This paper describes the distortional buckling behaviour of a series of innovative cold-formed steel columns. More than 15 laboratory experiments were undertaken first on these innovative steel columns of intermediate length under axial compression. All of these columns failed by distortional buckling with very little post-buckling strength. The section and buckling properties of the columns were determined using the finite strip analysis program THINWALL. The distortional buckling and nonlinear ultimate strength behaviour of the columns was investigated in detail using finite element analyses (ABAQUS). The finite element analyses included relevant geometric imperfections and residual stresses. The deflection and strain results from the experiments compared well with those from the analyses. The ultimate design load capacities were evaluated using the provisions of Australian Cold-formed Steel Structures Standard AS/NZS 4600-1996, and were compared with those from experiments and finite element analyses. A series of parametric studies was also carried out by varying the yield strength, thickness and column length. Details of this investigation and the results are presented in this paper.
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