Inelastic buckling analysis of cold-formed steel members with residual stresses based on CFSM

Abstract

Residual stresses in cold-formed steel members are generally composed of a membrane component and a bending component, which may result in the inelastic buckling of cold-formed members. The complex finite strip method (CFSM) has been widely used to analyze the buckling of thin-walled members and it can handle shear effects easily. As for inelastic buckling, the available CFSM mainly focuses on the local buckling of plates and cannot be applied to the buckling of cold-formed members that can buckle in a distortional or global mode. Besides, the bending component may be hard to be incorporated into the finite strip method. In the present study, a modified CFSM is proposed to analyze the inelastic buckling of cold-formed steel members with residual stresses. The effects of the membrane and bending components on inelastic buckling are considered through the applied stresses and modifying material properties, respectively. The results calculated by the proposed model are compared to the available solutions of several examples in previous studies, and good agreements are observed. Based on the proposed model, the effects of residual stresses on the inelastic buckling of plates and cold-formed members are investigated. The results show that the inelastic buckling stress is significantly lower than the elastic buckling stress when the elastic buckling stress exceeds the yield stress. The membrane component has a significant influence on the inelastic buckling stress of plates. The bending component mainly affects the inelastic local buckling of members under compression and the inelastic global buckling of members under compression as well as bending and shear.