Unified formulae for critical load and unified DSM expressions for pinned-end and fixed-end columns exhibiting pure distortional buckling

Unified formulae of elastic critical distortional buckling load and unified DSM expressions for columns undergoing pure distortional buckling, are proposed in this study for both pinned-end and fixed-end columns with a C/Z/hat sections. The normal stress distribution of pre-buckling and post-buckling for C-section columns undergoing distortional buckling is presented based on theoretical analysis and literature review. The basic purpose of the DSM expressions is to express the strength problem as a stability problem to determine the ultimate strength of columns experiencing pure distortional buckling. To understand the effects of both pinned-end and fixed-end conditions in the columns undergoing pure distortional buckling, the effective length factor of flexural buckling about the strong axis of a cross-section, is introduced into elastic distortional buckling load formulae and the DSM expressions. Numerical results computed by computer software (CUFSM), along with numerical and experimental results in literature reviews are used to assess the accuracy of the proposed formulae. It is shown that the proposed formulae are accurate and universal.