A stiffened-plate buckling model for calculating critical stress of distortional buckling of CFS columns

This paper presents a stiffened-plate buckling model for calculating the critical stress of distortional buckling of cold-form steel (CFS) channel-section columns. The model is the further extending of the buckling model we developed recently for beams (International Journal of Mechanical Sciences 2016, 115/116: 457-464) to columns. In the present buckling model, the web is treated as a plate which has both in-plane and out of plane bending deformations, whereas the flange and lip are modelled as the angle stiffener applied at the two ends of the web, which is subjected to asymmetric bending and torsion. The critical buckling stress of the stiffened plate is calculated using the classical principle of minimum potential energy. To validate the present stiffened plate buckling model, finite strip analysis is also carried out to the CFS channel-section columns. Good agreement is demonstrated between the critical stress calculated from the present stiffened plate buckling model and that obtained from the finite strip analysis.