Analytical method for distortional buckling load of cold-formed steel members with perforated web under bending moment

In order to reduce weight or meet specific functional requirements, cold-formed steel (CFS) members with perforated webs are widely used in practical engineering. However, these web holes, especially the un-stiffened ones, can result in stress concentrations and section deficiencies, leading to a reduction of the distortional buckling load. Existing specifications, such as the American Iron and Steel Institute (AISI 2016) and Australia New Zealand Standards (AS/NZS 4600:2018), do not fully consider this impact. By simplifying the perforated web into an equivalent beam model and modifying the calculation method of the web rotational stiffness, this paper proposes an analytical method for the distortional buckling load of perforated CFS members with arbitrary hole parameters, including the hole spacing, location, and geometric shape. The proposed method is verified by finite element analysis (FEA) and experiment results in the literature. The FEA result indicates that holes near the compressed flange or with smaller spacing can lead to more reduction in the distortional buckling load. Compared to existing methods, the calculation accuracy of the proposed method has been improved by 2% to 4%.