Experimental study of unlipped channel beams subject to web crippling under one flange load cases

Abstract

Cold-formed steel members are becoming increasingly popular in the building industry due to their superior strength to weight ratio and ease of fabrication as opposed to hot-rolled steel members. However, they are susceptible to various buckling modes at stresses below the yield stress of the member because of their relatively high width-to-thickness ratio. Web crippling is one of the failure modes that occurs in steel channel sections under transverse concentrated loads or reactions. Recently a test method has been proposed by AISI to obtain the web crippling capacities under both one-flange and two-flange load cases. Using this test method 21 tests were conducted in this research to investigate the web crippling behaviour and strengths of an unlipped channel section with stocky webs known as DuraGal Channels under end-one-flange (EOF) and interior one-flange (IOF) load cases. DuraGal channels with different web slenderness and bearing lengths were tested with their flanges unfastened to supports. In this research the suitability of the currently available design rules for unlipped channels subject to web crippling under one flange load cases was investigated, and suitable modifications were proposed where necessary. This paper presents the details of this experimental study and the results.