Web crippling of lean duplex stainless steel tubular sections under concentrated end bearing loads

A series of tests was conducted to investigate the web crippling behaviour of cold-formed lean duplex stainless steel (LDSS) tubular sections. The LDSS had two grades, including EN 1.4062 and EN 1.4162. The tests were performed under three different conditions of concentrated end bearing loads, namely, the loading conditions of End-One-Flange (EOF), the End-Two-Flange (ETF) and end loading (EL). The loading conditions of EOF and ETF are specified in the American and Australian/New Zealand cold-formed stainless steel design specifications, while the loading condition of EL simulated the floor joist members positioned on a solid foundation under concentrated end bearing load. The test specimens were mainly failed by web crippling. The test strengths were compared with the predicted strengths that calculated by the stainless steel design specifications, including the American Society of Civil Engineers (ASCE) Specification, Australian/New Zealand Standard (AS/NZS) and European Code (EC). In addition, the web crippling strengths predicted by the North American Specification (NAS) for cold-formed carbon steel structures and using the design equations proposed in the literature for cold-formed duplex stainless steel tubular sections were also compared with the test strengths. It was found that the predicted strengths calculated by the ASCE, AS/NZS and EC specifications are conservative and reliable for LDSS sections under the three different concentrated end bearing loads. The predictions by NAS and proposed equations in the literature are generally less conservative compared with those by ASCE, AS/NZS and EC. However, the predictions by NAS are found to be unconservative and not reliable for the loading condition of ETF.