Engr 426 steel structure A

ENGR 426 - Spring 2020 San Francisco State University Instructor: S. Günay

Homework 7 (Due: 4/28/2020) Question 1 Consider a W14×500, A992 42 ft column in a braced frame with a compressive dead load (PD) of 90 kips and live load (PL) of 270 kips as shown in the figure below. Maintaining a live load to dead load ratio of 3, using LRFD and considering that the lower end is pinned, determine the maximum live and dead moments that can be applied about the strong axis at the upper end. Assume Kx=Ky=1 and use the correct Cb.

Question 2 Determine by LRFD whether a W14×48, A992 member is adequate for use as a 14 ft column in a moment frame. The frame is designed so that under a lateral load H=50 kips, the frame drifts no more than L/300. The total story load, Pstory is 1,360 kips. Analysis results from a first order analysis for no-translation and translation cases are shown below. The column is bending about the strong axis. Assume Kx=Ky=1, use the correct Cb and consider all columns are part of the lateral load resisting system.

Pnt = 85.0 kips

Mnt = 112.0 kip-ft

Pnt = 85.0 kips

Mnt = 112.0 kip-ft

Plt = 85.0 kips

Plt = 85.0 kips

Mlt = 92.0 kip-ft

Mlt = 92.0 kip-ft