Optimum roof angles of steel gable frames with pinned supports

Naser Katanbafnezhad, Alan Hoback

International Journal of Modern Research in Engineering & Management (IJMREM), vol. 2(4), 2020, pp. 8-17.

Abstract:

Optimum roof slopes were found for steel gable frames with pinned supports. Five locations, Detroit MI, Miami FL, Santa Barbara CA, St. Paul MN and Berlin NH, were chosen because they represented a variety of loading conditions. Multiple structures were designed for each location with span to height ratios from 1 to 10, and roof angles from 10 to 45 degrees. Analysis was done for each case using ETABS. This provided patterns in stress efficiencies that the helped identify possible optimum angles. Precise designs with the LRFD method were performed on each roof angle for each span length if it was a candidate for the optimum. It was found that for low snow load areas, a low roof angle is optimum. However, as roof load and span increase, the optimum roof angle is higher. A primary factor in determining roof angles in these situations was having an angle high enough so that unbalanced snow loading was not required by the code.

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References

[1]. Katanbafnezhad, Naser, & Hoback, Alan, S. (2020). Comparison of LRFD and ASD for Pre-Fabricated Gable Frame Design, American Journal of Engineering Research (AJER), vol. 9(5), pp. 120-134.
[2]. Katanbafnezhad, Naser, & Hoback, Alan, S. (2020). Pre-Fabricated Gable Frame Design in High Snow Regions- Comparison of LRFD and ASD, American Journal of Engineering Research (AJER), vol. 9(6), pp. 160-168.
[3]. Truman, Kevin Z., & Hoback, Alan S. (1993). Optimization of steel piles under rigid slab foundations using optimality criteria, Structural Optimization, Vol. 5, No. 1.
[4]. Hoback, Alan, S., & Truman, Kevin Z. (1994). A New Method of Finding the Global and Discrete Optimums for Structural Systems, Computers and Structures, Vol. 52, No. 1.
[5]. Peng, Liu. (2001). Optimization Design of Portal Frames [J]. Industrial Construction 7.
[6]. Saka, M. (2003). Optimum design of pitched roof steel frames with haunched rafters by Genetic algorithm. Computers & Structures. 81. 1967-1978. 10.1016/S0045-7949(03)00216-5.
[7]. ASCE (2016). Minimum design loads and associated criteria for buildings and other structures, ASCE 7-16. American Society of Civil Engineers.
[8]. AISC (2017), Specification for Structural Steel Buildings, ANSI/AISC 360-16, American Institute of Steel Construction, Chicago, IL