Construction SliDeRulE Case Studies

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1 2015 Construction SliDeRulE Case Studies John Gambatese and Chukwuma Nnaji Oregon State University 2/15/2015

2 1 Construction SliDeRulE Case Studies Case Study #1: Lonnie Harris Black Cultural Center (LHBCC) The Lonnie B. Harris Black Cultural Center is located within the campus of Oregon State University in Corvallis, OR. The 3,400 square feet, one story building is designed to house student gatherings and meetings, and facilitate collaboration amongst students. Rooms available in the facility include: meeting rooms, conference rooms, offices, a kitchen, and a study/relaxation area. Construction of the building, which will cost $2.4 million, started in September 2014 and is expected to finish in spring The facility is depicted in Figure 1.1. Figure 1.1: Architectural Drawing of LHBCC The LHBCC was designed to meet the requirements of a USGBC Leadership in Energy and Environmental Design (LEED) certification. The structure, which primarily consists of a timber frame and concrete masonry exterior, has a strip and spread footings for the walls and columns, respectively. The roofing consists of a combination of low slope modified bitumen membrane on deck and an asphalt shingle roofing system. The building skin consists of brick veneer curtain exterior walls, vinyl clad wood framed windows, and wood trim. Two design elements were selected for analysis on this case study building: the exterior skin and the below grade piping. Analyses of each of these design elements along with alternative design elements are provided below. 1

3 2 Construction SliDeRulE Case Studies Exterior Enclosure: Exterior Skin The building skin on the LHBCC was designed using a brick veneer curtain wall connected to a steel and wood stud back up wall. Figure 1.2 shows an example of a brick veneer curtain wall attached to a steel stud back up wall. Figure 1.2: Example Brick Veneer Curtain Wall with Steel Studs ( The construction activities that are typically undertaken to construct the brick veneer with exterior insulation are listed in Table 1.1 along with the risk factors associated with each activity from the SliDeRulE website. The unit of measure for the brick veneer wall is square feet (SF). Assuming a typical work crew, construction of the veneer requires approximately worker hours per unit to conduct all of the required activities. 2

4 3 Construction SliDeRulE Case Studies Table 1.1: Activities and Risk Factors for Brick Veneer Curtain Wall Act. Unit Risk Factor Cumulative Risk Factor Construction Activities No. (Severity/W hr) (Severity/SF) 1 Installation of exterior sheathing to stud assembly 2 Bolting of steel shelf angle to spandrel beam 3 Installation of scaffold Installation of flashing Installation of air/moisture/vapor barrier Installation of rigid insulation Installation of anchors for brick veneer and back up wall connection 8 Construction of brick veneer Sealing of joints Brick washing Total For this design element, a glass and aluminum curtain wall stick built system was considered as a possible alternative for the building skin. Table 1.2 shows the construction activities and risk factors for this alternative design. The unit of measure is the same as that for brick veneer (SF). Assuming a typical work crew, construction of the glass and aluminum curtain wall requires approximately worker hours per unit. Table 1.2: Activities and Risk Factors for Glass and Aluminum Curtain Wall Act. Unit Risk Factor Cumulative Risk Factor Construction Activities No. (Severity/W hr) (Severity/SF) 1 Installation of mullion anchors to building frame 2 Installation of vertical mullion members, expansion splice, and accessories 3 Installation of horizontal rails between the mullions 4 Installation of spandrel glass/panels to the mullion framework 5 Installation of vision glass panes to the mullion framework Total A quantity take off of the building design drawings was performed to calculate the amount of curtain wall on the building. There is 3,485 square feet of exterior skin on the building. This quantity was then input into SliDeRulE to determine the safety risk value associated with each design element. The results are shown in Table 1.3. The alternative design using a glass and 3

5 4 Construction SliDeRulE Case Studies aluminum curtain wall system was found to have a lower safety risk value. The difference in risk is primarily due to reduced exposures associated with erecting scaffolding, installing the structural support elements, and then placing and washing the aluminum. Table 1.3: Comparison of As Built and Alternative Exterior Curtain Wall Systems Design Design Element Cumulative Total Risk Factor Quantity Design Risk (Severity/SF) As built Brick veneer curtain wall with steel ,485 SF and wood stud back up wall Alternative Glass and aluminum curtain wall stick built system ,485 SF

6 5 Construction SliDeRulE Case Studies Plumbing: Foundation Piping (Below Grade) The LHBCC building is designed with piping below grade to transport sanitary waste and storm water. The design of the piping utilizes thermoplastic pipe (Polyvinyl Chloride, PVC). For sanitary waste the piping runs from inside the building down through the first floor slab and through the foundation to the City s sewer line. Figures 1.3 and 1.4 show the as built piping in several different locations on the project before and after the slab is poured. Figure 1.3: PVC Piping at Foundation prior to Casting Slab Concrete Figure 1.4: PVC Piping at Foundation after Casting Slab Concrete The construction activities that are typically undertaken to install the PVC piping are listed in Table 1.4 along with the risk factors associated with each activity from the SliDeRulE website. The list of activities assumes that the work will be conducted before the foundation forms are in place and the concrete is poured. The unit of measure for the piping is linear feet (LF) of 5

7 6 Construction SliDeRulE Case Studies piping. Each hangar is counted individually and the unit of measure for the hangers is each hanger. Assuming a typical crew, installation of the piping requires approximately worker hours per LF, and installation of the pipe hangers requires approximately workerhours per hanger. Table 1.4: Activities and Risk Factors for PVC Piping under Foundation Act. Unit Risk Factor Cumulative Risk Factor Construction Activities No. (Severity/W hr) (Severity/Unit) 1 Transport pipe to location of installation Transport hangers* Hanger installation* Spool fabrication Pipe placement and connection Functional test of pipe Seal penetrations Pipe labeling Total (pipe) *Total (hangers) A cast iron piping system was selected as a possible alternative to using PVC piping. Table 1.5 shows the construction activities and risk factors for cast iron piping. Assuming a typical crew, installation of the piping requires approximately worker hours per LF, and installation of the pipe hangers is the same at that for PVC piping (1.440 worker hours per hanger). Table 1.5: Activities and Risk Factors for Cast Iron Piping under Foundation Act. Unit Risk Factor Cumulative Risk Factor Construction Activities No. (Severity/W hr) (Severity/Unit) 1 Transport pipe to location of installation Transport hangers* Hanger installation* Pipe placement and connection Functional test of pipe Seal penetrations Pipe labeling Total (pipe) *Total (hangers) A quantity take off of the foundation piping showed that approximately 346 linear feet of PVC piping is used in the building according to the as built design. This amount of pipe is the same for both PVC piping and cast iron piping. This quantity was then entered into SliDeRulE to determine the risk factors associated with the design elements. The results are shown in Table 1.6. The alternative design using cast iron piping was found to have a lower safety risk value. The difference in risk values is, to a great extent, related to the additional spool fabrication 6

8 7 Construction SliDeRulE Case Studies activity for PVC piping, and the greater risk during pipe placement and connection for PVC piping than for cast iron piping. Table 1.6: Comparison of As Built and Alternative Foundation Piping Systems Design Design Element Cumulative Risk Factor (Severity/Unit) Quantity Total Design Risk As built PVC piping (unit: linear feet) LF 0.73 PVC pipe hangers (unit: each) NA* Alternative Cast iron piping (unit: linear feet) LF 0.14 Cast iron pipe hangers (unit: each) NA* *Not available from design documents 7

9 8 Construction SliDeRulE Case Studies LHBCC Risk Summary Table 2.24 provides a summary of the risk values for the as built designs and alternative designs in the LHBCC that were selected for analysis. The table shows that more safety risk is present when constructing the exterior enclosure than when installing the piping at the foundation level. In addition, use of the selected alternative designs would have reduced the worker safety risk during construction of the building. Table 2.24: Summary of Risk Values for As built and Alternative Design Elements in the LHBCC Total System Design Design Element Quantity Design Risk Exterior Enclosure Plumbing As built Brick veneer curtain wall with steel and wood stud back up wall 3,485 SF Alternative Glass and aluminum curtain wall stick built system 3,485 SF 91.1 As built PVC piping 346 LF 0.73 Alternative Cast iron piping 346 LF 0.14 As built design total risk Alternative design total risk

10 9 Construction SliDeRulE Case Studies References Construction SliDeRulE for Buildings, Dharmapalan, V. (2011). Risk Factor Quantification of Design Elements for Multistory Commercial Office Buildings. MS Thesis, School of Civil and Construction Engineering, Oregon State University, Dharmapalan, V., Gambatese, J.A, Fradella, J., and Vahed, A.M. (2014). Quantification and Assessment of Safety Risk in the Design of Multistory Buildings. Journal of Construction Engineering and Management, ASCE, Nov. 2014: Dharmapalan, V. and Gambatese, J.A. (2012). Comparison of Design Risk Factors of Multistory Commercial Office Buildings. Proceedings of the ASCE Construction Research Congress 2012, West Lafayette, IN, May 21 23,