Ultimate Behavior and Design of Cold-Formed Steel Square Hollow Section Members

The ultimate behavior and design of cold-formed steel square hollow section (SHS) members are investigated in the present study, with the focus on their local buckling behavior under pure compression and pure bending, as well as combinations of compression and bending. Finite element (FE) models are established and validated against existing experimental data collected from the literatures; the FE models take into account the initial local imperfections, geometric and material nonlinearities, and cold-formed effect. Following the validation, the FE models are utilized to perform a series of parametric studies, considering different cross-section width-to-thickness ratios and loading cases. The stress distributions within the critical cross-section of the SHS members under different loading conditions are investigated and an effective plastic width method (EPM) is proposed for the determination of the ultimate resistance of SHS in compression and bending. The numerically obtained results are used to assess the accuracy of the existing design rules stipulated in the Chinese and European design codes and the proposed EPM. It is shown that the proposed EPM is able to provide more accurate design predictions in relative to the codified design approaches, owing largely to its rational considerations of the strain hardening, cold-formed effect and partial plasticity of the cold-formed SHS members.