Investigating the effect of bearing stiffeners on the web crippling capacity of lipped channel beams

Abstract

Cold-Formed Steel (CFS) sections are widely utilised in the construction industry due to their significant structural and economic advantages. However, due to their thin-walled geometry, they are susceptible to local failures, such as web crippling. This failure mode is further intensified by the service holes used for utilities. This study investigates the web crippling behaviour of cold-formed steel lipped channel beams under Interior Two Flange (ITF) loading, focusing on the influence of web perforations and transverse stiffeners. Current design standards do not adequately address the combined effects of web openings and stiffeners under TIF loading. Sixteen lipped channel specimens with varying stiffener configurations and web openings were fabricated and tested under TIF loading according to the American Iron and Steel Institute (AISI 5909) standard. The experimental program measured load-deflection responses, ultimate web crippling capacities, and failure modes for each configuration. Results showed that using transverse stiffeners can increase the web crippling capacity by 58.1-117.6% compared to beams without stiffeners. When beams contain web holes, the web crippling strength is significantly reduced, especially when aligned beneath the bearing plate. However, transverse stiffeners can restore the capacity by 60.2-119.4%, depending on the location of the web hole. These findings provide valuable experimental data and insights for the development of improved design guidelines.