Fastened Aluminum-Lipped Channel Sections Subjected to Web Crippling under Two-Flange Loading Conditions: Experimental Study

Abstract

Thin-walled members in structural systems are highly vulnerable to buckling instabilities, including web crippling. Aluminum alloy members are more prone to this kind of failure due to their relatively low elastic moduli. As shown in the existing literature, limited research has been performed to investigate the web crippling failure of aluminum members. This paper presents the details of an experimental investigation conducted to study the web crippling phenomenon of fastened (restrained flanges) aluminum-lipped channel (ALC) sections. Two loading conditions, end-two-flange and interior-two-flange loading, were considered. Two series of 40 tests were performed using roll-formed aluminum alloy 5052 H36 specimens with different web slenderness and load-bearing lengths. A comparison between the ultimate capacities of the web crippling tests and the predictions from the currently available design rules was performed. The results show that the current web crippling design rules are mostly unsafe and unreliable for fastened ALC sections. Thus, a modified equation is needed to closely and accurately estimate the web crippling strengths for fastened ALC sections under two-flange loading conditions. Furthermore, the effect of restrained flanges on the web crippling mechanism is discussed in detail. It was observed that fastening the flanges considerably strengthened the section web crippling capacity. Hence, a new prediction approach was developed to estimate the increase of the web crippling capacity due to flange restraining.