Finite member element model for lateral buckling of thin-walled members

The following two assumptions, made by Vlasov, are used to compute their deformations on the theory of thin-walled members stability: (a) rigid cross section; (b) No shearing strains in the middle surface of walls. The second assumption, based on pure torsion, is not suitable to non-uniform torsion. The shear lag phenomenon, induced by the shearing strains in the middle surface of walls, can be shown in some structures gravely. The present study is focused on establishing a finite member element model, based on energy principle, to estimate the lateral buckling capacity of thin-walled members. In the method the effects of torsion, warping and the shearing strains in middle surface of the walls are taken into account. Compared with the results from classical theory, energy method and finite element method, the numerical results demonstrate the efficiency of the proposed method. Because no need to introduce the concepts of shear centre and sectorial co-ordinate, the method is easily understood and applied. It is emphasized that the energy equation for buckling analysis is applicable for thin-walled members with any cross section.