Element interaction of cold-formed stainless steel cross-sections subjected to major axis bending

• An investigation is performed on constituent plate element interaction effects of cold-formed stainless steel square and rectangular hollow sections in bending.
• The design provisions on Class 3 and Class 2 slenderness limits and effective width formulae are assessed.
• New Class 3 and Class 2 slenderness limits and the section moment capacity design equations are proposed based on the whole cross-section response, which carefully take into account of the interaction effects of constituent plate elements.

Numerical investigation of cold-formed normal and high strength stainless steel square and rectangular hollow sections subjected to major axis bending is presented in this paper. A non-linear finite element model which includes geometric and material non-linearities was developed and verified against experimental results. The material properties of the flat and corner portions of the specimen sections were carefully incorporated. It was shown that the finite element model closely predicted the failure modes, ultimate moments and deflections of the tested specimens. The model was then used for an extensive parametric study to investigate the interaction effects of constituent plate elements on Class 3 and 2 slenderness limits and cross-section moment capacities of cold-formed stainless steel square and rectangular hollow sections in bending.The numerical strengths predicted from this study together with the experimental results were compared with the theoretical elastic and plastic bending moments. It was shown that the element interaction surely influences the flexural behavior of cold-formed stainless steel square and rectangular hollow sections especially for slender cross-sections. The design provisions on Class 3 and 2 slenderness limits and effective width equations specified in ASCE Specification, EC3 Code and proposed by Gardner and Theofanous are not suitable for square and rectangular hollow sections in bending since they did not take into consideration interaction effects of constituent plate elements. Hence, the new Class 3 and Class 2 slenderness limits and the cross-section moment capacity design equations are proposed in this study based on the whole cross-section response, which carefully consider the interaction effects of constituent plate elements.