Laboratory Tests and Simulations on Loading Performance of Cold-Formed Steel Purlin-to-Sheet Roofing Structures

Abstract

Cold-formed steel (CFS) purlins, which possess a high load-carrying capacity compares to their weight, are extensively utilized in roof systems. Within purlin-to-sheet systems, roofing sheets provide additional lateral restraint to purlins, thereby enhancing the load-bearing capacity of the system. This research conducts both laboratory tests and simulations to evaluate the behavior of purlin-sheet systems under downward loading, focusing on ultimate bending moment and failure modes. To enhance predictive precision, a meticulous exploration of influential parameters is undertaken through comprehensive parametric analysis, identifying purlin thickness, steel material strength, roofing sheet thickness, and the number of lateral struts as critical factors influencing load-bearing capacity. It indicates that thickness, yield strength and lateral sturts of the purlins significantly impact structural load-bearing performance, whereas the contribution of roof panel thickness to load capacity is comparatively minor. For the purlin with small shell thickness (i.e., less than 1.5 mm), the main failure modes are distortional buckling at the upper flange and local buckling at the web. As the thickness of the purlin increases, the main buckling mode gradually shifts towards distortional buckling.