Local–distortional interaction in cold-formed steel rack-section columns

Experimental and numerical results concerning the post-buckling behaviour and strength of fixed-ended cold-formed steel rack-section columns experiencing local–distortional (L–D) interaction are reported. The experimental results, obtained from tests carried out at The University of Hong Kong include initial imperfection measurements, equilibrium paths and failure loads/modes – they provide clear evidence of the above coupling phenomenon. After presenting and discussing a comparison between test results and the values yielded by the corresponding Abaqus shell finite element numerical simulations, the experimental failure loads are used to assess the quality of their estimates provided by design approaches based on the Direct Strength Method (DSM) that were recently developed exclusively for fixed-ended lipped channel columns affected by L–D interaction. The work also includes a comparison between the ultimate strength and DSM design of lipped channel and rack-section columns undergoing similar L–D interaction effects.