CSM design of cold-formed lean duplex stainless steel tubular sections under concentrated transverse loading

A new approach to the design of stainless steel tubular sections against web crippling, based on the continuous strength method (CSM), is presented. The studied profiles are cold-formed lean duplex stainless steel square and rectangular hollow sections. The sections are subjected to End-One-Flange (EOF), End-Two-Flange (ETF), Interior-One-Flange (IOF) and Interior-Two-Flange (ITF) loading conditions. Finite element models are first validated against experimental results under the four loading conditions and then employed to perform an extensive numerical parametric study. The key parameters in the numerical analysis include the ratios of the flat web height-to-thickness, the load bearing length-to-web thickness, the section inner radius-to-web thickness and the load bearing length-to-flat web height. A total of 285 new numerical results are generated. The numerical results are used, together with 47 existing test results, to develop a new CSM-based design approach for web crippling and to assess the accuracy of the new proposals relative to the predicted web crippling strengths given by current codified design equations. Reliability analyses of the considered design methods are also conducted. Overall, it is shown that the proposed CSM is able to provide more accurate and reliable resistance predictions compared with the existing codified design equations.