Improved shell-finite strip method for inelastic buckling analysis of thin-walled steel members with residual stresses

Abstract

This study investigates the inelastic buckling behavior of thin-walled steel members, with a specific focus on cold-formed steel members considering residual stresses. This behavior is essential for determining load-bearing capacities, yet it is often influenced by complex factors such as local-global interactive buckling, material yielding, and residual stresses. Current methods, including the Direct Strength Method (DSM), predominantly rely on the elastic Shell-Finite Strip Method (SFSM) and empirical formulations, which are primarily suited for regular cross-sections but less effective for those with complex geometries. Alternatively, the advanced Shell Finite Element Method (SFEM) is highly adaptable to various cross-sections and delivers accurate analyses; however, its significant computational cost limits routine applications. This research introduces an improved SFSM that integrates material inelasticity and residual stresses, enabling efficient and accurate buckling analysis for thin-walled steel members with arbitrary cross-sections. Validation using five examples demonstrates the accuracy and computational efficiency of proposed method, showing strong agreement with experimental data and SFEM results. The developed algorithms are implemented in the free educational software platform MSASect2.