| Description |
viii, 60 leaves : illustrations ; 28 cm |
| Summary |
"Designing purlins for roof systems attached to through-fastened panels has been a subject well researched in the past. The current design specification uses a simplified approach to the designing of these members where the fully braced moment capacity of such members is multiplied by a reduction factor, commonly referred to as the R-value. This value represents the point in between the fully braced and fully unbraced member behavior. However, the current AISI Specification, S100, only contains R-values for purlins and girts up to 11.5 inches in depth. Since manufacturers are now rolling sections up to 12 inches deep, two confirmatory tests were performed with the goal of expanding the limits of the current design provisions. The intent of this research was to demonstrate that the R-value for the 11.5 inch deep Zee members is representative for members with depths of 12 inches as well. One continuous span and one simple span test were performed. Based on the findings of this test program, 12" deep Z-purlins do meet or exceed the required strength computed using the current AISI S100 R-values. Thus, it is recommended that the limitations of Section D6.1.1 be expanded to include these deeper 12" Z-purlins. With the increase in depth, the depth-to-flange width ratio should also be expanded. It is recommended that the upper limit of the depth-to flange width ratio be expanded to include members with depth/flange width ratios up to a value of 5.5. It is also recommended that Section D6.1.1 be changed to ensure ductile steel rather than limiting the yield stress of the material. It is suggested that the limiting Fu/Fy ratio of the member be 1.20"--Abstract, leaf iii. |
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