Design of cold-formed steel lipped channel columns under local–distortional buckling interaction

Cold-formed steel lipped channel columns are widely used. The bearing capacity of columns is often affected by local buckling, distortional buckling and local–distortional buckling. The direct strength method (DSM) is suitable for the calculation of distortional buckling. However, previous studies have shown that the calculated value according to the DSM formula without considering the influence of local–distortional buckling tends to be unsafe. There is currently no universal formula for the calculation of local–distortional buckling. Based on the experimental data in the literature, in this paper the authors propose to introduce the critical force of elastic local–distortional buckling into the current DSM formula to consider the influence of local–distortional buckling. Compared with the current DSM calculation formula, the calculated results using the proposed method are in good agreement with the experimental data for cold-formed steel lipped channel columns affected by local–distortional buckling. The proposed method is computationally compatible with current DSM; that is, under certain conditions, the method is equivalent to DSM. In addition, the proposed method is universal and can provide a reference for the buckling calculation of different modes of other types of members.