The Effect of Transverse Stiffeners on the Torsional Buckling of Thin-Walled Columns

In this paper the effect of transverse stiffeners on the torsional buckling of thin-walled members is discussed. Though the torsional behavior of thin-walled members is a classic topic of structural engineering university courses, there is no comprehensive understanding on how the transverse stiffeners modify the behavior. In the paper analytical solution is presented for pure torsional buckling. Analytical solution is possible by using the energy method, at least for simpler cases. Sometimes even closed-formed solutions are possible to achieve for the critical force, as illustrated by the solution of clamped-clamped columns with doubly symmetric I-shaped cross-section, with considering one or multiple transverse stiffeners. The analytical solutions are compared to shell finite element solutions, using a general purpose finite element software as well as the specific constrained finite element method, which has just recently been extended to handle members with transverse plate elements. The results illustrate the applicability and also the limitations of the various methods. Though the analytical solutions are possible to extend to more general cases, it does not seem to be realistic to provide a very general analytical formula due to the complexity of the problem. Still, the analytical solutions are helpful in understanding the effect of transverse stiffeners on the torsional behavior. Moreover, the results suggest that the transverse stiffeners have beneficial, and sometimes considerable effect on the critical load to pure torsional buckling of columns, which effect could be considered also in the design.

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