Torsional Buckling of Thin-Walled Columns with Transverse Stiffeners: Analytical Studies

In this paper the pure torsional buckling of thin-walled column members is investigated, with a special focus on the effect of transverse plate elements, such as end-plates or transverse stiffeners. The linear buckling problem is aimed to solve analytically, therefore the necessary (differential) equations are first established. For some simple problems, namely doubly-symmetric I-sections with pinned-pinned or clamped-clamped supports and with rectangular stiffeners or end-plates, closed formulae are derived to calculate the critical force. It is shown that the transverse elements have two effects: the direct effect is due to the deformation of the transverse elements, while the indirect effect is that the transverse elements modify the longitudinal distribution of the member’s displacements. It is also shown how the stiffener-to-member connection influences the results. The analytical solutions are discussed by several numerical examples: the results from the derived formulae are compared to results from shell finite element buckling analyses.