Citation
Determination Of Wind Out-Of-Plane Failure Capacity Of Plywood And Osb-Clad Walls Systems

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Title:
Determination Of Wind Out-Of-Plane Failure Capacity Of Plywood And Osb-Clad Walls Systems
Series Title:
19th Annual Undergraduate Research Symposium
Creator:
Lopez, Jason
Language:
English
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Undetermined

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Subjects / Keywords:
Center for Undergraduate Research
Center for Undergraduate Research
Genre:
Conference papers and proceedings
Poster

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Abstract:
Roof sheathing has been the subject of study for many wind engineers due to the high probability of being subjected to large uplift loads during intense wind occurrences. Meanwhile, wall sheathing has gone overlooked and usually assumed to have the same capacity of roof sheathing. The goal of this study is to determine the static out-of-plane wind capacity of wall sheathing on wood framed construction because currently there is no data available for wall sections that represent a typical wall section built in practice in the US. The current study uses a monotonic static wind with a step-and-hold to test panels to failure. The mean capacity attained after testing 10 samples of plywood and 10 samples of OSB sheathing was 4.21 kPa (88 psf). This capacity value along with its coefficient of variation, will provide a resistance model for inclusion in component-based damage prediction models. The performance of wall sheathing is compared to roof sheathing with the development of fragility curves that show the likelihood of failure of a structural sheathing panel for a given wind speed. It was shown that roof sheathing panels have a higher probability of failure when compared to wall sheathing panels. ( en )
General Note:
Research authors: Jason M. Lopez, David B. Roueche, David O. Prevatt - University of Florida
General Note:
University Scholars Program, McNair Scholars
General Note:
Faculty Mentor: Roof sheathing has been the subject of study for many wind engineers due to the high probability of being subjected to large uplift loads during intense wind occurrences. Meanwhile, wall sheathing has gone overlooked and usually assumed to have the same capacity of roof sheathing. The goal of this study is to determine the static out-of-plane wind capacity of wall sheathing on wood framed construction because currently there is no data available for wall sections that represent a typical wall section built in practice in the US. The current study uses a monotonic static wind with a step-and-hold to test panels to failure. The mean capacity attained after testing 10 samples of plywood and 10 samples of OSB sheathing was 4.21 kPa (88 psf). This capacity value along with its coefficient of variation, will provide a resistance model for inclusion in component-based damage prediction models. The performance of wall sheathing is compared to roof sheathing with the development of fragility curves that show the likelihood of failure of a structural sheathing panel for a given wind speed. It was shown that roof sheathing panels have a higher probability of failure when compared to wall sheathing panels. - Center for Undergraduate Research, University Scholars Program, McNair Scholars

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University of Florida
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Copyright Jason Lopez. Permission granted to University of Florida to digitize and display this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.

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Jason M. Lopez 1 David B. Roueche 2 David O. Prevatt 3 1. Undergraduate Assistant Civil Engineering, University of Florida, Gainesville, FL 2. Assistant Professor Dept. of Civil and Coastal Engineering, Auburn University, Auburn, AL 3. Associate Professor Dept. of Civil and Coastal Engineering, University of Florida, Gainesville, FL Introduction The purpose of this study is to determine the static out of plane wind capacity of wall sheathing on wood framed construction There have been several studies that have evaluated the wind uplift capacity of roof sheathing, i e structural sheathing supported transversely by wood framing at 610 mm on center However, there are very few studies that have been performed to evaluate the out of plane capacity of structural panels supported longitudinally by wood framing at 406 mm on center Such a resistance model is needed for inclusion in component based damage prediction models for light wood frame structures under extreme wind loads Objectives Determine the failure capacity of both Plywood and OSB clad wall sheathing specimens. Determine whether failure capacity is significantly affected by sheathing type (OSB vs Plywood). Determine load displacement difference between roof sheathing test vs. wall sheathing test. Develop fragility curves for the performance of wall sheathing under extreme wind loads. Figure 8: Fragility curves for each ASCE 7 10 wind load zone. Test Procedure For this experiment, the pressure is increased monotonically in a step and hold approach The pressure is stepped in increments of 0 48 kPa and held for 60 s and repeated until failure of test specimen Failure occurs once the panel separates from the wood framing and the blower can no longer maintain a constant air pressure The failure pressure is taken as the maximum absolute pressure maintained by the system prior to the panel giving way and the system losing pressure String potentiometers measure displacement of panel and an interior stud at the vertical midpoint of the panel 10 OSB and 10 Plywood samples were tested Panel Failures Test Equipment Pressure Loading Actuator (PLA) Pressure Transducer (PT) String Potentiometer (SP) Test Chamber Results Conclusions Acknowledgements Out of plane failure capacity of wall sheathing systems followed a normal distribution with a mean of 4 21 kPa and a standard deviation of 0 49 kPa No significant difference between out of plane capacity of Plywood and OSB wall systems was found The most common failure mechanism was nail withdrawal in either of the two center studs The percent difference between mean failure capacities of wall and roof sheathing was 16 5 % even though there is a 61 % increase in nails in wall sheathing This suggests that the tributary area of each fastener is more important to the capacity of the panel than the total number of nails Roof sheathing panels generally have a higher probability of failure for a given wind speed than wall sheathing panels Figure 7: (a) Wind Load Zones (ASCE 7 10). (b) Comparison of Normal Cumulative Distribution Function and Empirically derived CDF. Fragility Analysis References The mean failure capacity of the OSB structural panels is determine to be 4 1 kPa with a standard deviation of 0 43 The mean failure capacity of the Plywood structural panels is determine to be 4 3 kPa with a standard deviation of 0 53 The Wilcoxon Rank Sum Test is used to test the null hypothesis that there is no difference between the mean pressures of Plywood and OSB clad At a significance level of = 0 05 it was found that there is no that there was no statistical difference in failure pressures among the two groups P value = 0 52 The failure capacity of all wall sheathing panels is determined to follow a normal distribution with mean of 4 21 kPa and standard deviation of 0 49 kPa The mean stiffness coefficient for OSB and plywood panels is 9 21 kN /m and 8 79 kN /m respectively Datin P. L et al (2011). "Wind Uplift Capacity of Residential Wood Roof Sheathing Panels Retrofitted with Insulating Foam Adhesive." J. Archit. Eng. 17(4), 144 154. Hill, K. M. (2009). "Development of time varying wind uplift test protocols for residential wood roof sheathing panels." Masters Thesis UF, Gainesville, Fla. Lee, K. H., & Rosowsky D. V. (2005). Fragility assessment for roof sheathing failure in high wind regions. Engineering Structures 27 (6), 857 868. Roof sheathing generally has higher probability of failure than wall sheathing at a given wind speed Failure probability of wall corner panels can exceed that of roof sheathing in field zones of the roof Determination of Wind Out of Plane Failure Capacity of Plywood and OSB clad Walls Systems (a) (b) Figure 1: (a) Nail pattern of roof sheathing. 33 nails per panel (Hill 2009). (b) Loss of roof sheathing Hurricane Katrina (FEMA et al. 2006). Wall Sections The wall sections being tested are intended to represent a typical 2 4 m in height wood framed wall that can be found in practice The wall sections are built from Spruce Pine Fir (SPF) dimensional lumber The framing members are placed 406 mm on center and nailed to a single bottom plate and a double bottom plate A sheet of 4 mil plastic is laid over the studs This plastic sheet will provide a seal around the edges and will ensure that there is no pressure loss until failure The structural panel is nailed to the wood framed wall section using 6 d smooth shank common nails on a 152 / 305 nailing pattern Figure 2: Typical 1.2 m wide section for 2.4 m wall height with 152/305 nail pattern. 62 nails per panel. (b) (a) (c) Figure 3: (a) PLA device (Hill 2009). (b) SP device connected to stud and panel supported by wood frame. (c) Test Chamber with test sample. Table 1: Plywood and OSB Failure pressures and displacements at Failure. Figure 5: Typical recorded results. (1 st OSB test.) Red x indicates point at which failure occurred. Nail pulls through structural panel. Nail remains lodged in panel and is pulled out of framing member. No separation of panel and framing member and connection at bottom or top plate shears. Panel or framing member fractures. Partial withdraw of nail. (b) (a) (c) Figure 4: (a) Wall sheathing failure 2015 Garland, Texas tornado (image D. O. Prevatt). (b) Nail pull out. (7 th OSB test) (c) Connection shear. (6 th Plywood test) I would like to thank my mentors Dr David O Prevatt and Dr David B Roueche for having patience with me as I go through the process of learning how to do scholarly research Their knowledge in the field of wind engineering is invaluable and having the opportunity to work with them is a great honor The research was conducted under the National Science Foundation (NSF) Award 1150975 CAREER : Tornado Resilient Structural Retrofits for Sustainable Housing Communities (b) (a) Figure 6: Typical failure mode and location of nails. The fragility of the wall sheathing panels was evaluated using the wall sheathing capacity distribution and estimated wind load distributions within a Monte Carlo simulation framework The fragility of roof sheathing panels was also evaluated for comparison, using resistance statistics for panels fastened with 6 d nails at 152 : 305 mm spacing from Datin et al ( 2010 ) Wind loads were taken from ASCE 7 10 with uncertainties in the loading as described in Lee and Rosowsky ( 2005 )