Flexural-Torsional Buckling of Isotropic and Transversely Isotropic Thin-Walled Members
The exact theory of thin-walled isotropic beams developed by Capurso in 1964 eliminates the limitations of Vlasov theory in computing the flow of tangential stresses generated by torsion. It also removes the limitations related to St. Venant’s principle and thus allows computing the state of stress generated by arbitrary load distributions. In a previous work, the Authors generalized Capurso’s theory to transversely isotropic materials, with particular reference to fiber-reinforced polymer (FRP) pultruded profiles, and showed that for the latter the discrepancy between predictions of Vlasov and exact theories can be significantly larger than for steel profiles. In this paper, the exact theory of thin-walled beams is used as a basis for the global buckling analysis of isotropic and transversely isotropic structural members under axial compression. The effect on the critical load of the actual distribution of the applied compressive stresses is analized. A numerical example is presented for the I-section.