.
4. Structural Members: 2
Types of Adhesives Used in Tested I-Joists Flange-to-Flange Endjoint Flange-to-Web Joint Web-to-Web Endjoint
5. Resilient Channels:
end joint extending to the next joist. 6. Gypsum Wallboard:
7. Finish System (not shown): - ered with joint compound.
Figure M16.1-16 One-Hour Fire-Resistive Ceiling Assembly (WIJ-1.2) Floora/Ceiling - 100% Design Load - 1 Hour Rating - ASTM E 119/NFPA 251
STC and IIC Sound Ratings for Listed Assembly Without Gypsum Concrete With Gypsum Concrete
Cushioned Vinyl Carpet & Pad Cushioned Vinyl Carpet & Pad STC IIC STC IIC STC IIC STC IIC
a.
AMERICAN WOOD COUNCIL
126 M16: FIRE DESIGN
1. Floor Topping (optional, not shown): Gypsum concrete, lightweight or normal concrete topping. 2. Floor Sheathing: Minimum 23/32-inch-thick tongue-and-groove wood sheathing (Exposure 1). Installed per code
requirements. 3. Insulation:
4. Structural Members: 2
Types of Adhesives Used in Tested I-Joists LVL Flange Adhesive Flange-to-Web Joint Web-to-Web Endjoint
Phenol-Resorcinol-Formaldehyde Emulsion Polymer Isocyanate Polyurethane Emulsion Polymer
5. Setting Strips:
6. Resilient Channels:
7. Gypsum Wallboard:
8. Finish System (not shown): -
Figure M16.1-17 One-Hour Fire-Resistive Ceiling Assembly (WIJ-1.3) Floora/Ceiling - 100% Design Load - 1-Hour Rating - ASTM E 119/NFPA 251
STC and IIC Sound Ratings for Listed Assembly Without Gypsum Concrete With Gypsum Concrete
Cushioned Vinyl Carpet & Pad Cushioned Vinyl Carpet & Pad STC IIC STC IIC STC IIC STC IIC
a.
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1. Floor Topping (optional, not shown): Gypsum concrete, lightweight or normal concrete topping. 2. Floor Sheathing: Minimum 23/32-inch-thick tongue-and-groove wood sheathing (Exposure 1). Installed per code
requirements with minimum 8d common nails. 3. Insulation:
4. Structural Members: 2
Types of Adhesives Used in Tested I-Joists Flange-to-Flange Endjoint Flange-to-Web Joint Web-to-Web Endjoint
5. Furring Channels:
6. Gypsum Wallboard:
-
7. Finish System (not shown): - ered with joint compound.
Figure M16.1-18 One-Hour Fire-Resistive Ceiling Assembly (WIJ-1.4) Floora/Ceiling - 100% Design Load - 1-Hour Rating - ASTM E 119/NFPA 251
STC and IIC Sound Ratings for Listed Assembly Without Gypsum Concrete With Gypsum Concrete
Cushioned Vinyl Carpet & Pad Cushioned Vinyl Carpet & Pad STC IIC STC IIC STC IIC STC IIC
- - a.
AMERICAN WOOD COUNCIL
128 M16: FIRE DESIGN
1. Floor Topping (optional, not shown): Gypsum concrete, lightweight or normal concrete topping. 2. Floor Sheathing: Minimum 23/32-inch-thick tongue-and-groove wood sheathing (Exposure 1). Installed per code
requirements with minimum 8d common nails. 3. Structural Members:
2
Types of Adhesives Used in Tested I-Joists LVL Flange Adhesive Flange-to-Web Joint Web-to-Web Endjoint
4. Gypsum Wallboard:
4a. Wallboard Base Layer:
4b. Wallboard Face Layer:
5. Finish System (not shown): - ered with joint compound.
Figure M16.1-19 One-Hour Fire-Resistive Ceiling Assembly (WIJ-1.5) Floora/Ceiling - 100% Design Load - 1-Hour Rating - ASTM E 119/NFPA 251
STC and IIC Sound Ratings for Listed Assembly Without Gypsum Concrete With Gypsum Concrete
Cushioned Vinyl Carpet & Pad Cushioned Vinyl Carpet & Pad STC IIC STC IIC STC IIC STC IIC
- - - - - - a.
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Figure M16.1-20 One-Hour Fire-Resistive Ceiling Assembly (WIJ-1.6) Floora/Ceiling - 100% Design Load - 1-Hour Rating - ASTM E 119/NFPA 251
1. Floor Topping (optional, not shown): Gypsum concrete, lightweight or normal concrete topping. 2. Floor Sheathing: Minimum 23/32-inch-thick tongue-and-groove wood sheathing (Exposure 1). Installed per code
3. Insulation (optional, not shown): 4. Structural Members:
2
Types of Adhesives Used in Tested I-Joists LVL Flange Adhesive Flange-to-Web Joint Web-to-Web Endjoint
Phenol-Resorcinol-Formaldehyde Emulsion Polymer Isocyanate Emulsion Polymer Isocyanate
5. Resilient Channelsb: -
6. Gypsum Wallboard:
6a. Wallboard Base Layer: screws at 12 inches on center.
6b. Wallboard Face Layer:
7. Finish System (not shown): -
STC and IIC Sound Ratings for Listed Assembly Without Gypsum Concrete With Gypsum Concrete
Cushioned Vinyl Carpet & Pad Cushioned Vinyl Carpet & Pad STC IIC STC IIC STC IIC STC IIC
With Insulation c c c c Without Insulation - - - - c c
a.
c.
AMERICAN WOOD COUNCIL
130 M16: FIRE DESIGN
Figure M16.1-21 Two-Hour Fire-Resistive Ceiling Assembly (WIJ-2.1) Floora/Ceiling - 100% Design Load - 2-Hour Rating - ASTM E119/NFPA 251
1. Floor Topping (optional, not shown): Gypsum concrete, lightweight or normal concrete topping. 2. Floor Sheathing: Minimum 23/32-inch-thick tongue-and-groove wood sheathing (Exposure 1). Installed per code
requirements. 3. Insulation:
spaced 12 inches on center. 4. Structural Members:
2
Types of Adhesives Used in Tested I-Joists LVL Flange Adhesive Flange-to-Web Joint Web-to-Web Endjoint
5. Furring Channels:
6. Gypsum Wallboard: 6a. Wallboard Base Layer:
-
6b. Wallboard Middle Layer:
6c. Wallboard Face Layer:
7. Finish System (not shown): - ered with joint compound.
STC and IIC Sound Ratings for Listed Assembly Without Gypsum Concrete With Gypsum Concrete
Cushioned Vinyl Carpet & Pad Cushioned Vinyl Carpet & Pad STC IIC STC IIC STC IIC STC IIC
- - a.
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Metal Plate Connected Wood Trusses -
dated by code for many of the applications where trusses could be used. All testing on these assemblies is performed in accordance with the ASTM’s Standard Methods for Fire Tests of Building Construction and Materials (ASTM E119).
assembly results are the Fire Resistance Design Manual, published by the Gypsum Association (GA) and the Fire Resistance Directory, published by Underwriters’ Labo- ratories, Inc. (UL). Warnock Hersey (WH) assemblies are now listed in the ITS Directory of Listed Products. These
- chitects or Building Designers, and for use by all Truss Manufacturers where a rated assembly is required, and
applications. According to the UL Directory’s Design Information
Section: “Ratings shown on individual designs apply to equal or greater height or thickness of the assembly, and to larger structural members, when both size and weight are
Thus, larger and deeper trusses can be used under the aus- pices of the same design number. This approach has often been used in roof truss applications since roof trusses are usually much deeper than the tested assemblies.
Thermal and/or acoustical considerations at times -
ing or roof-ceiling assembly that has been tested without insulation. As a general ‘rule,’ experience indicates that it is allowable to add insulation to an assembly, provided that the depth of the truss is increased by the depth of the insulation. And as a general ‘rule,’ assemblies that were tested with insulation may have the insulation removed.
to a tested assembly, one must look at the properties of the insulation and the impact that its placement inside the
of the assembly. Insulation retards the transfer of heat, is
and within an assembly. One potential effect of insulation placed directly on the gypsum board is to retard the dis- sipation of heat through the assembly, concentrating heat in the protective gypsum board.
- sistance of a professional engineer. This review is required
of the composite of the materials used in the construction of the assembly.
The following pages, courtesy of WTCA – Represent- ing the Structural Building Components Industry, include
and sound transmission ratings. For more information, visit www.sbcindustry.com. Also, several truss plate manufac-
For more detailed information on these assemblies, the individual truss plate manufacturer should be contacted.
- blies are available at their respective websites.
AMERICAN WOOD COUNCIL
132 M16: FIRE DESIGN
Roof and Floor Assemblies The following are only summaries. Users must consult
the listed testing agency’s documentation for complete information.
Certifying Agencies:
GA = Gypsum Association
NER = National Evaluation Service Report
PFS = PFS Corporation
UL = Underwriters Laboratory
WH = Warnock Hersey International, Ltd.
Note:
comparable products may be substituted.
45-Minute Fire Resistive Truss Designs: PFS 88-03, FR-SYSTEM 4
Fire Rating: 45 Minutes
Finish Rating: 22 Minutes
depth 15"
WH TSC/FCA 45-02
Fire Rating: 45 Minutes
Finish Rating: 22 Minutes
WH TSC/FCA 45-04
Fire Rating: 45 Minutes
Finish Rating: 22 Minutes
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One-Hour Fire Resistive Truss Designs:
GA – FC5406 & FC5408 RC2601 & RC2602 IBC Table 720.1(3)
Fire Rating: 1 Hr
GA – FC5512
Fire Rating: 1 Hr
GA – FC5515 or FC5516
Fire Rating: 1 Hr
GA – FC5517, PFS 86-10, or TPI/WTCA FC-392
Fire Rating: 1 Hr
NER – 392 WTCA – FR-SYSTEM 1™
Fire Rating: 1 Hr
16" depth
AMERICAN WOOD COUNCIL
134 M16: FIRE DESIGN
NER – 392 WTCA – FR-SYSTEM 3™
Fire Rating: 1 Hr
NER – 399
(see WTCA Metal Plate Connected Wood Truss Handbook for details – report discontinued)
Fire Rating: 1 Hr
PFS 89-58, FR-SYSTEM 5™
Fire Rating: 1 Hr
Finish Rating: 26 Minutes
UL – L528 & L534
Fire Rating: 1 Hr
Finish Rating: 22 Minutes
16" oc
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UL – L529
Fire Rating: 1 Hr
Finish Rating: 22 Minutes
UL – L542
Fire Rating: 1 Hr
UL – L546
insulation) Fire Rating: 1 Hr
Finish Rating: 25 Minutes
Resilient channel 16" oc or 12" oc
UL – L550, L521, L562, L563, L558, L574, and GA FC 5514
insulation) Fire Rating: 1 Hr
AMERICAN WOOD COUNCIL
136 M16: FIRE DESIGN
UL – P522 & P531, P533, P538, P544, P545, and GA RC2603 (pitched roof – duct or damper, optional insulation)
Fire Rating: 1 Hr
Finish Rating: 25 Minutes
Resilient channel 16" oc
WH TSC/FCA 60-02
Fire Rating: 1 Hr
Finish Rating: 22 Minutes
Resilient channel 24" oc
WH TSC/FCA 60-04
optional insulation) Fire Rating: 1 Hr
Finish Rating: 27 Minutes
WH TSC/FCA 60-06
Fire Rating: 1 Hr
Finish Rating: 24 Minutes
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WH TSC/FCA 60-08
optional insulation) Fire Rating: 1 Hr
WH TSC/FCA 60-10
Fire Rating: 1 Hr
Finish Rating: 45 Minutes
90-Minute Fire Resistive Truss Designs: WH TSC/FCA 90-02
Finish Rating: 45 Minutes
Two-Hour Fire Resistive Truss Designs: Calculated Assembly by Kirk Grundahl, P.E., Qualtim International, 1997
Fire Rating: 2 Hr
12" depth
Resilient channel 24" oc
AMERICAN WOOD COUNCIL
138 M16: FIRE DESIGN
NER – 392 WTCA – FR-SYSTEM 2™
Fire Rating: 2 Hr
Finish Rating: 65 Minutes
16" depth
channel added
PFS 89-71, FR-SYSTEM 6™
Fire Rating: 2 Hr
Resilient channel 16" oc
UL L-556, GA FC 5751, and RC 2751
Fire Rating: 2 Hr
Finish Rating: 2 Hr
Resilient channel 24" oc
UL L577
Fire Rating: 2 Hr
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Figure M16.1-22 Cross Sections of Possible One-Hour Area Separations
AMERICAN WOOD COUNCIL
140 M16: FIRE DESIGN
Area Separation Assemblies
- tural inadequacies could cause the assemblies to fail unexpectedly, increasing the risk of loss of life. There
endurance details that maintain 1-hour rated area separa- tion assemblies.
Figure M16.1-22 shows several possible assemblies that can be used to make up the 1-hour rated system for
- lel to the wall assembly; and b) perpendicular to the wall
the wall top plates. This effectively prevents the spread of
occurrence. The tenant separation in the roof is maintained through the use of a 1/2-inch gypsum wallboard draftstop attached to the ends of one side of the monopitch trusses and provided for the full truss height. Figure M16.1-22 effectively provides 1-hour compartmentation for all the occupied spaces using listed 1-hour rated assemblies and the appropriate draftstops for the concealed spaces as prescribed by the model building codes.
is required within concealed attic spaces, the details shown to the right (UL U338, U339, and U377) provide approved 1-hour and 2-hour rated assemblies that may be used within the roof cavity and that may be constructed with gable end frames.
include: • Ensuring that the wall and ceiling assemblies of
the room use 1-hour rated assemblies. These are independent assemblies. The wall assembly does
performance of the structure. The intent of the code is that the building be broken into compartments
assemblies are tested to provide code-complying
foregoing details meet the intent of the code. • Properly fastening the gypsum wallboard to the wall
studs and trusses. This is critical for achieving the -
bly.
• Ensuring that the detail being used is structurally sound, particularly the bearing details. All connec- tion details are critical to assembly performance.
the system will fail at the poor connection detail earlier than expected.
• Accommodating both sound structural details with -
tested, rational engineering judgment needs to be used.
The foregoing principles could also be applied to struc- tures requiring 2-hour rated area separation assemblies. In this case, acceptable 2-hour wall assemblies would be used
-
Through-Penetration Fire Stops
of plumbing, ventilation, electrical, and communication purposes, ASTM E814 Standard Method of Fire Tests of Through-Penetration Fire Stops assemblies (rated per ASTM E119) and penetrates them with cables, pipes, and ducts, etc., before subjecting the
- ceptable. Properties are measured according to the passage
expressed in hourly terms, in much the same fashion as
-
- velop any opening that would permit a projection of water from the stream beyond the unexposed side.
-
prevent the transmission of heat during the prescribed rating period which would increase the temperature of any thermocouple on its unexposed surface, or any penetrating
The UL Fire Resistance Directory lists literally thou- sands of tested systems. They have organized the systems
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UL – U338 (wall – bearing/non-bearing, optional insulation)
Fire Rating: 1 Hr
UL – U339 (wall – bearing/non-bearing, optional insulation)
Fire Rating: 1 Hr
UL – U377 (wall – bearing, required insulation)
Fire Rating: 2 Hr
side
Floor
AMERICAN WOOD COUNCIL
142 M16: FIRE DESIGN
-
-
- nation of penetrants.
Figure M16.1-23 Examples of Through-Penetration Firestop Systems
- lic pipe would have a designation of F-C-1xxx, or with nonmetallic pipe would be designated F-C-2xxx. A few
Examples in Figure M16.1-23 are from the UL Fire Resis- tance Directory, Vol. II: UL Systems F-C-2008, F-C-1006, F-C-3007 & 8, F-C-5002.
7003-C-F LU8002-C-F LU
UL F-C-1006 UL F-C-5002
Pipe or Conduit
Pipe or Conduit
UL F-C-3008
F-Rating - 1 Hr T-Rating - 1 Hr
F-Rating - 1 Hr T-Rating - 1 Hr
F-Rating - 1 Hr T-Rating - 1 Hr
Firestop system
Pipe or Conduit
General assembly
Firestop system
General assembly
General assembly
General assembly
General assembly
General assembly
Firestop system
Firestop system
F-Rating - 1 Hr T-Rating - 1 Hr
F-Rating - 1 Hr T-Rating - 1 Hr
Cables
Schedule 10 Steel or copper pipe with pipe covering
F-Rating - 1 Hr T-Rating - 1 Hr
Firestop systemFirestop
system
Firestop system
Cables
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STC Rating Privacy Afforded 25 Normal speech easily understood 30 Normal speech audible, but not intelligible 35 Loud speech audible and fairly understandable 40 Loud speech barely audible, but not intel-
ligible 45 Loud speech barely audible 50 Shouting barely audible 55 Shouting inaudible
Table M16.1-8 Privacy Afforded According to STC Rating
Description Frequency STC High
IIC Low
joist (I-joist, solid sawn, or truss) 3/4" decking and 5/8" gypsum wallboard di- rectly attached to ceiling
36 33
Cushioned vinyl or linoleum 0 2 Non-cushioned vinyl or linoleum 0 0
0 1 3/4" Gypcrete® or Elastizel® 7 to 8 1 1 1/2" lightweight concrete 7 to 8 1 1/2" sound deadening board (USG)1 1 5 Quiet-Cor® underlayment by Tarkett, Inc.1 1 8 Enkasonic® by American Enka Company1 4 13
® by Laminating Services, Inc.1 1 11 R-19 batt insulation 2 0 R-11 batt insulation 1 0 3" mineral wool insulation 1 0 Resilient channel 10 8 Resilient with insulation 13 15 Extra layer of 5/8" gypsum wallboard 0 to 2 2 to 4 Carpet & pad 0 20 to 25 1. Estimates based on proprietary literature. Verify with individual
companies.
Table M16.1-9 Contributions of Various Products to STC or IIC Rating
Transitory Floor Vibration and Sound Transmission Sound Transmission
Sound transmission ratings are closely aligned with
of least resistance. Sound striking a wall or ceiling surface is transmit-
ted through the air in the wall or ceiling cavity. It then strikes the opposite wall surface, causing it to vibrate and transmit the sound into the adjoining room. Sound also is transmitted through any openings into the room, such as air ducts, electrical outlets, window openings, and doors. This is airborne sound transmission. The Sound Trans- mission Class (STC) method of rating airborne sounds evaluates the comfort ability of a particular living space. The higher the STC, the better the airborne noise control performance of the structure. An STC of 50 or above is generally considered a good airborne noise control rating. Table M16.1-6 describes the privacy afforded according to the STC rating.
Impact Sound Transmission is produced when a structural element is set into vibration by direct impact – someone walking, for example. The vibrating surface generates sound waves on both sides of the element. The Impact Insulation Class (IIC) is a method of rating the impact sound transmission performance of an assembly. The higher the IIC, the better the impact noise control of the element. An IIC of 55 is generally considered a good impact noise control.
Estimated Wood Floor Sound Performance1,2,3 Sound transmission and impact insulation character-
individual components. The contributions of various prod- ucts to an STC or IIC rating are shown in Table M16.1-9. An example calculation is shown in Table M16.1-10.
Tables M16.1-11 and M16.1-12 provide STC and IIC -
nected wood truss assemblies. Ratings are provided for
and pad, vinyl, lightweight concrete, and gypcrete.
1. Acoustical Manual, National Association of Home Builders, 1978. 2. Yerges, Lyle F., Sound, Noise and Vibration Control, 1969. 3. Catalog of STC and IIC Ratings for Wall and Floor/Ceiling Assemblies,
AMERICAN WOOD COUNCIL
144 M16: FIRE DESIGN
Table M16.1-11 STC & IIC Ratings for UL L528/L529
Table M16.1-12 STC & IIC Ratings for FC-214
Description of Materials: Gypcrete 3/4"
Lightweight Concrete 1"
Carpet 2.63 Kg/M2
Pad 1.37 Kg/M2
Tables used with permission of Truss Plate Institute, Inc.
* Does not match source document which was in error.
Floor Covering STC IIC Test Number Carpet & Pad 48 56 NRC 1039 & 1040 Vinyl 45 37 NRC 1041 & 1042 Lightweight, Carpet & Pad 57 72 NRC 1044 & 1045 Lightweight and Vinyl 57 50* NRC 1047 & 1048 Gypcrete & Cushioned Vinyl -- 53 6-442-2 Gypcrete Gypcrete, Carpet & Pad -- 74 6-442-3 Gypcrete Gypcrete 58 -- 6-442-5 Gypcrete
Floor Covering STC IIC Test Number Carpet & Pad 48 54 NRC 1059 & 1060 Vinyl 47 35 NRC 1063 & 1064 Lightweight, Carpet & Pad 56 72 NRC 1053 & 1054 Lightweight and Vinyl 56 48 NRC 1051 & 1052 Gypcrete, Carpet & Pad 52 63 NRC 1076 & 1077 Gypcrete 53 43 NRC 1085 & 1086
Description STC IIC Carpet & pad 0 20 3/4" Gypcrete 7 1
36 33 Resilient channel 10 8 Total 53 62
Table M16.1-10 Example Calculation
AMERICAN FOREST & PAPER ASSOCIATION
145ASD/LRFD MANUAL FOR ENGINEERED WOOD CONSTRUCTION M
1 6 : FIR
E D ES
IG N
16
M16.2 Design Procedures for Exposed Wood Members
For members stressed in one principle direction, sim-
be used to determine the structural design load ratio, Rs, at
endurance time. This section provides the rational used to develop the load ratio tables provided later in this section (Tables M16.2-1 through M16.2-10). For more complex calculations where stress interactions must be considered, use the provisions of AF&PA’s Technical Report 10 with the appropriate NDS provisions.
Bending Members (Tables M16.2-1 through M16.2-2)
Structural: D+L Rs Fb Ss CL-s CD CM Ct
Fire: D+L 2.85 Fb Sf CL-f
where: D = Design dead load
L = Design live load
Rs = Design load ratio
Fb = Tabulated bending design value
Ss = Section modulus using full cross- section dimensions
Sf = Section modulus using cross-section dimensions reduced from fire exposure
CL-s = Beam stability factor using full cross- section dimensions
CL-f = Beam stability factor using cross- section dimensions reduced from fire exposure
CD = Load duration factor
CM = Wet service factor
Ct = Temperature factor
Solve for Rs:
s f L- f
s L-s D M t R =
2.85 S C S C C C C (M16.2-1)
Load ratio tables were developed for standard refer- ence conditions where: CD = 1.0; CM = 1.0; Ct = 1.0; CL-f = 1.0
The calculation of CL-s and CL-f require the designer to consider both the change in bending section relative to bending strength and the change in buckling stiffness relative to buckling strength. While these relationships can be directly calculated using NDS provisions, they can not be easily tabulated. However, for most beams exposed on three sides, the beams are braced on the protected side. For long span beams exposed on four sides, the beam
When buckling is considered, the following equations should be used:
Structural (buckling): D+L Rs Emin Iyy-s / e CM Ct
Fire (buckling): D+L 2.03 Emin Iyy-f / e
where: D = Design dead load
L = Design live load
Rs = Design load ratio (buckling)
Emin = Reference modulus of elasticity for beam stability calculations
Iyy-s = Lateral moment of inertia using full cross-section dimensions
Iyy-f = Lateral moment of inertia using cross-section dimensions reduced from fire exposure
CM = Wet service factor
Ct = Temperature factor
s yy- f
yy-s M t R =
2.03 I I C C
(M16.2-2)
AMERICAN WOOD COUNCIL
146 M16: FIRE DESIGN
Compression Members (Tables M16.2-3 through M16.2-5)
Structural: D+L Rs Fc Cp-s CD CM Ct
Fire: D+L 2.58 Fc Cp-f
where: D = Design dead load
L = Design live load
Rs = Design load ratio
Fc = Tabulated compression parallel-to- grain design value
Cp-s = Column stability factor using full cross-section dimensions
Cp-f = Column stability factor using cross- section dimensions reduced from fire exposure
CD = Load duration factor
CM = Wet service factor
Ct = Temperature factor
The calculation of Cp-s and Cp-f require the designer to consider both the change in compression area relative to compression parallel-to-grain strength and the change in buckling stiffness relative to buckling strength. While these relationships can be directly calculated using NDS provisions, they can not be easily tabulated. However, for
reason, conservative load ratio tables can be tabulated
exposure.
Structural (buckling): D+L Rs 2 Emin Is / e
2 CM Ct
Fire (buckling): D+L 2.03 2 Emin If / e 2
where: D = Design dead load
L = Design live load
Rs = Design load ratio (buckling)
Emin = Reference modulus of elasticity for column stability calculations
Is = Moment of inertia using full cross- section dimensions
If = Moment of inertia using cross- section dimensions reduced from fire exposure
CM = Wet service factor
Ct = Temperature factor
s f
s M t R =
2.03 I I C C (M16.2-3)
Buckling load ratio tables were developed for standard reference conditions where: CM = 1.0; Ct = 1.0
NOTE: The load duration factor, CD, is not in- cluded in the load ratio tables since modulus of elasticity values, E, used in the buckling capacity calculation is not adjusted for load duration in the NDS.
Tension Members (Tables M16.2-6 through M16.2-8)
Structural: D+L Rs Ft As CD CM Ct Ci
Fire: D+L 2.85 Ft Af
where: D = Design dead load
L = Design live load
Rs = Design load ratio
Ft = Tabulated tension parallel-to-grain design value
As = Area of cross section using full cross- section dimensions
Af = Area of cross section using cross- section dimensions reduced from fire exposure
CD = Load duration factor
CM = Wet service factor
Ct = Temperature factor
s f
s D M t R =
2.85 A A C C C
(M16.2-4)
Load ratio tables were developed for standard refer- ence conditions where: CD = 1.0; CM = 1.0; Ct = 1.0
AMERICAN FOREST & PAPER ASSOCIATION
147ASD/LRFD MANUAL FOR ENGINEERED WOOD CONSTRUCTION M
1 6 : FIR
E D ES
IG N
16
Table M16.2-1 Design Load Ratios for Bending Members Exposed on Three Sides (Structural Calculations at Standard Reference Conditions: CD = 1.0, CM = 1.0, Ct = 1.0, Ci = 1.0, CL = 1.0)
(Protected Surface in Depth Direction)
Note: Tabulated values assume bending in the depth direction.
Table M16.2-1A Southern Pine Structural Glued Laminated Timbers
Table M16.2-1B Western Species Structural Glued Laminated Timbers
Rating 1-HOUR 1.5-HOUR 2-HOUR Rating 1-HOUR 1.5-HOUR 2-HOUR Beam Width 5 6.75 8.5 10.5 6.75 8.5 10.5 8.5 10.5 Beam Width 5.125 6.75 8.75 10.75 6.75 8.75 10.75 8.75 10.75 Beam Depth Design Load Ratio, Rs Beam Depth Design Load Ratio, Rs
5.5 0.36 0.60 0.74 0.85 0.22 0.35 0.44 0.13 0.20 6 0.42 0.65 0.82 0.93 0.25 0.41 0.52 0.18 0.26 6.875 0.43 0.72 0.90 1.00 0.30 0.47 0.60 0.21 0.33 7.5 0.49 0.77 0.97 1.00 0.33 0.54 0.68 0.26 0.39 8.25 0.49 0.81 1.00 1.00 0.36 0.57 0.72 0.28 0.43 9 0.54 0.85 1.00 1.00 0.38 0.64 0.79 0.33 0.49
9.625 0.53 0.88 1.00 1.00 0.40 0.64 0.82 0.33 0.51 10.5 0.58 0.91 1.00 1.00 0.43 0.71 0.88 0.39 0.57 11 0.56 0.93 1.00 1.00 0.44 0.70 0.89 0.37 0.58 12 0.61 0.96 1.00 1.00 0.46 0.76 0.95 0.43 0.64
12.375 0.58 0.97 1.00 1.00 0.47 0.75 0.95 0.40 0.63 13.5 0.64 1.00 1.00 1.00 0.49 0.81 1.00 0.46 0.69 13.75 0.60 1.00 1.00 1.00 0.49 0.78 1.00 0.43 0.67 15 0.66 1.00 1.00 1.00 0.51 0.85 1.00 0.49 0.73
15.125 0.62 1.00 1.00 1.00 0.51 0.82 1.00 0.46 0.71 16.5 0.67 1.00 1.00 1.00 0.53 0.88 1.00 0.52 0.77 16.5 0.63 1.00 1.00 1.00 0.53 0.84 1.00 0.48 0.74 18 0.69 1.00 1.00 1.00 0.55 0.90 1.00 0.54 0.80
17.875 0.65 1.00 1.00 1.00 0.54 0.87 1.00 0.49 0.77 19.5 0.70 1.00 1.00 1.00 0.56 0.93 1.00 0.55 0.82 19.25 0.66 1.00 1.00 1.00 0.56 0.89 1.00 0.51 0.79 21 0.71 1.00 1.00 1.00 0.57 0.95 1.00 0.57 0.85
20.625 0.66 1.00 1.00 1.00 0.57 0.90 1.00 0.52 0.81 22.5 0.72 1.00 1.00 1.00 0.58 0.96 1.00 0.58 0.87 22 0.67 1.00 1.00 1.00 0.58 0.92 1.00 0.53 0.83 24 0.73 1.00 1.00 1.00 0.59 0.98 1.00 0.60 0.88
23.375 0.68 1.00 1.00 1.00 0.59 0.93 1.00 0.55 0.85 25.5 0.73 1.00 1.00 1.00 0.60 0.99 1.00 0.61 0.90 24.75 0.69 1.00 1.00 1.00 0.60 0.95 1.00 0.55 0.86 27 0.74 1.00 1.00 1.00 0.61 1.00 1.00 0.62 0.91
26.125 0.69 1.00 1.00 1.00 0.60 0.96 1.00 0.56 0.88 28.5 0.74 1.00 1.00 1.00 0.61 1.00 1.00 0.62 0.93 27.5 0.70 1.00 1.00 1.00 0.61 0.97 1.00 0.57 0.89 30 0.75 1.00 1.00 1.00 0.62 1.00 1.00 0.63 0.94
28.875 0.70 1.00 1.00 1.00 0.61 0.98 1.00 0.58 0.90 31.5 0.75 1.00 1.00 1.00 0.62 1.00 1.00 0.64 0.95 30.25 0.71 1.00 1.00 1.00 0.62 0.99 1.00 0.58 0.91 33 0.76 1.00 1.00 1.00 0.63 1.00 1.00 0.65 0.96
31.625 0.71 1.00 1.00 1.00 0.62 0.99 1.00 0.59 0.92 34.5 0.76 1.00 1.00 1.00 0.63 1.00 1.00 0.65 0.97 33 0.71 1.00 1.00 1.00 0.63 1.00 1.00 0.60 0.93 36 0.77 1.00 1.00 1.00 0.64 1.00 1.00 0.66 0.98
34.375 0.72 1.00 1.00 1.00 0.63 1.00 1.00 0.60 0.93 37.5 1.00 1.00 1.00 0.64 1.00 1.00 0.66 0.98 35.75 0.72 1.00 1.00 1.00 0.64 1.00 1.00 0.61 0.94 39 1.00 1.00 1.00 0.64 1.00 1.00 0.67 0.99
37.125 1.00 1.00 1.00 0.64 1.00 1.00 0.61 0.95 40.5 1.00 1.00 1.00 0.65 1.00 1.00 0.67 1.00 38.5 1.00 1.00 1.00 0.64 1.00 1.00 0.61 0.95 42 1.00 1.00 1.00 0.65 1.00 1.00 0.68 1.00
39.875 1.00 1.00 1.00 0.65 1.00 1.00 0.62 0.96 43.5 1.00 1.00 1.00 0.65 1.00 1.00 0.68 1.00 41.25 1.00 1.00 1.00 0.65 1.00 1.00 0.62 0.97 45 1.00 1.00 1.00 0.66 1.00 1.00 0.68 1.00
42.625 1.00 1.00 1.00 0.65 1.00 1.00 0.63 0.97 46.5 1.00 1.00 1.00 0.66 1.00 1.00 0.69 1.00 44 1.00 1.00 1.00 0.66 1.00 1.00 0.63 0.98 48 1.00 1.00 1.00 0.66 1.00 1.00 0.69 1.00
45.375 1.00 1.00 1.00 0.66 1.00 1.00 0.63 0.98 49.5 1.00 1.00 1.00 1.00 0.69 1.00 46.75 1.00 1.00 1.00 0.66 1.00 1.00 0.63 0.99 51 1.00 1.00 1.00 1.00 0.70 1.00
48.125 1.00 1.00 1.00 0.66 1.00 1.00 0.64 0.99 52.5 1.00 1.00 1.00 1.00 0.70 1.00 49.5 1.00 1.00 1.00 1.00 0.64 0.99 54 1.00 1.00 1.00 1.00 0.70 1.00
50.875 1.00 1.00 1.00 1.00 0.64 1.00 55.5 1.00 1.00 1.00 1.00 0.70 1.00 52.25 1.00 1.00 1.00 1.00 0.64 1.00 57 1.00 1.00 1.00 1.00 0.70 1.00
53.625 1.00 1.00 1.00 1.00 0.65 1.00 58.5 1.00 1.00 1.00 1.00 0.71 1.00 55 1.00 1.00 1.00 1.00 0.65 1.00 60 1.00 1.00 1.00 1.00 0.71 1.00
56.375 1.00 1.00 1.00 1.00 0.65 1.00 61.5 1.00 1.00 1.00 1.00 0.71 1.00 57.75 1.00 1.00 1.00 1.00 0.65 1.00 63 1.00 1.00 1.00 1.00 0.71 1.00
59.125 1.00 1.00 1.00 1.00 0.65 1.00 64.5 1.00 1.00 1.00 60.5 1.00 1.00 1.00 1.00 0.66 1.00 66 1.00 1.00 1.00
61.875 1.00 1.00 1.00 1.00 0.66 1.00 67.5 1.00 1.00 1.00 63.25 1.00 1.00 1.00 1.00 0.66 1.00 69 1.00 1.00 1.00
64.625 1.00 1.00 1.00 70.5 1.00 1.00 1.00 66 1.00 1.00 1.00 72 1.00 1.00 1.00
67.375 1.00 1.00 1.00 73.5 1.00 1.00 1.00 68.75 1.00 1.00 1.00 75 1.00 1.00 1.00
70.125 1.00 1.00 1.00 76.5 1.00 1.00 1.00 71.5 1.00 1.00 1.00 78 1.00 1.00 1.00
72.875 1.00 1.00 1.00 79.5 1.00 1.00 1.00 74.25 1.00 1.00 1.00 81 1.00 1.00 1.00
75.625 1.00 1.00 1.00 77 1.00 1.00 1.00
Table M16.2-1C Solid Sawn Timbers Rating 1-HOUR 1.5-HOUR 2-HOUR
Beam Width 5.5 7.5 9.5 11.5 7.5 9.5 11.5 9.5 11.5 Beam Depth Design Load Ratio, Rs
5.5 0.45 0.67 0.80 0.89 0.28 0.40 0.48 0.17 0.23 7.5 0.57 0.86 1.00 1.00 0.42 0.60 0.71 0.32 0.43 9.5 0.65 0.97 1.00 1.00 0.51 0.73 0.87 0.42 0.57 11.5 0.70 1.00 1.00 1.00 0.58 0.83 0.99 0.50 0.67 13.5 0.74 1.00 1.00 1.00 0.63 0.89 1.00 0.56 0.75 15.5 0.77 1.00 1.00 1.00 0.67 0.95 1.00 0.60 0.81 17.5 0.79 1.00 1.00 1.00 0.70 0.99 1.00 0.64 0.86 19.5 0.81 1.00 1.00 1.00 0.72 1.00 1.00 0.67 0.90 21.5 0.83 1.00 1.00 1.00 0.74 1.00 1.00 0.69 0.93 23.5 0.84 1.00 1.00 1.00 0.76 1.00 1.00 0.71 0.96
AMERICAN WOOD COUNCIL
148 M16: FIRE DESIGN
Table M16.2-2 Design Load Ratios for Bending Members Exposed on Four Sides (Structural Calculations at Standard Reference Conditions: CD = 1.0, CM = 1.0, Ct = 1.0, Ci = 1.0, CL=1.0)
Note: Tabulated values assume bending in the depth direction.
Table M16.2-2A Southern Pine Structural Glued Laminated Timbers
Table M16.2-2B Western Species Structural Glued Laminated Timbers
Rating 1-HOUR 1.5-HOUR 2-HOUR Rating 1-HOUR 1.5-HOUR 2-HOUR Beam Width 5 6.75 8.5 10.5 6.75 8.5 10.5 8.5 10.5 Beam Width 5.125 6.75 8.75 10.75 6.75 8.75 10.75 8.75 10.75 Beam Depth Design Load Ratio, Rs Beam Depth Design Load Ratio, Rs
5.5 0.10 0.16 0.20 0.22 0.01 0.01 0.01 0.02 0.03 6 0.14 0.21 0.27 0.30 0.02 0.03 0.04 0.00 0.00 6.875 0.18 0.30 0.37 0.42 0.05 0.09 0.11 0.00 0.01 7.5 0.23 0.36 0.45 0.51 0.08 0.13 0.17 0.02 0.03 8.25 0.25 0.42 0.52 0.59 0.11 0.18 0.23 0.04 0.06 9 0.31 0.48 0.60 0.68 0.15 0.24 0.30 0.07 0.10
9.625 0.31 0.52 0.64 0.73 0.17 0.27 0.34 0.09 0.13 10.5 0.37 0.57 0.72 0.82 0.20 0.33 0.42 0.12 0.19 11 0.36 0.60 0.74 0.85 0.22 0.35 0.44 0.13 0.20 12 0.42 0.65 0.82 0.93 0.25 0.41 0.52 0.18 0.26
12.375 0.40 0.67 0.83 0.94 0.26 0.42 0.53 0.17 0.27 13.5 0.46 0.72 0.90 1.00 0.29 0.48 0.60 0.22 0.33 13.75 0.43 0.72 0.90 1.00 0.30 0.47 0.60 0.21 0.33 15 0.49 0.77 0.97 1.00 0.33 0.54 0.68 0.26 0.39
15.125 0.46 0.77 0.95 1.00 0.33 0.52 0.67 0.25 0.38 16.5 0.52 0.81 1.00 1.00 0.36 0.59 0.74 0.30 0.45 16.5 0.49 0.81 1.00 1.00 0.36 0.57 0.72 0.28 0.43 18 0.54 0.85 1.00 1.00 0.38 0.64 0.79 0.33 0.49
17.875 0.51 0.85 1.00 1.00 0.38 0.61 0.77 0.30 0.47 19.5 0.56 0.88 1.00 1.00 0.41 0.67 0.84 0.36 0.54 19.25 0.53 0.88 1.00 1.00 0.40 0.64 0.82 0.33 0.51 21 0.58 0.91 1.00 1.00 0.43 0.71 0.88 0.39 0.57
20.625 0.54 0.91 1.00 1.00 0.42 0.67 0.86 0.35 0.54 22.5 0.60 0.94 1.00 1.00 0.45 0.74 0.92 0.41 0.61 22 0.56 0.93 1.00 1.00 0.44 0.70 0.89 0.37 0.58 24 0.61 0.96 1.00 1.00 0.46 0.76 0.95 0.43 0.64
23.375 0.57 0.95 1.00 1.00 0.45 0.72 0.92 0.39 0.60 25.5 0.63 0.98 1.00 1.00 0.48 0.79 0.98 0.45 0.66 24.75 0.58 0.97 1.00 1.00 0.47 0.75 0.95 0.40 0.63 27 0.64 1.00 1.00 1.00 0.49 0.81 1.00 0.46 0.69
26.125 0.59 0.99 1.00 1.00 0.48 0.77 0.97 0.42 0.65 28.5 0.65 1.00 1.00 1.00 0.50 0.83 1.00 0.48 0.71 27.5 0.60 1.00 1.00 1.00 0.49 0.78 1.00 0.43 0.67 30 0.66 1.00 1.00 1.00 0.51 0.85 1.00 0.49 0.73
28.875 0.61 1.00 1.00 1.00 0.50 0.80 1.00 0.44 0.69 31.5 0.67 1.00 1.00 1.00 0.52 0.86 1.00 0.50 0.75 30.25 0.62 1.00 1.00 1.00 0.51 0.82 1.00 0.46 0.71 33 0.67 1.00 1.00 1.00 0.53 0.88 1.00 0.52 0.77
31.625 0.63 1.00 1.00 1.00 0.52 0.83 1.00 0.47 0.73 34.5 0.68 1.00 1.00 1.00 0.54 0.89 1.00 0.53 0.78 33 0.63 1.00 1.00 1.00 0.53 0.84 1.00 0.48 0.74 36 0.69 1.00 1.00 1.00 0.55 0.90 1.00 0.54 0.80
34.375 0.64 1.00 1.00 1.00 0.54 0.86 1.00 0.49 0.75 37.5 1.00 1.00 1.00 0.55 0.92 1.00 0.55 0.81 35.75 0.65 1.00 1.00 1.00 0.54 0.87 1.00 0.49 0.77 39 1.00 1.00 1.00 0.56 0.93 1.00 0.55 0.82
37.125 1.00 1.00 1.00 0.55 0.88 1.00 0.50 0.78 40.5 1.00 1.00 1.00 0.57 0.94 1.00 0.56 0.84 38.5 1.00 1.00 1.00 0.56 0.89 1.00 0.51 0.79 42 1.00 1.00 1.00 0.57 0.95 1.00 0.57 0.85
39.875 1.00 1.00 1.00 0.56 0.90 1.00 0.52 0.80 43.5 1.00 1.00 1.00 0.58 0.96 1.00 0.58 0.86 41.25 1.00 1.00 1.00 0.57 0.90 1.00 0.52 0.81 45 1.00 1.00 1.00 0.58 0.96 1.00 0.58 0.87
42.625 1.00 1.00 1.00 0.57 0.91 1.00 0.53 0.82 46.5 1.00 1.00 1.00 0.59 0.97 1.00 0.59 0.88 44 1.00 1.00 1.00 0.58 0.92 1.00 0.53 0.83 48 1.00 1.00 1.00 0.59 0.98 1.00 0.60 0.88
45.375 1.00 1.00 1.00 0.58 0.93 1.00 0.54 0.84 49.5 1.00 1.00 0.99 1.00 0.60 0.89 46.75 1.00 1.00 1.00 0.59 0.93 1.00 0.55 0.85 51 1.00 1.00 0.99 1.00 0.61 0.90
48.125 1.00 1.00 1.00 0.59 0.94 1.00 0.55 0.85 52.5 1.00 1.00 1.00 1.00 0.61 0.91 49.5 1.00 1.00 0.95 1.00 0.55 0.86 54 1.00 1.00 1.00 1.00 0.62 0.91
50.875 1.00 1.00 0.95 1.00 0.56 0.87 55.5 1.00 1.00 1.00 1.00 0.62 0.92 52.25 1.00 1.00 0.96 1.00 0.56 0.88 57 1.00 1.00 1.00 1.00 0.62 0.93
53.625 1.00 1.00 0.96 1.00 0.57 0.88 58.5 1.00 1.00 1.00 1.00 0.63 0.93 55 1.00 1.00 0.97 1.00 0.57 0.89 60 1.00 1.00 1.00 1.00 0.63 0.94
56.375 1.00 1.00 0.97 1.00 0.57 0.89 61.5 1.00 1.00 1.00 1.00 0.64 0.94 57.75 1.00 1.00 0.98 1.00 0.58 0.90 63 1.00 1.00 1.00 1.00 0.64 0.95
59.125 1.00 1.00 0.98 1.00 0.58 0.90 64.5 1.00 1.00 0.95 60.5 1.00 1.00 0.99 1.00 0.58 0.91 66 1.00 1.00 0.96
61.875 1.00 1.00 0.99 1.00 0.59 0.91 67.5 1.00 1.00 0.96 63.25 1.00 1.00 0.99 1.00 0.59 0.92 69 1.00 1.00 0.97
64.625 1.00 1.00 0.92 70.5 1.00 1.00 0.97 66 1.00 1.00 0.93 72 1.00 1.00 0.98
67.375 1.00 1.00 0.93 73.5 1.00 1.00 0.98 68.75 1.00 1.00 0.93 75 1.00 1.00 0.98
70.125 1.00 1.00 0.94 76.5 1.00 1.00 0.99 71.5 1.00 1.00 0.94 78 1.00 1.00 0.99
72.875 1.00 1.00 0.95 79.5 1.00 1.00 0.99 74.25 1.00 1.00 0.95 81 1.00 1.00 1.00
75.625 1.00 1.00 0.95 77 1.00 1.00 0.95
Table M16.2-2C Solid Sawn Timbers Rating 1-HOUR 1.5-HOUR 2-HOUR
Beam Width 5.5 7.5 9.5 11.5 7.5 9.5 11.5 9.5 11.5 Beam Depth Design Load Ratio, Rs
5.5 0.12 0.18 0.21 0.23 0.01 0.01 0.01 0.02 0.03 7.5 0.27 0.40 0.48 0.53 0.10 0.15 0.18 0.02 0.03 9.5 0.38 0.57 0.68 0.76 0.21 0.30 0.36 0.11 0.14 11.5 0.46 0.70 0.84 0.92 0.30 0.43 0.51 0.19 0.26 13.5 0.53 0.80 0.95 1.00 0.38 0.53 0.64 0.27 0.36 15.5 0.58 0.87 1.00 1.00 0.43 0.62 0.74 0.33 0.45 17.5 0.62 0.93 1.00 1.00 0.48 0.69 0.82 0.39 0.52 19.5 0.65 0.99 1.00 1.00 0.52 0.74 0.89 0.43 0.59 21.5 0.68 1.00 1.00 1.00 0.56 0.79 0.95 0.47 0.64 23.5 0.71 1.00 1.00 1.00 0.59 0.84 1.00 0.51 0.69
AMERICAN FOREST & PAPER ASSOCIATION
149ASD/LRFD MANUAL FOR ENGINEERED WOOD CONSTRUCTION M
1 6 : FIR
E D ES
IG N
16
Table M16.2-3 Design Load Ratios for Compression Members Exposed on Three Sides
(Structural Calculations at Standard Reference Conditions: CM = 1.0, Ct = 1.0, Ci = 1.0) (Protected Surface in Depth Direction)
Notes: 1. Tabulated values assume bending in the width direction. 2. Tabulated values conservatively assume column buckling failure. For rela-
tively short, highly loaded columns, a more rigorous analysis using the NDS provisions will increase the design load ratio, Rs.
Table M16.2-3A Southern Pine Structural Glued Laminated Timbers
Table M16.2-3B Western Species Structural Glued Laminated Timbers
Rating 1-HOUR 1.5-HOUR 2-HOUR Rating 1-HOUR 1.5-HOUR 2-HOUR Col. Width 5 6.75 8.5 10.5 6.75 8.5 10.5 8.5 10.5 Col. Width 5.125 6.75 8.75 10.75 6.75 8.75 10.75 8.75 10.75 Col. Depth Design Load Ratio, Rs Col. Depth Design Load Ratio, Rs
5.5 0.03 6 0.04 6.875 0.03 0.15 0.02 7.5 0.04 0.16 0.02 8.25 0.03 0.16 0.30 0.02 0.10 0.02 9 0.04 0.17 0.33 0.03 0.10 0.03
9.625 0.04 0.17 0.32 0.47 0.03 0.10 0.22 0.02 0.09 10.5 0.04 0.17 0.34 0.49 0.03 0.11 0.22 0.03 0.10 11 0.04 0.17 0.33 0.48 0.03 0.11 0.22 0.02 0.09 12 0.05 0.18 0.35 0.51 0.03 0.11 0.23 0.03 0.10
12.375 0.04 0.18 0.33 0.49 0.03 0.11 0.23 0.03 0.10 13.5 0.05 0.18 0.36 0.52 0.03 0.11 0.24 0.03 0.11 13.75 0.04 0.18 0.34 0.50 0.03 0.12 0.24 0.03 0.10 15 0.05 0.18 0.36 0.53 0.03 0.12 0.24 0.03 0.11
15.125 0.04 0.18 0.34 0.51 0.03 0.12 0.24 0.03 0.10 16.5 0.05 0.18 0.37 0.53 0.03 0.12 0.25 0.03 0.11 16.5 0.04 0.18 0.35 0.51 0.03 0.12 0.25 0.03 0.10 18 0.05 0.19 0.37 0.54 0.03 0.12 0.25 0.04 0.12
17.875 0.04 0.19 0.35 0.52 0.03 0.12 0.25 0.03 0.11 19.5 0.05 0.19 0.38 0.54 0.03 0.12 0.25 0.04 0.12 19.25 0.04 0.19 0.35 0.52 0.03 0.12 0.25 0.03 0.11 21 0.05 0.19 0.38 0.55 0.03 0.12 0.26 0.04 0.12
20.625 0.04 0.19 0.35 0.53 0.03 0.12 0.26 0.03 0.11 22.5 0.05 0.19 0.38 0.55 0.03 0.13 0.26 0.04 0.12 22 0.04 0.19 0.36 0.53 0.03 0.12 0.26 0.03 0.11 24 0.05 0.19 0.38 0.55 0.03 0.13 0.26 0.04 0.12
23.375 0.04 0.19 0.36 0.53 0.03 0.13 0.26 0.03 0.11 25.5 0.05 0.19 0.38 0.56 0.03 0.13 0.26 0.04 0.12 24.75 0.04 0.19 0.36 0.53 0.03 0.13 0.26 0.03 0.11 27 0.05 0.19 0.39 0.56 0.03 0.13 0.26 0.04 0.13
26.125 0.04 0.19 0.36 0.54 0.03 0.13 0.26 0.03 0.11 28.5 0.05 0.19 0.39 0.56 0.03 0.13 0.27 0.04 0.13 27.5 0.04 0.19 0.36 0.54 0.03 0.13 0.26 0.03 0.11 30 0.05 0.19 0.39 0.56 0.03 0.13 0.27 0.04 0.13
28.875 0.04 0.19 0.36 0.54 0.03 0.13 0.27 0.03 0.11 31.5 0.05 0.19 0.39 0.56 0.03 0.13 0.27 0.04 0.13 30.25 0.04 0.19 0.37 0.54 0.03 0.13 0.27 0.03 0.11 33 0.05 0.20 0.39 0.56 0.03 0.13 0.27 0.04 0.13
31.625 0.04 0.19 0.37 0.54 0.03 0.13 0.27 0.03 0.11 34.5 0.05 0.20 0.39 0.57 0.03 0.13 0.27 0.04 0.13 33 0.04 0.20 0.37 0.54 0.03 0.13 0.27 0.03 0.12 36 0.05 0.20 0.39 0.57 0.03 0.13 0.27 0.04 0.13
34.375 0.04 0.20 0.37 0.55 0.03 0.13 0.27 0.03 0.12 37.5 0.20 0.39 0.57 0.03 0.13 0.27 0.04 0.13 35.75 0.04 0.20 0.37 0.55 0.03 0.13 0.27 0.03 0.12 39 0.20 0.39 0.57 0.03 0.13 0.27 0.04 0.13
37.125 0.20 0.37 0.55 0.03 0.13 0.27 0.03 0.12 40.5 0.20 0.40 0.57 0.03 0.13 0.27 0.04 0.13 38.5 0.20 0.37 0.55 0.03 0.13 0.27 0.03 0.12 42 0.20 0.40 0.57 0.03 0.13 0.27 0.04 0.13
39.875 0.20 0.37 0.55 0.03 0.13 0.27 0.03 0.12 43.5 0.20 0.40 0.57 0.03 0.13 0.27 0.04 0.13 41.25 0.20 0.37 0.55 0.03 0.13 0.27 0.03 0.12 45 0.20 0.40 0.57 0.03 0.13 0.27 0.04 0.13
42.625 0.20 0.37 0.55 0.03 0.13 0.27 0.03 0.12 46.5 0.20 0.40 0.57 0.03 0.13 0.28 0.04 0.13 44 0.20 0.37 0.55 0.03 0.13 0.27 0.03 0.12 48 0.20 0.40 0.57 0.03 0.13 0.28 0.04 0.13
45.375 0.20 0.37 0.55 0.03 0.13 0.27 0.03 0.12 49.5 0.40 0.58 0.03 0.13 0.28 0.04 0.13 46.75 0.20 0.37 0.55 0.03 0.13 0.28 0.03 0.12 51 0.40 0.58 0.03 0.13 0.28 0.04 0.13
48.125 0.20 0.37 0.55 0.03 0.13 0.28 0.03 0.12 52.5 0.40 0.58 0.03 0.13 0.28 0.04 0.13 49.5 0.37 0.56 0.13 0.28 0.03 0.12 54 0.40 0.58 0.13 0.28 0.04 0.13
50.875 0.38 0.56 0.13 0.28 0.03 0.12 55.5 0.40 0.58 0.13 0.28 0.04 0.13 52.25 0.38 0.56 0.13 0.28 0.03 0.12 57 0.40 0.58 0.13 0.28 0.04 0.13
53.625 0.38 0.56 0.13 0.28 0.03 0.12 58.5 0.40 0.58 0.13 0.28 0.04 0.13 55 0.38 0.56 0.13 0.28 0.03 0.12 60 0.40 0.58 0.14 0.28 0.04 0.13
56.375 0.38 0.56 0.13 0.28 0.03 0.12 61.5 0.40 0.58 0.14 0.28 0.04 0.13 57.75 0.38 0.56 0.13 0.28 0.03 0.12 63 0.40 0.58 0.14 0.28 0.04 0.13
59.125 0.38 0.56 0.14 0.28 0.03 0.12 64.5 0.58 0.14 0.28 0.13 60.5 0.38 0.56 0.14 0.28 0.03 0.12 66 0.58 0.14 0.28 0.13
61.875 0.38 0.56 0.14 0.28 0.03 0.12 67.5 0.58 0.14 0.28 0.13 63.25 0.38 0.56 0.14 0.28 0.03 0.12 69 0.58 0.14 0.28 0.14
64.625 0.56 0.28 0.12 70.5 0.58 0.28 0.14 66 0.56 0.28 0.12 72 0.58 0.28 0.14
67.375 0.56 0.28 0.12 73.5 0.58 0.28 0.14 68.75 0.56 0.28 0.12 75 0.58 0.28 0.14
70.125 0.56 0.28 0.12 76.5 0.58 0.28 0.14 71.5 0.56 0.28 0.12 78 0.58 0.28 0.14
72.875 0.56 0.28 0.12 79.5 0.58 0.28 0.14 74.25 0.56 0.28 0.12 81 0.58 0.28 0.14
75.625 0.56 0.28 0.12 77 0.56 0.28 0.12
Table M16.2-3C Solid Sawn Timbers Rating 1-HOUR 1.5-HOUR 2-HOUR
Col. Width 5.5 7.5 9.5 11.5 7.5 9.5 11.5 9.5 11.5 Col. Depth Design Load Ratio, Rs
5.5 0.06 7.5 0.06 0.22 0.05 9.5 0.07 0.23 0.39 0.05 0.16 0.05 11.5 0.07 0.24 0.41 0.56 0.06 0.17 0.29 0.05 0.13 13.5 0.07 0.25 0.42 0.57 0.06 0.18 0.30 0.06 0.14 15.5 0.07 0.25 0.43 0.58 0.06 0.18 0.31 0.06 0.15 17.5 0.08 0.26 0.44 0.59 0.06 0.18 0.31 0.06 0.15 19.5 0.08 0.26 0.44 0.60 0.07 0.19 0.32 0.06 0.16 21.5 0.08 0.26 0.45 0.60 0.07 0.19 0.32 0.06 0.16 23.5 0.08 0.26 0.45 0.61 0.07 0.19 0.33 0.07 0.16
AMERICAN WOOD COUNCIL
150 M16: FIRE DESIGN
Table M16.2-4 Design Load Ratios for Compression Members Exposed on Three Sides
(Structural Calculations at Standard Reference Conditions: CM = 1.0, Ct = 1.0, Ci = 1.0) (Protected Surface in Width Direction)
Notes: 1. Tabulated values assume bending in the width direction. 2. Tabulated values conservatively assume column buckling failure. For rela-
tively short, highly loaded columns, a more rigorous analysis using the NDS provisions will increase the design load ratio, Rs.
Table M16.2-4A Southern Pine Structural Glued Laminated Timbers
Table M16.2-4B Western Species Structural Glued Laminated Timbers
Rating 1-HOUR 1.5-HOUR 2-HOUR Rating 1-HOUR 1.5-HOUR 2-HOUR Col. Width 5 6.75 8.5 10.5 6.75 8.5 10.5 8.5 10.5 Col. Width 5.125 6.75 8.75 10.75 6.75 8.75 10.75 8.75 10.75 Col. Depth Design Load Ratio, Rs Col. Depth Design Load Ratio, Rs
5.5 0.18 6 0.22 6.875 0.25 0.38 0.14 7.5 0.29 0.42 0.17 8.25 0.30 0.45 0.56 0.20 0.28 0.12 9 0.33 0.48 0.61 0.22 0.32 0.16
9.625 0.33 0.50 0.62 0.72 0.24 0.34 0.43 0.17 0.24 10.5 0.36 0.53 0.67 0.77 0.26 0.37 0.47 0.21 0.28 11 0.36 0.54 0.67 0.78 0.28 0.39 0.49 0.21 0.29 12 0.39 0.56 0.71 0.82 0.29 0.42 0.52 0.25 0.34
12.375 0.38 0.57 0.70 0.82 0.30 0.42 0.53 0.25 0.34 13.5 0.41 0.59 0.75 0.86 0.32 0.45 0.56 0.28 0.38 13.75 0.39 0.59 0.73 0.85 0.32 0.45 0.57 0.27 0.37 15 0.42 0.61 0.77 0.89 0.34 0.48 0.60 0.31 0.41
15.125 0.41 0.61 0.76 0.88 0.34 0.48 0.60 0.29 0.40 16.5 0.43 0.63 0.80 0.92 0.35 0.50 0.62 0.33 0.44 16.5 0.42 0.63 0.78 0.90 0.35 0.50 0.62 0.31 0.43 18 0.44 0.64 0.81 0.94 0.37 0.51 0.65 0.34 0.46
17.875 0.42 0.64 0.79 0.92 0.36 0.51 0.65 0.32 0.45 19.5 0.45 0.65 0.83 0.96 0.38 0.53 0.67 0.36 0.48 19.25 0.43 0.65 0.81 0.94 0.37 0.53 0.66 0.34 0.47 21 0.46 0.66 0.84 0.97 0.39 0.54 0.68 0.37 0.50
20.625 0.44 0.66 0.82 0.95 0.38 0.54 0.68 0.35 0.48 22.5 0.47 0.67 0.85 0.98 0.39 0.55 0.70 0.38 0.51 22 0.45 0.67 0.83 0.97 0.39 0.55 0.69 0.36 0.49 24 0.47 0.68 0.86 1.00 0.40 0.56 0.71 0.39 0.53
23.375 0.45 0.68 0.84 0.98 0.40 0.56 0.70 0.37 0.51 25.5 0.48 0.69 0.87 1.00 0.41 0.57 0.72 0.40 0.54 24.75 0.45 0.68 0.85 0.99 0.40 0.57 0.72 0.37 0.52 27 0.48 0.69 0.88 1.00 0.41 0.58 0.73 0.40 0.55
26.125 0.46 0.69 0.86 1.00 0.41 0.58 0.73 0.38 0.53 28.5 0.48 0.70 0.89 1.00 0.42 0.59 0.74 0.41 0.56 27.5 0.46 0.70 0.86 1.00 0.41 0.58 0.73 0.39 0.53 30 0.49 0.70 0.90 1.00 0.42 0.59 0.75 0.42 0.56
28.875 0.47 0.70 0.87 1.00 0.42 0.59 0.74 0.39 0.54 31.5 0.49 0.71 0.90 1.00 0.43 0.60 0.75 0.42 0.57 30.25 0.47 0.71 0.88 1.00 0.42 0.59 0.75 0.40 0.55 33 0.49 0.71 0.91 1.00 0.43 0.60 0.76 0.43 0.58
31.625 0.47 0.71 0.88 1.00 0.43 0.60 0.75 0.40 0.55 34.5 0.50 0.72 0.91 1.00 0.43 0.61 0.77 0.43 0.58 33 0.47 0.71 0.89 1.00 0.43 0.60 0.76 0.41 0.56 36 0.50 0.72 0.92 1.00 0.44 0.61 0.77 0.44 0.59
34.375 0.48 0.72 0.89 1.00 0.43 0.61 0.77 0.41 0.57 37.5 0.72 0.92 1.00 0.44 0.62 0.78 0.44 0.59 35.75 0.48 0.72 0.89 1.00 0.43 0.61 0.77 0.41 0.57 39 0.73 0.92 1.00 0.44 0.62 0.78 0.44 0.60
37.125 0.72 0.90 1.00 0.44 0.62 0.78 0.42 0.57 40.5 0.73 0.93 1.00 0.44 0.62 0.79 0.45 0.60 38.5 0.73 0.90 1.00 0.44 0.62 0.78 0.42 0.58 42 0.73 0.93 1.00 0.45 0.63 0.79 0.45 0.61
39.875 0.73 0.90 1.00 0.44 0.62 0.78 0.42 0.58 43.5 0.73 0.93 1.00 0.45 0.63 0.79 0.45 0.61 41.25 0.73 0.91 1.00 0.44 0.63 0.79 0.43 0.59 45 0.74 0.94 1.00 0.45 0.63 0.80 0.45 0.61
42.625 0.73 0.91 1.00 0.45 0.63 0.79 0.43 0.59 46.5 0.74 0.94 1.00 0.45 0.64 0.80 0.46 0.62 44 0.74 0.91 1.00 0.45 0.63 0.79 0.43 0.59 48 0.74 0.94 1.00 0.45 0.64 0.80 0.46 0.62
45.375 0.74 0.92 1.00 0.45 0.63 0.80 0.43 0.60 49.5 0.94 1.00 0.45 0.64 0.81 0.46 0.62 46.75 0.74 0.92 1.00 0.45 0.64 0.80 0.43 0.60 51 0.95 1.00 0.46 0.64 0.81 0.46 0.63
48.125 0.74 0.92 1.00 0.45 0.64 0.80 0.44 0.60 52.5 0.95 1.00 0.46 0.64 0.81 0.46 0.63 49.5 0.92 1.00 0.64 0.81 0.44 0.60 54 0.95 1.00 0.65 0.81 0.47 0.63
50.875 0.92 1.00 0.64 0.81 0.44 0.61 55.5 0.95 1.00 0.65 0.82 0.47 0.63 52.25 0.93 1.00 0.64 0.81 0.44 0.61 57 0.95 1.00 0.65 0.82 0.47 0.63
53.625 0.93 1.00 0.65 0.81 0.44 0.61 58.5 0.95 1.00 0.65 0.82 0.47 0.64 55 0.93 1.00 0.65 0.82 0.44 0.61 60 0.96 1.00 0.65 0.82 0.47 0.64
56.375 0.93 1.00 0.65 0.82 0.45 0.62 61.5 0.96 1.00 0.65 0.82 0.47 0.64 57.75 0.93 1.00 0.65 0.82 0.45 0.62 63 0.96 1.00 0.66 0.83 0.48 0.64
59.125 0.93 1.00 0.65 0.82 0.45 0.62 64.5 1.00 0.66 0.83 0.64 60.5 0.94 1.00 0.65 0.82 0.45 0.62 66 1.00 0.66 0.83 0.65
61.875 0.94 1.00 0.66 0.82 0.45 0.62 67.5 1.00 0.66 0.83 0.65 63.25 0.94 1.00 0.66 0.83 0.45 0.62 69 1.00 0.66 0.83 0.65
64.625 1.00 0.83 0.62 70.5 1.00 0.83 0.65 66 1.00 0.83 0.63 72 1.00 0.83 0.65
67.375 1.00 0.83 0.63 73.5 1.00 0.84 0.65 68.75 1.00 0.83 0.63 75 1.00 0.84 0.65
70.125 1.00 0.83 0.63 76.5 1.00 0.84 0.65 71.5 1.00 0.83 0.63 78 1.00 0.84 0.66
72.875 1.00 0.84 0.63 79.5 1.00 0.84 0.66 74.25 1.00 0.84 0.63 81 1.00 0.84 0.66
75.625 1.00 0.84 0.63 77 1.00 0.84 0.64
Table M16.2-4C Solid Sawn Timbers Rating 1-HOUR 1.5-HOUR 2-HOUR
Col. Width 5.5 7.5 9.5 11.5 7.5 9.5 11.5 9.5 11.5 Col. Depth Design Load Ratio, Rs
5.5 0.21 7.5 0.32 0.46 0.20 9.5 0.38 0.55 0.67 0.28 0.38 0.20 11.5 0.42 0.61 0.74 0.84 0.34 0.46 0.55 0.27 0.35 13.5 0.45 0.65 0.79 0.89 0.38 0.51 0.61 0.32 0.41 15.5 0.47 0.68 0.83 0.94 0.41 0.55 0.66 0.36 0.46 17.5 0.49 0.71 0.86 0.97 0.43 0.58 0.69 0.38 0.49 19.5 0.50 0.73 0.88 0.99 0.45 0.60 0.72 0.41 0.52 21.5 0.51 0.74 0.90 1.00 0.46 0.62 0.75 0.43 0.55 23.5 0.52 0.75 0.92 1.00 0.47 0.64 0.77 0.44 0.57
AMERICAN FOREST & PAPER ASSOCIATION
151ASD/LRFD MANUAL FOR ENGINEERED WOOD CONSTRUCTION M
1 6 : FIR
E D ES
IG N
16
Table M16.2-5 Design Load Ratios for Compression Members Exposed on Four Sides
(Structural Calculations at Standard Reference Conditions: CM = 1.0, Ct = 1.0, Ci = 1.0)
Table M16.2-5A Southern Pine Structural Glued Laminated Timbers
Table M16.2-5B Western Species Structural Glued Laminated Timbers
Rating 1-HOUR 1.5-HOUR 2-HOUR Rating 1-HOUR 1.5-HOUR 2-HOUR Col. Width 5 6.75 8.5 10.5 6.75 8.5 10.5 8.5 10.5 Col. Width 5.125 6.75 8.75 10.75 6.75 8.75 10.75 8.75 10.75 Col. Depth Design Load Ratio, Rs Col. Depth Design Load Ratio, Rs
5.5 0.02 6 0.02 6.875 0.02 0.10 0.01 7.5 0.03 0.11 0.01 8.25 0.03 0.12 0.22 0.01 0.06 0.01 9 0.03 0.12 0.25 0.02 0.06 0.01
9.625 0.03 0.13 0.24 0.36 0.02 0.07 0.14 0.01 0.04 10.5 0.04 0.14 0.27 0.39 0.02 0.07 0.15 0.02 0.06 11 0.03 0.14 0.26 0.39 0.02 0.08 0.16 0.01 0.05 12 0.04 0.14 0.29 0.42 0.02 0.08 0.17 0.02 0.07
12.375 0.03 0.15 0.28 0.41 0.02 0.08 0.17 0.02 0.06 13.5 0.04 0.15 0.30 0.44 0.02 0.09 0.18 0.02 0.08 13.75 0.03 0.15 0.29 0.43 0.02 0.09 0.18 0.02 0.07 15 0.04 0.16 0.31 0.45 0.02 0.09 0.19 0.03 0.08
15.125 0.03 0.16 0.30 0.44 0.02 0.09 0.19 0.02 0.07 16.5 0.04 0.16 0.32 0.47 0.02 0.10 0.20 0.03 0.09 16.5 0.03 0.16 0.30 0.45 0.02 0.10 0.20 0.02 0.08 18 0.04 0.17 0.33 0.48 0.03 0.10 0.21 0.03 0.09
17.875 0.04 0.16 0.31 0.46 0.03 0.10 0.21 0.02 0.08 19.5 0.04 0.17 0.34 0.49 0.03 0.10 0.22 0.03 0.10 19.25 0.04 0.17 0.32 0.47 0.03 0.10 0.22 0.02 0.09 21 0.04 0.17 0.34 0.49 0.03 0.11 0.22 0.03 0.10
20.625 0.04 0.17 0.32 0.48 0.03 0.11 0.22 0.02 0.09 22.5 0.04 0.17 0.35 0.50 0.03 0.11 0.23 0.03 0.10 22 0.04 0.17 0.33 0.48 0.03 0.11 0.22 0.02 0.09 24 0.05 0.18 0.35 0.51 0.03 0.11 0.23 0.03 0.10
23.375 0.04 0.17 0.33 0.49 0.03 0.11 0.23 0.02 0.09 25.5 0.05 0.18 0.36 0.51 0.03 0.11 0.23 0.03 0.11 24.75 0.04 0.18 0.33 0.49 0.03 0.11 0.23 0.03 0.10 27 0.05 0.18 0.36 0.52 0.03 0.11 0.24 0.03 0.11
26.125 0.04 0.18 0.34 0.50 0.03 0.11 0.24 0.03 0.10 28.5 0.05 0.18 0.36 0.52 0.03 0.12 0.24 0.03 0.11 27.5 0.04 0.18 0.34 0.50 0.03 0.12 0.24 0.03 0.10 30 0.05 0.18 0.36 0.53 0.03 0.12 0.24 0.03 0.11
28.875 0.04 0.18 0.34 0.50 0.03 0.12 0.24 0.03 0.10 31.5 0.05 0.18 0.37 0.53 0.03 0.12 0.24 0.03 0.11 30.25 0.04 0.18 0.34 0.51 0.03 0.12 0.24 0.03 0.10 33 0.05 0.18 0.37 0.53 0.03 0.12 0.25 0.03 0.11
31.625 0.04 0.18 0.34 0.51 0.03 0.12 0.24 0.03 0.10 34.5 0.05 0.18 0.37 0.53 0.03 0.12 0.25 0.04 0.12 33 0.04 0.18 0.35 0.51 0.03 0.12 0.25 0.03 0.10 36 0.05 0.19 0.37 0.54 0.03 0.12 0.25 0.04 0.12
34.375 0.04 0.18 0.35 0.52 0.03 0.12 0.25 0.03 0.10 37.5 0.19 0.37 0.54 0.03 0.12 0.25 0.04 0.12 35.75 0.04 0.19 0.35 0.52 0.03 0.12 0.25 0.03 0.11 39 0.19 0.38 0.54 0.03 0.12 0.25 0.04 0.12
37.125 0.19 0.35 0.52 0.03 0.12 0.25 0.03 0.11 40.5 0.19 0.38 0.54 0.03 0.12 0.25 0.04 0.12 38.5 0.19 0.35 0.52 0.03 0.12 0.25 0.03 0.11 42 0.19 0.38 0.55 0.03 0.12 0.26 0.04 0.12
39.875 0.19 0.35 0.52 0.03 0.12 0.25 0.03 0.11 43.5 0.19 0.38 0.55 0.03 0.12 0.26 0.04 0.12 41.25 0.19 0.35 0.53 0.03 0.12 0.26 0.03 0.11 45 0.19 0.38 0.55 0.03 0.13 0.26 0.04 0.12
42.625 0.19 0.36 0.53 0.03 0.12 0.26 0.03 0.11 46.5 0.19 0.38 0.55 0.03 0.13 0.26 0.04 0.12 44 0.19 0.36 0.53 0.03 0.12 0.26 0.03 0.11 48 0.19 0.38 0.55 0.03 0.13 0.26 0.04 0.12
45.375 0.19 0.36 0.53 0.03 0.13 0.26 0.03 0.11 49.5 0.38 0.55 0.03 0.13 0.26 0.04 0.12 46.75 0.19 0.36 0.53 0.03 0.13 0.26 0.03 0.11 51 0.38 0.56 0.03 0.13 0.26 0.04 0.12
48.125 0.19 0.36 0.53 0.03 0.13 0.26 0.03 0.11 52.5 0.39 0.56 0.03 0.13 0.26 0.04 0.12 49.5 0.36 0.53 0.13 0.26 0.03 0.11 54 0.39 0.56 0.13 0.26 0.04 0.13
50.875 0.36 0.54 0.13 0.26 0.03 0.11 55.5 0.39 0.56 0.13 0.26 0.04 0.13 52.25 0.36 0.54 0.13 0.26 0.03 0.11 57 0.39 0.56 0.13 0.27 0.04 0.13
53.625 0.36 0.54 0.13 0.26 0.03 0.11 58.5 0.39 0.56 0.13 0.27 0.04 0.13 55 0.36 0.54 0.13 0.26 0.03 0.11 60 0.39 0.56 0.13 0.27 0.04 0.13
56.375 0.36 0.54 0.13 0.27 0.03 0.11 61.5 0.39 0.56 0.13 0.27 0.04 0.13 57.75 0.36 0.54 0.13 0.27 0.03 0.11 63 0.39 0.56 0.13 0.27 0.04 0.13
59.125 0.37 0.54 0.13 0.27 0.03 0.11 64.5 0.56 0.13 0.27 0.13 60.5 0.37 0.54 0.13 0.27 0.03 0.11 66 0.56 0.13 0.27 0.13
61.875 0.37 0.54 0.13 0.27 0.03 0.11 67.5 0.57 0.13 0.27 0.13 63.25 0.37 0.54 0.13 0.27 0.03 0.11 69 0.57 0.13 0.27 0.13
64.625 0.54 0.27 0.12 70.5 0.57 0.27 0.13 66 0.54 0.27 0.12 72 0.57 0.27 0.13
67.375 0.55 0.27 0.12 73.5 0.57 0.27 0.13 68.75 0.55 0.27 0.12 75 0.57 0.27 0.13
70.125 0.55 0.27 0.12 76.5 0.57 0.27 0.13 71.5 0.55 0.27 0.12 78 0.57 0.27 0.13
72.875 0.55 0.27 0.12 79.5 0.57 0.27 0.13 74.25 0.55 0.27 0.12 81 0.57 0.27 0.13
75.625 0.55 0.27 0.12 77 0.55 0.27 0.12
Table M16.2-5C Solid Sawn Timbers Rating 1-HOUR 1.5-HOUR 2-HOUR
Col. Width 5.5 7.5 9.5 11.5 7.5 9.5 11.5 9.5 11.5 Col. Depth Design Load Ratio, Rs
5.5 0.03 7.5 0.04 0.15 0.02 9.5 0.05 0.18 0.30 0.04 0.10 0.03 11.5 0.06 0.20 0.33 0.45 0.04 0.12 0.21 0.03 0.08 13.5 0.06 0.21 0.36 0.48 0.05 0.14 0.23 0.04 0.10 15.5 0.06 0.22 0.37 0.51 0.05 0.15 0.25 0.04 0.11 17.5 0.07 0.23 0.39 0.52 0.05 0.15 0.26 0.05 0.12 19.5 0.07 0.23 0.40 0.54 0.06 0.16 0.27 0.05 0.13 21.5 0.07 0.24 0.40 0.55 0.06 0.16 0.28 0.05 0.13 23.5 0.07 0.24 0.41 0.56 0.06 0.17 0.29 0.06 0.14
Notes: 1. Tabulated values assume bending in the width direction. 2. Tabulated values conservatively assume column buckling failure. For rela-
tively short, highly loaded columns, a more rigorous analysis using the NDS provisions will increase the design load ratio, Rs.
AMERICAN WOOD COUNCIL
152 M16: FIRE DESIGN
Table M16.2-6 Design Load Ratios for Tension Members Exposed on Three Sides (Structural Calculations at Standard Reference Conditions: CD = 1.0, CM = 1.0, Ct = 1.0, Ci = 1.0)
(Protected Surface in Depth Direction)
Table M16.2-6A Southern Pine Structural Glued Laminated Timbers
Table M16.2-6B Western Species Structural Glued Laminated Timbers
Rating 1-HOUR 1.5-HOUR 2-HOUR Rating 1-HOUR 1.5-HOUR 2-HOUR Beam Width 5 6.75 8.5 10.5 6.75 8.5 10.5 8.5 10.5 Beam Width 5.125 6.75 8.75 10.75 6.75 8.75 10.75 8.75 10.75 Beam Depth Design Load Ratio, Rs Beam Depth Design Load Ratio, Rs
5.5 0.54 0.89 1.00 1.00 0.40 0.64 0.81 0.31 0.48 6 0.59 0.93 1.00 1.00 0.43 0.71 0.89 0.37 0.55 6.875 0.59 0.98 1.00 1.00 0.47 0.75 0.95 0.39 0.61 7.5 0.64 1.00 1.00 1.00 0.49 0.81 1.00 0.46 0.68 8.25 0.62 1.00 1.00 1.00 0.51 0.82 1.00 0.45 0.70 9 0.68 1.00 1.00 1.00 0.53 0.88 1.00 0.51 0.76
9.625 0.65 1.00 1.00 1.00 0.54 0.87 1.00 0.49 0.76 10.5 0.70 1.00 1.00 1.00 0.56 0.93 1.00 0.55 0.82 11 0.67 1.00 1.00 1.00 0.57 0.91 1.00 0.52 0.81 12 0.72 1.00 1.00 1.00 0.58 0.97 1.00 0.58 0.86
12.375 0.68 1.00 1.00 1.00 0.59 0.93 1.00 0.54 0.84 13.5 0.73 1.00 1.00 1.00 0.60 0.99 1.00 0.60 0.90 13.75 0.69 1.00 1.00 1.00 0.60 0.96 1.00 0.56 0.87 15 0.75 1.00 1.00 1.00 0.61 1.00 1.00 0.62 0.93
15.125 0.70 1.00 1.00 1.00 0.61 0.98 1.00 0.58 0.90 16.5 0.76 1.00 1.00 1.00 0.62 1.00 1.00 0.64 0.95 16.5 0.71 1.00 1.00 1.00 0.62 0.99 1.00 0.59 0.92 18 0.76 1.00 1.00 1.00 0.63 1.00 1.00 0.65 0.97
17.875 0.72 1.00 1.00 1.00 0.63 1.00 1.00 0.60 0.93 19.5 0.77 1.00 1.00 1.00 0.64 1.00 1.00 0.66 0.98 19.25 0.72 1.00 1.00 1.00 0.64 1.00 1.00 0.61 0.95 21 0.78 1.00 1.00 1.00 0.65 1.00 1.00 0.67 1.00
20.625 0.73 1.00 1.00 1.00 0.65 1.00 1.00 0.62 0.96 22.5 0.78 1.00 1.00 1.00 0.65 1.00 1.00 0.68 1.00 22 0.73 1.00 1.00 1.00 0.65 1.00 1.00 0.62 0.97 24 0.78 1.00 1.00 1.00 0.66 1.00 1.00 0.69 1.00
23.375 0.74 1.00 1.00 1.00 0.66 1.00 1.00 0.63 0.98 25.5 0.79 1.00 1.00 1.00 0.66 1.00 1.00 0.69 1.00 24.75 0.74 1.00 1.00 1.00 0.66 1.00 1.00 0.64 0.99 27 0.79 1.00 1.00 1.00 0.67 1.00 1.00 0.70 1.00
26.125 0.74 1.00 1.00 1.00 0.67 1.00 1.00 0.64 1.00 28.5 0.79 1.00 1.00 1.00 0.67 1.00 1.00 0.70 1.00 27.5 0.75 1.00 1.00 1.00 0.67 1.00 1.00 0.65 1.00 30 0.80 1.00 1.00 1.00 0.68 1.00 1.00 0.71 1.00
28.875 0.75 1.00 1.00 1.00 0.67 1.00 1.00 0.65 1.00 31.5 0.80 1.00 1.00 1.00 0.68 1.00 1.00 0.71 1.00 30.25 0.75 1.00 1.00 1.00 0.68 1.00 1.00 0.65 1.00 33 0.80 1.00 1.00 1.00 0.68 1.00 1.00 0.71 1.00
31.625 0.75 1.00 1.00 1.00 0.68 1.00 1.00 0.66 1.00 34.5 0.80 1.00 1.00 1.00 0.68 1.00 1.00 0.72 1.00 33 0.75 1.00 1.00 1.00 0.68 1.00 1.00 0.66 1.00 36 0.81 1.00 1.00 1.00 0.69 1.00 1.00 0.72 1.00
34.375 0.76 1.00 1.00 1.00 0.68 1.00 1.00 0.66 1.00 37.5 1.00 1.00 1.00 0.69 1.00 1.00 0.72 1.00 35.75 0.76 1.00 1.00 1.00 0.68 1.00 1.00 0.66 1.00 39 1.00 1.00 1.00 0.69 1.00 1.00 0.73 1.00
37.125 1.00 1.00 1.00 0.69 1.00 1.00 0.67 1.00 40.5 1.00 1.00 1.00 0.69 1.00 1.00 0.73 1.00 38.5 1.00 1.00 1.00 0.69 1.00 1.00 0.67 1.00 42 1.00 1.00 1.00 0.69 1.00 1.00 0.73 1.00
39.875 1.00 1.00 1.00 0.69 1.00 1.00 0.67 1.00 43.5 1.00 1.00 1.00 0.69 1.00 1.00 0.73 1.00 41.25 1.00 1.00 1.00 0.69 1.00 1.00 0.67 1.00 45 1.00 1.00 1.00 0.70 1.00 1.00 0.73 1.00
42.625 1.00 1.00 1.00 0.69 1.00 1.00 0.68 1.00 46.5 1.00 1.00 1.00 0.70 1.00 1.00 0.74 1.00 44 1.00 1.00 1.00 0.69 1.00 1.00 0.68 1.00 48 1.00 1.00 1.00 0.70 1.00 1.00 0.74 1.00
45.375 1.00 1.00 1.00 0.70 1.00 1.00 0.68 1.00 49.5 1.00 1.00 1.00 1.00 0.74 1.00 46.75 1.00 1.00 1.00 0.70 1.00 1.00 0.68 1.00 51 1.00 1.00 1.00 1.00 0.74 1.00
48.125 1.00 1.00 1.00 0.70 1.00 1.00 0.68 1.00 52.5 1.00 1.00 1.00 1.00 0.74 1.00 49.5 1.00 1.00 1.00 1.00 0.68 1.00 54 1.00 1.00 1.00 1.00 0.74 1.00
50.875 1.00 1.00 1.00 1.00 0.68 1.00 55.5 1.00 1.00 1.00 1.00 0.74 1.00 52.25 1.00 1.00 1.00 1.00 0.69 1.00 57 1.00 1.00 1.00 1.00 0.75 1.00
53.625 1.00 1.00 1.00 1.00 0.69 1.00 58.5 1.00 1.00 1.00 1.00 0.75 1.00 55 1.00 1.00 1.00 1.00 0.69 1.00 60 1.00 1.00 1.00 1.00 0.75 1.00
56.375 1.00 1.00 1.00 1.00 0.69 1.00 61.5 1.00 1.00 1.00 1.00 0.75 1.00 57.75 1.00 1.00 1.00 1.00 0.69 1.00 63 1.00 1.00 1.00 1.00 0.75 1.00
59.125 1.00 1.00 1.00 1.00 0.69 1.00 64.5 1.00 1.00 1.00 60.5 1.00 1.00 1.00 1.00 0.69 1.00 66 1.00 1.00 1.00
61.875 1.00 1.00 1.00 1.00 0.69 1.00 67.5 1.00 1.00 1.00 63.25 1.00 1.00 1.00 1.00 0.69 1.00 69 1.00 1.00 1.00
64.625 1.00 1.00 1.00 70.5 1.00 1.00 1.00 66 1.00 1.00 1.00 72 1.00 1.00 1.00
67.375 1.00 1.00 1.00 73.5 1.00 1.00 1.00 68.75 1.00 1.00 1.00 75 1.00 1.00 1.00
70.125 1.00 1.00 1.00 76.5 1.00 1.00 1.00 71.5 1.00 1.00 1.00 78 1.00 1.00 1.00
72.875 1.00 1.00 1.00 79.5 1.00 1.00 1.00 74.25 1.00 1.00 1.00 81 1.00 1.00 1.00
75.625 1.00 1.00 1.00 77 1.00 1.00 1.00
Table M16.2-6C Solid Sawn Timbers Rating 1-HOUR 1.5-HOUR 2-HOUR
Beam Width 5.5 7.5 9.5 11.5 7.5 9.5 11.5 9.5 11.5 Beam Depth Design Load Ratio, Rs
5.5 0.66 1.00 1.00 1.00 0.52 0.73 0.88 0.40 0.55 7.5 0.75 1.00 1.00 1.00 0.63 0.90 1.00 0.55 0.74 9.5 0.80 1.00 1.00 1.00 0.70 0.99 1.00 0.64 0.86 11.5 0.83 1.00 1.00 1.00 0.74 1.00 1.00 0.69 0.93 13.5 0.85 1.00 1.00 1.00 0.77 1.00 1.00 0.73 0.98 15.5 0.87 1.00 1.00 1.00 0.79 1.00 1.00 0.76 1.00 17.5 0.88 1.00 1.00 1.00 0.81 1.00 1.00 0.78 1.00 19.5 0.89 1.00 1.00 1.00 0.83 1.00 1.00 0.80 1.00 21.5 0.90 1.00 1.00 1.00 0.84 1.00 1.00 0.81 1.00 23.5 0.91 1.00 1.00 1.00 0.85 1.00 1.00 0.82 1.00
AMERICAN FOREST & PAPER ASSOCIATION
153ASD/LRFD MANUAL FOR ENGINEERED WOOD CONSTRUCTION M
1 6 : FIR
E D ES
IG N
16
Table M16.2-7 Design Load Ratios for Tension Members Exposed on Three Sides (Structural Calculations at Standard Reference Conditions: CD = 1.0, CM = 1.0, Ct = 1.0, Ci = 1.0)
(Protected Surface in Width Direction)
Table M16.2-7A Southern Pine Glued Structural Laminated Timbers
Table M16.2-7B Western Species Structural Glued Laminated Timbers
Rating 1-HOUR 1.5-HOUR 2-HOUR Rating 1-HOUR 1.5-HOUR 2-HOUR Beam Width 5 6.75 8.5 10.5 6.75 8.5 10.5 8.5 10.5 Beam Width 5.125 6.75 8.75 10.75 6.75 8.75 10.75 8.75 10.75 Beam Depth Design Load Ratio, Rs Beam Depth Design Load Ratio, Rs
5.5 0.63 0.72 0.78 0.82 0.16 0.18 0.20 6 0.74 0.84 0.91 0.95 0.30 0.34 0.36 6.875 0.87 1.00 1.00 1.00 0.49 0.55 0.59 0.14 0.16 7.5 0.96 1.00 1.00 1.00 0.60 0.68 0.73 0.29 0.32 8.25 1.00 1.00 1.00 1.00 0.71 0.79 0.85 0.42 0.46 9 1.00 1.00 1.00 1.00 0.80 0.90 0.97 0.54 0.60
9.625 1.00 1.00 1.00 1.00 0.86 0.97 1.00 0.61 0.68 10.5 1.00 1.00 1.00 1.00 0.94 1.00 1.00 0.72 0.80 11 1.00 1.00 1.00 1.00 0.98 1.00 1.00 0.76 0.85 12 1.00 1.00 1.00 1.00 1.00 1.00 1.00 0.86 0.95
12.375 1.00 1.00 1.00 1.00 1.00 1.00 1.00 0.87 0.97 13.5 1.00 1.00 1.00 1.00 1.00 1.00 1.00 0.97 1.00 13.75 1.00 1.00 1.00 1.00 1.00 1.00 1.00 0.97 1.00 15 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
15.125 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 16.5 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 16.5 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 18 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
17.875 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 19.5 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 19.25 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 21 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
20.625 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 22.5 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 22 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 24 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
23.375 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 25.5 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 24.75 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 27 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
26.125 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 28.5 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 27.5 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 30 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
28.875 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 31.5 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 30.25 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 33 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
31.625 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 34.5 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 33 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 36 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
34.375 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 37.5 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 35.75 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 39 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
37.125 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 40.5 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 38.5 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 42 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
39.875 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 43.5 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 41.25 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 45 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
42.625 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 46.5 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 44 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 48 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
45.375 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 49.5 1.00 1.00 1.00 1.00 1.00 1.00 46.75 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 51 1.00 1.00 1.00 1.00 1.00 1.00
48.125 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 52.5 1.00 1.00 1.00 1.00 1.00 1.00 49.5 1.00 1.00 1.00 1.00 1.00 1.00 54 1.00 1.00 1.00 1.00 1.00 1.00
50.875 1.00 1.00 1.00 1.00 1.00 1.00 55.5 1.00 1.00 1.00 1.00 1.00 1.00 52.25 1.00 1.00 1.00 1.00 1.00 1.00 57 1.00 1.00 1.00 1.00 1.00 1.00
53.625 1.00 1.00 1.00 1.00 1.00 1.00 58.5 1.00 1.00 1.00 1.00 1.00 1.00 55 1.00 1.00 1.00 1.00 1.00 1.00 60 1.00 1.00 1.00 1.00 1.00 1.00
56.375 1.00 1.00 1.00 1.00 1.00 1.00 61.5 1.00 1.00 1.00 1.00 1.00 1.00 57.75 1.00 1.00 1.00 1.00 1.00 1.00 63 1.00 1.00 1.00 1.00 1.00 1.00
59.125 1.00 1.00 1.00 1.00 1.00 1.00 64.5 1.00 1.00 1.00 60.5 1.00 1.00 1.00 1.00 1.00 1.00 66 1.00 1.00 1.00
61.875 1.00 1.00 1.00 1.00 1.00 1.00 67.5 1.00 1.00 1.00 63.25 1.00 1.00 1.00 1.00 1.00 1.00 69 1.00 1.00 1.00
64.625 1.00 1.00 1.00 70.5 1.00 1.00 1.00 66 1.00 1.00 1.00 72 1.00 1.00 1.00
67.375 1.00 1.00 1.00 73.5 1.00 1.00 1.00 68.75 1.00 1.00 1.00 75 1.00 1.00 1.00
70.125 1.00 1.00 1.00 76.5 1.00 1.00 1.00 71.5 1.00 1.00 1.00 78 1.00 1.00 1.00
72.875 1.00 1.00 1.00 79.5 1.00 1.00 1.00 74.25 1.00 1.00 1.00 81 1.00 1.00 1.00
75.625 1.00 1.00 1.00 77 1.00 1.00 1.00
Table M16.2-7C Solid Sawn Timbers Rating 1-HOUR 1.5-HOUR 2-HOUR
Beam Width 5.5 7.5 9.5 11.5 7.5 9.5 11.5 9.5 11.5 Beam Depth Design Load Ratio, Rs
5.5 0.66 0.75 0.80 0.83 0.17 0.19 0.20 7.5 1.00 1.00 1.00 1.00 0.63 0.70 0.74 0.30 0.32 9.5 1.00 1.00 1.00 1.00 0.90 0.99 1.00 0.64 0.69 11.5 1.00 1.00 1.00 1.00 1.00 1.00 1.00 0.86 0.93 13.5 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 15.5 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 17.5 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 19.5 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 21.5 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 23.5 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
AMERICAN WOOD COUNCIL
154 M16: FIRE DESIGN
Table M16.2-8 Design Load Ratios for Tension Members Exposed on Four Sides (Structural Calculations at Standard Reference Conditions: CD = 1.0, CM = 1.0, Ct = 1.0, Ci = 1.0)
Table M16.2-8A Southern Pine Structural Glued Laminated Timbers
Table M16.2-8B Western Species Structural Glued Laminated Timbers
Rating 1-HOUR 1.5-HOUR 2-HOUR Rating 1-HOUR 1.5-HOUR 2-HOUR Beam Width 5 6.75 8.5 10.5 6.75 8.5 10.5 8.5 10.5 Beam Width 5.125 6.75 8.75 10.75 6.75 8.75 10.75 8.75 10.75 Beam Depth Design Load Ratio, Rs Beam Depth Design Load Ratio, Rs
5.5 0.28 0.46 0.57 0.65 0.07 0.11 0.13 6 0.34 0.53 0.67 0.76 0.12 0.20 0.25 6.875 0.38 0.63 0.78 0.89 0.20 0.32 0.41 0.06 0.09 7.5 0.44 0.69 0.87 0.99 0.24 0.41 0.51 0.12 0.18 8.25 0.45 0.75 0.93 1.00 0.29 0.46 0.59 0.17 0.26 9 0.51 0.80 1.00 1.00 0.33 0.54 0.68 0.23 0.35
9.625 0.50 0.83 1.00 1.00 0.35 0.56 0.72 0.25 0.39 10.5 0.56 0.87 1.00 1.00 0.39 0.64 0.80 0.31 0.47 11 0.54 0.89 1.00 1.00 0.40 0.64 0.81 0.31 0.48 12 0.59 0.93 1.00 1.00 0.43 0.71 0.89 0.37 0.55
12.375 0.57 0.94 1.00 1.00 0.44 0.70 0.89 0.36 0.55 13.5 0.62 0.98 1.00 1.00 0.46 0.77 0.96 0.42 0.62 13.75 0.59 0.98 1.00 1.00 0.47 0.75 0.95 0.39 0.61 15 0.64 1.00 1.00 1.00 0.49 0.81 1.00 0.46 0.68
15.125 0.61 1.00 1.00 1.00 0.49 0.78 1.00 0.42 0.66 16.5 0.66 1.00 1.00 1.00 0.51 0.85 1.00 0.49 0.72 16.5 0.62 1.00 1.00 1.00 0.51 0.82 1.00 0.45 0.70 18 0.68 1.00 1.00 1.00 0.53 0.88 1.00 0.51 0.76
17.875 0.64 1.00 1.00 1.00 0.53 0.84 1.00 0.47 0.73 19.5 0.69 1.00 1.00 1.00 0.55 0.91 1.00 0.53 0.79 19.25 0.65 1.00 1.00 1.00 0.54 0.87 1.00 0.49 0.76 21 0.70 1.00 1.00 1.00 0.56 0.93 1.00 0.55 0.82
20.625 0.66 1.00 1.00 1.00 0.56 0.89 1.00 0.51 0.79 22.5 0.71 1.00 1.00 1.00 0.57 0.95 1.00 0.57 0.84 22 0.67 1.00 1.00 1.00 0.57 0.91 1.00 0.52 0.81 24 0.72 1.00 1.00 1.00 0.58 0.97 1.00 0.58 0.86
23.375 0.68 1.00 1.00 1.00 0.58 0.92 1.00 0.53 0.83 25.5 0.73 1.00 1.00 1.00 0.59 0.98 1.00 0.59 0.88 24.75 0.68 1.00 1.00 1.00 0.59 0.93 1.00 0.54 0.84 27 0.73 1.00 1.00 1.00 0.60 0.99 1.00 0.60 0.90
26.125 0.69 1.00 1.00 1.00 0.60 0.95 1.00 0.55 0.86 28.5 0.74 1.00 1.00 1.00 0.61 1.00 1.00 0.61 0.91 27.5 0.69 1.00 1.00 1.00 0.60 0.96 1.00 0.56 0.87 30 0.75 1.00 1.00 1.00 0.61 1.00 1.00 0.62 0.93
28.875 0.70 1.00 1.00 1.00 0.61 0.97 1.00 0.57 0.89 31.5 0.75 1.00 1.00 1.00 0.62 1.00 1.00 0.63 0.94 30.25 0.70 1.00 1.00 1.00 0.61 0.98 1.00 0.58 0.90 33 0.76 1.00 1.00 1.00 0.62 1.00 1.00 0.64 0.95
31.625 0.71 1.00 1.00 1.00 0.62 0.99 1.00 0.58 0.91 34.5 0.76 1.00 1.00 1.00 0.63 1.00 1.00 0.65 0.96 33 0.71 1.00 1.00 1.00 0.62 0.99 1.00 0.59 0.92 36 0.76 1.00 1.00 1.00 0.63 1.00 1.00 0.65 0.97
34.375 0.71 1.00 1.00 1.00 0.63 1.00 1.00 0.60 0.92 37.5 1.00 1.00 1.00 0.64 1.00 1.00 0.66 0.98 35.75 0.72 1.00 1.00 1.00 0.63 1.00 1.00 0.60 0.93 39 1.00 1.00 1.00 0.64 1.00 1.00 0.66 0.98
37.125 1.00 1.00 1.00 0.64 1.00 1.00 0.61 0.94 40.5 1.00 1.00 1.00 0.65 1.00 1.00 0.67 0.99 38.5 1.00 1.00 1.00 0.64 1.00 1.00 0.61 0.95 42 1.00 1.00 1.00 0.65 1.00 1.00 0.67 1.00
39.875 1.00 1.00 1.00 0.64 1.00 1.00 0.61 0.95 43.5 1.00 1.00 1.00 0.65 1.00 1.00 0.68 1.00 41.25 1.00 1.00 1.00 0.65 1.00 1.00 0.62 0.96 45 1.00 1.00 1.00 0.65 1.00 1.00 0.68 1.00
42.625 1.00 1.00 1.00 0.65 1.00 1.00 0.62 0.97 46.5 1.00 1.00 1.00 0.66 1.00 1.00 0.68 1.00 44 1.00 1.00 1.00 0.65 1.00 1.00 0.62 0.97 48 1.00 1.00 1.00 0.66 1.00 1.00 0.69 1.00
45.375 1.00 1.00 1.00 0.66 1.00 1.00 0.63 0.98 49.5 1.00 1.00 1.00 1.00 0.69 1.00 46.75 1.00 1.00 1.00 0.66 1.00 1.00 0.63 0.98 51 1.00 1.00 1.00 1.00 0.69 1.00
48.125 1.00 1.00 1.00 0.66 1.00 1.00 0.63 0.98 52.5 1.00 1.00 1.00 1.00 0.69 1.00 49.5 1.00 1.00 1.00 1.00 0.64 0.99 54 1.00 1.00 1.00 1.00 0.70 1.00
50.875 1.00 1.00 1.00 1.00 0.64 0.99 55.5 1.00 1.00 1.00 1.00 0.70 1.00 52.25 1.00 1.00 1.00 1.00 0.64 1.00 57 1.00 1.00 1.00 1.00 0.70 1.00
53.625 1.00 1.00 1.00 1.00 0.64 1.00 58.5 1.00 1.00 1.00 1.00 0.70 1.00 55 1.00 1.00 1.00 1.00 0.65 1.00 60 1.00 1.00 1.00 1.00 0.71 1.00
56.375 1.00 1.00 1.00 1.00 0.65 1.00 61.5 1.00 1.00 1.00 1.00 0.71 1.00 57.75 1.00 1.00 1.00 1.00 0.65 1.00 63 1.00 1.00 1.00 1.00 0.71 1.00
59.125 1.00 1.00 1.00 1.00 0.65 1.00 64.5 1.00 1.00 1.00 60.5 1.00 1.00 1.00 1.00 0.65 1.00 66 1.00 1.00 1.00
61.875 1.00 1.00 1.00 1.00 0.65 1.00 67.5 1.00 1.00 1.00 63.25 1.00 1.00 1.00 1.00 0.66 1.00 69 1.00 1.00 1.00
64.625 1.00 1.00 1.00 70.5 1.00 1.00 1.00 66 1.00 1.00 1.00 72 1.00 1.00 1.00
67.375 1.00 1.00 1.00 73.5 1.00 1.00 1.00 68.75 1.00 1.00 1.00 75 1.00 1.00 1.00
70.125 1.00 1.00 1.00 76.5 1.00 1.00 1.00 71.5 1.00 1.00 1.00 78 1.00 1.00 1.00
72.875 1.00 1.00 1.00 79.5 1.00 1.00 1.00 74.25 1.00 1.00 1.00 81 1.00 1.00 1.00
75.625 1.00 1.00 1.00 77 1.00 1.00 1.00
Table M16.2-8C Solid Sawn Timbers Rating 1-HOUR 1.5-HOUR 2-HOUR
Beam Width 5.5 7.5 9.5 11.5 7.5 9.5 11.5 9.5 11.5 Beam Depth Design Load Ratio, Rs
5.5 0.34 0.51 0.61 0.68 0.09 0.12 0.14 7.5 0.51 0.77 0.92 1.00 0.32 0.45 0.54 0.15 0.20 9.5 0.61 0.92 1.00 1.00 0.45 0.64 0.76 0.32 0.43 11.5 0.68 1.00 1.00 1.00 0.54 0.76 0.91 0.43 0.58 13.5 0.72 1.00 1.00 1.00 0.60 0.85 1.00 0.51 0.68 15.5 0.76 1.00 1.00 1.00 0.64 0.91 1.00 0.56 0.76 17.5 0.78 1.00 1.00 1.00 0.68 0.96 1.00 0.61 0.82 19.5 0.80 1.00 1.00 1.00 0.70 1.00 1.00 0.64 0.87 21.5 0.82 1.00 1.00 1.00 0.73 1.00 1.00 0.67 0.91 23.5 0.83 1.00 1.00 1.00 0.75 1.00 1.00 0.70 0.94
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Table M16.2-9 Design Load Ratios for Exposed Timber Decks Double and Single Tongue & Groove Decking
(Structural Calculations at Standard Reference Conditions: CD = 1.0, CM = 1.0, Ct = 1.0, Ci = 1.0)
Table M16.2-10 Design Load Ratios for Exposed Timber Decks Butt-Joint Timber Decking
(Structural Calculations at Standard Reference Conditions: CD = 1.0, CM = 1.0, Ct = 1.0, Ci = 1.0)
Rating 1-HOUR 1.5-HOUR 2-HOUR Deck Thickness Design Load Ratio, Rs
2.5 0.22 - - 3 0.46 0.08 -
3.5 0.67 0.23 0.03 4 0.86 0.40 0.12
4.5 1.00 0.56 0.25 5 1.00 0.71 0.38
5.5 1.00 0.85 0.51
Rating 1-HOUR 1.5-HOUR 2-HOUR Decking Width 1.5 2.5 3.5 5.5 2.5 3.5 5.5 3.5 5.5 Decking Depth Design Load Ratio, Rs
2.5 0.05 0.12 0.15 0.18 - - - - - 3 0.09 0.24 0.30 0.36 0.03 0.04 0.05 - -
3.5 0.14 0.35 0.44 0.53 0.08 0.12 0.16 - - 4 0.18 0.45 0.57 0.68 0.14 0.21 0.28 0.02 0.08
4.5 0.21 0.54 0.68 0.80 0.19 0.30 0.39 0.04 0.16 5 0.24 0.61 0.77 0.92 0.24 0.38 0.50 0.06 0.24
5.5 0.27 0.68 0.85 1.00 0.29 0.45 0.59 0.09 0.32
AMERICAN WOOD COUNCIL
156 M16: FIRE DESIGN
Example 16.2-1 Exposed Beam Example - Allowable Stress Design
unchanged. Therefore, the maximum induced moment is
Calculate beam section modulus exposed on three sides: Sf = (b – 2a)(d – a)2/6 = (6.75 – 3.6)(13.5 – 1.8)2/6 = 71.9 in.3
Calculate the adjusted allowable bending stress (assuming CD = N/A; CM = N/A; Ct = N/A; CL = 1.0; CV b = Fb (lesser of CL or CV) = 2,400 (0.98) = 2,343 psi (NDS 5.3.1)
Calculate strength resisting moment: b Sf = (2.85)(2,343)(71.9)/12
= 40,010 ft-lbs (NDS 16.2.2)
Fire Check: M max
Design Aid Calculate structural design load ratio: rs = Mmax
Select the maximum design load ratio limit from Table M16.2-1B or calculate using the following equation:
R S
S C C Cs f
s D M t
2 85 2 85 71 9 205 1 0 1 0 1 0
1 00 . ( . )( . )
( )( . )( . )( . ) .
Fire Check: Rs s
at s = 6'. The design loads are qlive = 100 psf and qdead = 25 psf. Timber decking nailed to the compression edge of the beams provides lateral bracing. Calculate the required
For the structural design of the wood beam, calculate the maximum induced moment.
Calculate beam load: wtotal = s (qdead + qlive) = (6)(25 + 100) = 750 plf
Calculate maximum induced moment: Mmax = wtotal L²/8 = (750)(18)²/8 = 30,375 ft-lbs
Select a 6-3/4" x 13-1/2" 24F visually-graded Doug- b,
equal to 2,400 psi.
Calculate beam section modulus: Ss = bd2/6 = (6.75)(13.5)2/6 = 205.0 in.3
Calculate the adjusted allowable bending stress (assuming CD = 1.0; CM = 1.0; Ct = 1.0; CL = 1.0; CV = 0.98)
b = Fb (CD)(CM)(Ct)(lesser of CL or CV) = 2,400 (1.0)(1.0)(1.0)(0.98) = 2,343 psi (NDS 5.3.1)
Calculate design resisting moment: b Ss = (2,343)(205.0)/12 = 40,032 ft-lbs
Structural Check: M max
Example 16.2-2 Exposed Column Example - Allowable Stress Design
A southern pine glulam column with an effective col- umn length, e = 168". The design loads are Psnow = 16,000 lbs and Pdead = 6,000 lbs. Calculate the required section
For the structural design of the wood column, calculate the maximum induced compression stress, fc.
Calculate column load: Ptotal = Pdead + Psnow = 8,000 + 16,000 = 22,000 lbs
Select a 8-1/2" x 9-5/8" Combination #48 southern pine glulam column with a tabulated compression paral- lel-to-grain stress, Fc, equal to 2,200 psi and a tabulated modulus of elasticity, Emin, equal to 880,000 psi.
Calculate column area: As = bd = (9.625)(8.5) = 81.81 in.2 Is = bd3/12 = (9.625)(8.5)3/12 = 492.6 in.4
Calculate the adjusted allowable compression stress (assuming CD = 1.15; CM = 1.0; Ct = 1.0): Emin min (CM)(Ct) = 880,000 (1.0)(1.0) = 880,000 psi (NDS 5.3.1)
FcE = 0.822 Emin e/d)2 = 0.822 (880,000) / (168/8.5)2 = 1,852 psi (NDS 3.7.1.5)
F*c = Fc (CD)(CM)(Ct) = 2,200 (1.15)(1.0)(1.0) = 2,530 psi (NDS 3.7.1.5)
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c = 0.9 for structural glued laminated timbers (NDS 3.7.1.5)
C c c cP
c c c1 2
1 2
1 0 7190 2 0 9
2 F /F F /F F /FcE cE cE
* * *
. ( . )
11 0 7190 2 0 9
0 7190 0 9
0 626
2 .
( . ) .
.
.
(NDS 3.7.1.5)
c = Fc* (Cp) = 2,530 (0.626) = 1,583 psi (NDS 5.3.1)
Calculate the resisting column compression capacity: c As = (1,583)(81.81) = 129,469 lbs
Pload 129,469 lbs 22,000 lbs OK
is unchanged. Therefore, the total load is unchanged. The
Calculate column area, A, and moment of inertia, I, for column exposed on four sides: Af = (b – 2a)(d – 2a) = (9.625 – 3.6)(8.5 – 3.6) = 29.52 in.2 If = (b – 2a)(d – 2a)3/12 = (9.625 – 3.6)(8.5 – 3.6)3/12 = 59.07 in.4 Calculate the adjusted allowable compression stress (assuming CD = N/A; CM = N/A; Ct = N/A):
FcE = (2.03) 0.822 Emin e/d)2 = (2.03)(0.822)(880,000) / (168/(8.5 – 3.6))2 = 1,249 psi ft-lbs (NDS 16.2.2)
F*c = (2.58) Fc = (2.58)(2,200) = 5,676 psi ft-lbs (NDS 16.2.2) FcE/F*c = 1,249/5,676 = 0.22
CP 1 0 22 2 0 9
1 0 22 2 0 9
0 22 0 9
0 214 2
. ( . )
. ( . )
. .
.
c = 5,676 (0.214) = 1,216 psi
Calculate the resisting column compression capacity: c Af = (1,216)(29.52) = 35,884 lbs
load
Design Aid Calculate structural design load ratio: rs = Mmax
Select the maximum design load ratio (buckling) limit from Table M16.2-5A or calculate using the following equation:
R I
I C Cs f
s M t
2 03 2 03 59 07 492 6 1 0 1 0
0 24 . ( . )( . )
( . )( . )( . ) .
Fire Check: Rs s
Example 16.2-3 Exposed Tension Member Example - Allowable Stress Design
Solid sawn Hem-Fir timbers used as heavy timber truss webs. The total design tension loads from a roof live and dead load are Ptotal = 3,500 lbs. Calculate the required
For the structural design of the wood timber, calculate the maximum induced tension stress, ft.
Calculate tension load: Ptotal = 3,500 lbs
Select a nominal 6x6 (5-1/2" x 5-1/2") Hem-Fir #2 Posts and Timbers grade with a tabulated tension stress, Ft, equal to 375 psi. Calculate timber area: As = bd = (5.5)(5.5) = 30.25 in.2
Calculate the adjusted allowable tension stress (assuming CD = 1.25; CM = 1.0; Ct = 1.0):
t = Ft (CD)(CM)(Ct) = 375 (1.25)(1.0)(1.0) = 469 psi (NDS 4.3.1)
Calculate the resisting tension capacity: c As = (469)(30.25) = 13,038 lbs
load
AMERICAN WOOD COUNCIL
158 M16: FIRE DESIGN
the loading is unchanged. Therefore, the total load is un-
Calculate tension member area, A, for member exposed on four sides: Af = (b – 2a)(d – 2a) = (5.5 – 3.6)(5.5 – 3.6) = 3.61 in.2
Calculate the adjusted allowable tension stress (assuming CD = N/A; CM = N/A; Ct = N/A):
t = (2.85) Ft = (2.85)(375) = 1,069 psi ft-lbs (NDS 16.2.2)
Calculate the resisting tension capacity: t Af = (1,069)(3.61) = 3,858 lbs
load
unchanged. Therefore, the maximum induced moment is
Calculate beam section modulus exposed on one side: Sf = (b)(d – a)2/6 = (5.5)(2.5 – 1.8)2/6 = 0.45 in.3
Calculate the adjusted allowable bending stress (assuming CD = N/A; CM = N/A; Ct = N/A; CF = 1.04):
b = Fb (CF) = 1,350 (1.04) = 1,404 psi
Calculate resisting moment: b Sf = (2.85)(1,404)(0.45)/12
= 150 ft-lbs (NDS 16.2.2)
max
Design Aid Calculate structural design load ratio: rs = Mmax
Select the maximum design load ratio limit from Table M16.2-9 or calculate using the following equation:
R S
S C C Cs f
s D M t
2 85 2 85 0 45 5 73 1 0 1 0 1 0
0 22 . ( . )( . )
( . )( . )( . )( . ) .
Fire Check: Rs s
Design Aid Calculate structural design load ratio: rs = Mmax
Select the maximum design load ratio limit from Table M16.2-8C and divide by the load duration factor, CD, or calculate using the following equation:
R A
A C C Cs f
s D M t
2 85 2 85 3 61 30 25 1 25 1 0 1 0
0 27 . ( . )( . )
( . )( . )( . )( . ) .
Fire Check: Rs s
Example 16.2-4 Exposed Deck Example - Allowable Stress Design
Hem-Fir tongue-and-groove timber decking spans
the decking. The design loads are qlive = 40 psf and qdead = 10 psf.
Calculate deck load: wtotal = B(qdead + qlive) = (5.5 in./12 in./ft)(50 psf) = 22.9 plf
Calculate maximum induced moment: Mmax = wtotal L²/8 = (22.9)(6)²/8 = 103 ft-lbs
Select nominal 3x6 (2-1/2" x 5-1/2") Hem-Fir Com- mercial decking with a tabulated bending stress, Fb, equal to 1,350 psi (already adjusted by Cr).
Calculate beam section modulus: Ss = bd2/6 = (5.5)(2.5)2/6 = 5.73 in.3
Calculate the adjusted allowable bending stress (assuming CD = 1.0; CM = 1.0; Ct = 1.0; CF = 1.04):
b = Fb (CD)(CM)(Ct)(CF) = 1,350 (1.0)(1.0)(1.0)(1.04) = 1,404 psi (NDS 4.3.1)
Calculate resisting moment: b Ss = (1,404)(5.73)/12 = 670 ft-lbs
Mmax
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M16.3 Wood Connections
for a 1-hour rating. Typical details for commonly used fasteners and connectors in timber framing are shown in Figure M16.3-1 through Figure M16.3-6.
Figure M16.3-1 Beam to Column Connection - Connection Not Exposed to Fire
Figure M16.3-2 Beam to Column Connection - Connection Exposed to Fire Where Appearance is a Factor
Figure M16.3-3 Ceiling Construction
Figure M16.3-4 Beam to Column Connection - Connection Exposed to Fire Where Appearance is Not a Factor
AMERICAN WOOD COUNCIL
160 M16: FIRE DESIGN
Figure M16.3-5 Column Connections Covered
Figure M16.3-6 Beam to Girder - Concealed Connection
American Wood Council Engineered and Traditional Wood Products
AWC Mission Statement To increase the use of wood by assuring the broad regulatory acceptance of wood products, developing design tools and guidelines for wood construction,
affecting the use of wood products.
09-08
American Forest & Paper Association American Wood Council 1111 19th Street, NW Suite 800 Washington, DC 20036 www.awc.org [email protected]
America’s Forest & Paper People ® Improving Tomorrow’s Environment Today®
- ASD/LRFD Manual of Engineered Wood Construction
- Title
- Foreword
- Table Of Contents
- List Of Tables
- List Of Figures
- M1: General Requirements For Structural Design
- M1.1 Products Covered In This Manual
- M1.2 General Requirements
- M1.3 Design Procedures
- M2: Design Values For Structural Members
- M2.1 General Information
- M2.2 Reference Design Values
- M2.3 Adjustment Of Design Values
- M3: Design Provisions And Equations
- M3.1 General
- M3.2 Bending Members - General
- M3.3 Bending Members - Flexure
- M3.4 Bending Members - Shear
- M3.5 Bending Members - Deflection
- M3.6 Compression Members
- M3.7 Solid Columns
- M3.8 Tension Members
- M3.9 Combined Bending And Axial Loading
- M3.10 Design For Bearing
- M4: Sawn Lumber
- M4.1 General
- M4.2 Reference Design Values
- M4.3 Adjustment Of Reference Design Values
- M4.4 Special Design Considerations
- M4.5 Member Selection Tables
- M4.6 Examples Of Capacity Table Development
- M5: Structural Glued Laminated Timber
- M5.1 General
- M5.2 Reference Design Values
- M5.3 Adjustment Of Reference Design Values
- M5.4 Special Design Considerations
- M6: Round Timber Poles And Piles
- M6.1 General
- M6.2 Reference Design Values
- M6.3 Adjustment Of Reference Design Values
- M6.4 Special Design Considerations
- M7: Prefabricated Wood I- Joists
- M7.1 General
- M7.2 Reference Design Values
- M7.3 Adjustment Of Reference Design Values
- M7.4 Special Design Considerations
- M8: Structural Composite Lumber
- M8.1 General
- M8.2 Reference Design Values
- M8.3 Adjustment Of Reference Design Values
- M8.4 Special Design Considerations
- M9: Wood Structural Panels
- M9.1 General
- M9.2 Reference Design Values
- M9.3 Adjustment Of Reference Design Values
- M9.4 Special Design Considerations
- M10: Mechanical Connections
- M10.1 General
- M10.2 Reference Design Values
- M10.3 Design Adjustment Factors
- M10.4 Typical Connection Details
- M10.5 Pre- Engineered Metal Connectors
- M11: Dowel-type Fasteners
- M11.1 General
- M11.2 Reference Withdrawal Design Values
- M11.3 Reference Lateral Design Values
- M11.4 Combined Lateral And Withdrawal Loads
- M11.5 Adjustment Of Reference Design Values
- M11.6 Multiple Fasteners
- M12: Split Ring And Shear Plate Connectors
- M12.1 General
- M12.2 Reference Design Values
- M12.3 Placement Of Split Ring And Shear Plate Connectors
- M13: Timber Rivets
- M13.1 General
- M13.2 Reference Design Values
- M13.3 Placement Of Timber Rivets
- M14: Shear Walls And Diaphragms
- M14.1 General
- M14.2 Design Principles
- M14.3 Shear Walls
- M14.4 Diaphragms
- M15: Special Loading Conditions
- M15.1 Lateral Distribution Of Concentrated Loads
- M15.2 Spaced Columns
- M15.3 Built- Up Columns
- M15.4 Wood Columns With Side Loads And Eccentricity
- M16: Fire Design
- M16.1 General
- Lumber
- Structural Glued Laminated Timber
- Poles And Piles
- Structural Composite Lumber
- Wood I- Joists
- Metal Plate Connected Wood Trusses
- M16.2 Design Procedures For Exposed Wood Members
- M16.3 Wood Connections