write me conclusion

The site currently houses University Place Hotel and Conference Center. According to Jason Franklin, Director of PSU Campus Planning and Design, the hotel is significantly larger than existing demand. A new concept of the site seeks to optimize its workability. The Livework Model has a higher concentration of uses, and is oriented around green spaces. The design also incorporates a vehicular surface street through the parcel, facilitating access to the site. Residential buildings may be market-rate apartments, or student or active senior housing. Finally, the design also incorporates a low-cost incubator office structure in the northwest corner, which has possible synergy with similar buildings across 4th Avenue.

The existing structure began as a hotel owned by Red Lion, and was built in the 1960s “as part of an urban renewal and redevelopment plan” (University Place Hotel, 2015). The hotel opened as University Place Hotel and Conference Center in 2004, when Portland State University acquired the property. Since the 1960s, the city’s population has nearly doubled (Figure 2), increasing the demand for urban space (US Census Bureau, 2014). As urban development increases in downtown Portland, space becomes a more valuable resource. The University Place parcel has the potential to accommodate a significantly higher density of residents upon redevelopment.

Figure 4: Population versus year in Portland, OR

Portland has warm, dry summers and cool, rainy winters, receiving an average of 38 inches of rain annually. With the site being nearly four acres in size, stormwater runoff needs to be addressed in the design. The client is particularly interested in harvesting rainwater and potentially incorporating a decentralized waste water treatment system into the design. Decreasing the environmental impact of the site redevelopment is among the goals of PSU for this project.

Traffic access to the site is also an area of concern. The current site has entrances and exits at both the northeast and northwest sides of the site along Lincoln Street, with parking spaces surrounding the existing building (Figure 5). The entrances are accessible to the northbound, 4th Avenue traffic via right turn, and to eastbound traffic on SW Lincoln Street. Access is limited due to the max line located on SW Lincoln Street, which divides eastbound and westbound traffic along the street. The final goal of the redevelopment project is to modify traffic flow in a way that facilitates access to the site and prevents congestion.

The geology in downtown Portland consists of mostly clays and silts, which have very low permeability (US Department of Agriculture, 2002). These soils are challenging to work with when attempting to decrease stormwater runoff, as the soils absorb little water during a storm event. Because the site will be largely impervious after development, options such as rainwater harvesting should be considered for a sustainable design.

An alternatives analysis was completed for each major component of the project. The purpose of each analysis is to rank all viable options to arrive at the best choice. The following sections summarize ranking criteria and results for each considered alternative.

This section outlines the considered alternatives for transportation design, including the layouts of the site entrance and exit, parking spaces, and a ground level access road.

Traffic circulation to and from the project site is an area of concern due to the complex traffic layout surrounding the area. At the east entrance/exit, the allowable movements include northbound through, right turn, left turn, south bound through, left turn, right turn, east bound through, left turn, right turn, U-turn, and west bound through, left turn, right turn, and U-turn. The proposed Livework model relocates parking to a two-tier, underground, parking structure. To accommodate underground parking, five different light configurations which modify traffic flow were analyzed. The current west entrance/exit will be constructed into an entrance only, while the east entrance/exit will be an exit only. This will allow for one-way traffic flow within the parking structure. With the traffic entering the site from the west and leaving the site from the east exit, the traffic flow will be more easily controlled to prevent congestion on SW Lincoln Street.

To simplify traffic access to the site, the following traffic signal layouts for the northeast entrance and exit were considered:

· Option 1: No build (Figure 6)

· Option 2: Northbound through/ right-turn, left-turn (Figure 7)

· Option 3: Northbound right turn, eastbound left turn/right turn, westbound right turn (Figure 8)

· Option 4: Right turn only (Figure 9)

· Option 5: Northbound right turn, southbound right turn, eastbound U-turn, westbound U-turn (Figure 10)

The five traffic signal configurations were scored on the following criteria: cost, effectiveness, maintainability, and design schedule (Table 1). Effectiveness was scored out of a possible ten points while the other three categories were scored out of a possible five points. Effectiveness is weighted the highest because this criteria will ultimately decide if the traffic signal configuration can handle the expected traffic flow without causing congestion. Each traffic signal will be analyzed using Synchro or PTV Vissim (to be completed at a later iteration of report).

CE 484 50% Design Report Group 15

1 | Page

Based on the decision matrix, Portland Consulting Engineers propose Option 2 (Northbound through, right turn, left turn). Option 2 is the most economic choice that can still handle the expected increase in traffic flow. The cost is based on the alterations that would have to be made to the current traffic signal system. From the U.S. Department of Transportation, the cost of updating the traffic signal costs between $2,500 and $3,100 per signal per update (City of Rockville, 2010). Additionally, for a 5 section LED traffic signal housing, the cost per signal is $1,600 (City of Rockville, 2010). For option 2, the estimated cost of material and signal update is about $14,000 (excluding labor).

Two alternatives were considered for the parking structure layout, including layouts with parking at a 45 degree angle and at a 90 degree angle. For sites with low to moderate turnover visitor spaces, the recommended width of the stall is eight feet, six inches with twenty inch door clearance between stalls (The Dimensions of Parking, 2000). This recommendation applies to both alternatives. Stalls angled at 90 degrees must have a depth of seventeen feet, eight inches and aisles must be twenty four feet wide when using double-loaded isles for one-way traffic (ideal to maximize parking capacity). For stalls angled at 90 degrees, the stall depth must be eighteen feet and aisle width can be reduced to twelve feet, eight inches (The Dimensions of Parking, 2000).

The structure will have a total of seven hundred spaces between the two floors. To comply with the Americans with Disabilities Act (ADA), two percent of the parking spaces must be accessible spaces (The Dimensions of Parking, 2000). Therefore, the structure must include a minimum of fourteen accessible spaces, including at least one van-accessible space. For a standard accessible parking space, the width of the stall is eight feet with a five foot wide demarcated accessible aisle next to it. When using 90 degree angles spots, two accessible spaces may share the same accessible aisle. When using angled parking, accessible aisles may not be shared (Washington DC: Urban Land Institute, 2000).

The proposed design is primarily 45 degree, doubly-loaded aisles for one-way traffic. In the structure, two elevators must be used to accommodate users of the hotel and housing units. To utilize the area where the elevators are located, the required accessible spaces will be 90 degrees in order for accessible aisles to be shared. This layout is consistent between both the ground level and basement level floor. Spaces located on the west side of the structure for both floors will be short term spaces for market use only.

For the street passing through the site, two alternatives were considered, including a pedestrian and vehicle shared street, and a pedestrian-only street. A shared street must be constructed to a width that satisfies the fire code. This option includes multiple short term parking spots, located near retail locations. The pedestrian-only street also provides access to emergency vehicles, but does not accommodate temporary parking spots. To maximize space, the most feasible alternative is a pedestrian-only street with emergency vehicle access. This design regulates the flow of traffic in the site by requiring all vehicles enter and exit through the parking structure. This option also provide more potential greenspace areas in place of the small, ground level parking lots.

Underground structures are generally made of a combination of steel and concrete. For the design of the underground parking garage, the following alternatives were considered:

· Option 1: No build

· Option 2: Reinforced Concrete

· Option 3: Post-tensioned concrete

· Option 4: Steel

Option 1 (no build) considers the current parking lot layout. This layout accommodates approximately 200 vehicles at ground level. The parking area surrounds the existing building. Options two and three consider two types of concrete and steel combinations: reinforced and post-tensioned concrete. Both types of concrete utilize steel to increase the flexural strength of concrete. However, reinforced concrete incorporates rebar whereas post-tensioned concrete incorporates tensioned cables. Both materials are also common for underground parking structures. Finally, option four (steel) has a relatively high strength-to-weight ratio, which may bring the cost of the structure down. Tables 3 and 4 summarize the criteria and scoring for each of the four alternatives. Table 2 shows the alternatives analysis matrix for these options.

Reinforced concrete is slightly less economical than post-tensioned concrete for long slab and beam spans (Cross, n.d.). Long spans reduce the number of required columns, which decreases material and labor costs. Steel has a high strength-to-weight ratio, which decreases the amount of material needed. However, the high cost of steel makes this alternative unattractive. Furthermore, the high corrosiveness of steel makes the material unsuitable for underground buildings. Ultimately, the design schedule for reinforced concrete makes it the optimal alternative for the parking structure.

The footprint of the underground parking garage is approximately three acres in size. The most common types of lateral foundation system for underground structures of similar sizes involve reinforced concrete, as they can effectively be designed to bear both lateral and gravity loads. Diaphragm slurry walls are a special type of reinforced concrete walls that effectively resist water penetration; as such, these walls are ideal for structures built below a water table (Figure 10). Based on the geotechnical report completed for the site for the existing hotel, no water table exists below the site for at least 30 feet below the surface, which is approximately the depth of the parking structure (Parking Structures: Recommended Practice for Design and Construction, 1997). For this reason, the most efficient lateral foundation system for the site are standard reinforced concrete walls. The walls will also bear gravity loads. The gravity loads are expected to be significantly larger than the lateral soil pressure. Therefore the amount of reinforcement will most likely be controlled by the gravity loads.

Common choices for structural foundations include deep and concrete mat foundations. Deep foundations (Figure 11) involve driving piles into deep rock layers whereas concrete mat foundations (Figure 12) are relatively shallow and involve a mat of steel reinforcement. The load capacity of the soil at the site is approximately 2.0 kips per square foot (Shannon and Wilson, Inc). Preliminary calculations indicate that this capacity is adequate to support the structure’s gravity loads Therefore both alternatives are considered.

Table 3 shows the ranking for each foundation type based on the following criteria: constructability, construction cost, efficiency, and design schedule. The construction of concrete mat foundations is less complex than the construction of pile foundations. Pile foundations require extensive geotechnical research for design purposes and expensive machinery (pile drivers) during construction. Deep foundations are also the most expensive type of foundation system. Therefore, deep piles rate lower than concrete mats in both constructability and construction cost. The soil load capacity is sufficient to reliably carry the gravity loads of the structural system, and piles have significantly higher load capacities, as they are anchored in rock. Therefore, each foundation alternative can effectively carry the structural loads and thus rate highly in efficiency. The design of mat foundations is relatively complex, as the amount of reinforcement can vary throughout the area of the mat. On design schedule, piles rate better than concrete mats.

Based on these criteria, a concrete mat foundation is the optimal alternative. Although this alternative rates low in design schedule, the time investment is balanced by the savings in cost and constructability. The selection of a foundation type will be finalized after conducting a full structural analysis (in a later iteration of this report).

Stormwater routing is an area of concern because the site, covering approximately four acres, is largely impervious. The lack of pervious surfaces results in high volumes of water runoff during storm events. To address this issue, the following options were considered:

· Living Machine- an ecological stormwater treatment system; treated water is safe for non-potable uses

· Bio Reactor Membrane System- a decentralized wastewater treatment system, capable of treating both stormwater and wastewater; produces clean water that is safe to consume

· Green roof- a roof garden with soil and plants that absorb significant amounts of stormwater; excess water is rerouted to the sewer system

· No Build- this option refers to no construction beyond the minimum requirement by the City of Portland; requirements include stormwater inlets and pipes connecting to the municipal sewage system.

Table 4 shows the ranking of each option, based on sustainability, cost, maintenance, aesthetics, and client preference. Because sustainable infrastructure is among the most critical objectives of this project, sustainability scores are weighed higher. Based on the decision matrix, the best alternative of the four options is the Living Machine.

To satisfy the fire code, the width of the street running through the site will be twenty-four feet wide and have a downward two percent grade with a center ground to disperse surface water (Russ, 2002). The sidewalk will be six feet wide to allocate two-way pedestrian travel. Connecting the street and sidewalk will be connected with a curb and gutter system. The curb will have a height of three quarters of a foot and the gutter will have a negative six percent slope.

Parking Layout

The parking structure layout incorporates double-loaded aisles for one-way traffic, with the spaces angled at 45 degrees. As compared to the layout incorporating 90 degree angled space, this option reduces aisle widths by 11’2”. Therefore, this option is ideal in maximizing usable space. To accommodate the two elevators that will be used by the hotel and the northern housing building, the accessible spaces will be placed adjacent to each elevator. For market users, reserved, short-term spaces will be provided at both the northern and western area of the structure. The next phase of the layout design establishes traffic circulation within the structure. Resources include PCI Parking Structures: Recommended Practice for Design and Construction and 2010 ADA Standards for Accessible Design.

Structural Design

The structural design of the parking structure is largely dependent on the live and dead loads of the structures that lay above. Figure 3 shows a three-dimensional view of the buildings to be built on the University Place parcel. Figure 4 shows a plan view of the footprint of the underground parking structure. The parking structure supports most of the buildings on the parcel. The live load was calculated for each building based on ASCE 7-10: Minimum Design Loads for Buildings and Other Structures. According to ASCE 7-10, the minimum service live load of a residential building is 40 pounds per square foot for each floor. Table 5 shows the service live loads required for each building.

To determine the service loads for the parking structure, the buildings were assumed to be primarily concrete buildings. The parking structure design satisfies ACI 318-11: Building Code Requirements for Structural Concrete, 2012 International Building Code, and 2004 Oregon Structural Specialty Code.

Foundation Design

A geotechnical site investigation is crucial in determining the soil strength capacity at the site. The last geotechnical investigation of the site was performed by Shannon and Wilson Incorporated Soil and Foundation Engineers in October 14, 1968. The report includes four boring logs, each covering a depth of 19 feet, and gives the following recommendations:

-bearing walls should be founded on three feet deep spread footings for the foundation system

-the soil pressure should not exceed 2000 pounds per square foot

The proposed parking structure supports significantly larger loads than the existing hotel building. Additionally, the depth of the structure’s foundation is well below the maximum bored depth of 19 feet in the geotechnical investigation. However, the consistency in the soil profile from the ground surface to 19 feet in depth suggests that the profile continues in pattern for several feet below the depth of 19 feet.

As recommended by the geotechnical firm, footings for the 14 inch square columns are three feet in depth. To meet flexural reinforcement code specifications 11.32 and 11.33, as set by American Concrete Institute (ACI) 318-11, one No. 8 steel bar must be incorporated for every square foot of footing. The foundation slab is 14 inches thick, and column spacing is 30.5 in lengths and 26.5 feet in width, on center.

A later iteration of the report will include details for temporal reinforcement (reinforcement in the lateral direction) and refined footing designs for non-standard columns in the structure.

Based on space calculations (Figure 18) and people occupation for the Office Building, about 350 people would be working daily, having a water use range between 7000 to 12250 gallons of water per day. The living machine for the University Place area would be smaller than the Port of Portland Living Machine, having a 9,000 gallon storage tank to keep all treated water.

Figure 17 - Space Calculator (from Rare Space website)

Using the online tool Rare Space to estimate how many office rooms the university-focused flexible office workspace, it was possible to determine how many people would be circulating in the building during week days. By determining the number of people who would be working in the building, it is possible to estimate the water use per person per day. According to Cushman (2014), recent research about water consumption was made by United States Environmental Protection Agency (EPA). Figure 20 and Table 6 show how much water is consumed per day and how this water is consumed which determines the size of the storage tank.

Figure 18 Water Consumption in Office Buildings (US Environmental Protection Agency)

Figure 19: Water Use Calculator for the Office Building

Although the Living Machine treatment process is feasible for the site area, issues may arise. For example, expensive initial investment and monthly maintenance, and a complex technology to be solved if any part of the system stops working correctly. According to the Port of Portland Engineer Dan Gilkison, a $600,000 initial investment was made to build the Living Machine, plus an additional $11,000 maintenance cost per month.

Portland Consulting Engineers discussed the addition of an ecological sewage treatment system to recycle stormwater and treat sewage on site. A Living Machine is a branded wastewater treatment system that incorporates processes of conventional biological treatment systems, like sedimentation, filtration, nitrification, and denitrification, without the use of chemicals. Based on the alternatives analysis for stormwater routing outlined earlier, Portland Consulting Engineers determined that a Living Machine design is the best option for waste water treatment at the site. Harvesting rainwater and recycling “black water” (sewage) on site decreases the environmental impact of the high-density development, which is consistent with the values of Portland State University. Additionally, the system can serve as an educational tool for university students and provide the community with a better understanding of sustainable water infrastructure.

Figure 20 shows the water cycle of the Living Machine treatment system. The system incorporates living organisms, including plants, snails, fish, and bacteria to remove pollutants and deactivate pathogens from wastewater. In Stage 1, sewage enters an anaerobic tank, where bacteria destroy organic matter and solids settle out of the water. The solids (referred to as sludge) can be used as fertilizer for agricultural needs. In Stages 2 and 3, the water moves through the ecological system where organisms act as a filter and suppress bacterial growth. Stages 4 and 5 purify the water further with additional filtration and UV light sterilization. The water treatment demand of the student housing building will dictate the required volumes of each tank.

To conclude, the cost and space required would be the biggest issue when thinking about the Living Machine construction. Because Portland is located in temperate climate area, a greenhouse or internal space is required to keep the plants and other organisms alive during the cold weather, which increases the price. The maintenance of the Living Machine might not be very expensive, depending on how the system is integrated.

(Section to be completed at later iteration of report)

The chosen traffic signal configuration was Option 2. This was an economical choice that could theoretically handle the flow of traffic from the site. Using the Institution of Traffic Engineers (ITE) Trip Generation Manuel, traffic estimations will be made for the site and will be analyzed using either Synchro or PTV Vissim.

Year

Population

Capacity:350 occupants

Water Use7000gal/dayminimum

12250gal/daymaximum

9625gal/dayAverage

48125gal/weekAverage

2502500gal/yearAverage

Stormwater3995gal/monthNovember (rainiest month)

25532gal/year

Capacity Demands

Stormwater

999gal/week

Black water

55344gal/week

TOTAL56343gal/week

Water Use Calculator