Pre-Fabricated Gable Frame Design in High Snow Regions- Comparison of LRFD and ASD
Naser Katanbafnezhad, Alan Hoback
American Journal of Engineering Research (AJER), vol. 9(6), 2020, pp. 160-168.
Abstract:
The LRFD and ASD methods do not produce the same designs. The biggest discrepancies are in cold regions with a high snow load because of different ways of handling the safety factors for snow. The results were shown for structures in Berlin, NH and Government Camp, OR, USA which are located in high snow regions. Precise practical designs of gable frames with a high snow load show that LRFD and ASD can produce results that vary by up to 41% with LRFD usually producing the lighter weight design for roof angles above a pitch of 7 to 12. Results were a function of other loads, roof angles, and span to height ratios. The implication is that designers in cold regions need to either be familiar with how the methods vary, or design with both methods in order to find the least weight design.
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References
[1]. American Society of Civil Engineers: ASCE 7-16- Minimum design loads and associated criteria for buildings and other structures, (2016).
[2]. Geis, J., Strobel, K., & Liel, A.: Snow-induced building failures. J. of Performance of Constructed Facilities, 10.1061/(ASCE)CF.1943-5509.0000222, 377-388, (2011).
[3]. Holicky, M., & Sykora, M.: Failures of roofs under snow load: Causes and reliability analysis. Forensic Engineering 2009: Pathology of the Built Environment, 444-453, (2010).
[4]. Bean, B., Maguire, M., & Sun, Y.: Comparing Design Ground Snow Load Prediction in Utah and Idaho. J. of Cold Regions Eng., 10.1061/(ASCE)CR.1943-5495.0000190, 04019010, (2019).
[5]. McCauley, A. J., Knuuti, K., & Mlakar, P.F.:Ground Snow Loads Revisited. Proc., 16th Int'l. Conf. on Cold Regions Eng., Salt Lake City. 322-333, (2015).
[6]. O'Rourke, M., & Auren, M.: Snow loads on gable roofs. J. of Structural Eng., 10.1061/(ASCE)0733-9445(1997)123:12(1645), 1645-1651, (1997).
[7]. Katanbafnezhad, N., & Hoback, A.S.: Comparison of LRFD and ASD for Pre-Fabricated Gable Frame Design. American Journal of Engineering Research (AJER), vol. 9(05), pp. 120-134, (2020).
[8]. American Institute of Steel Construction: Specification for Structural Steel Buildings, ANSI/AISC 360-16, Chicago, IL, (2017).