Effects of initial imperfections on nonlinear behaviors of thin-walled members

The effects of the initial imperfections on the nonlinear behaviors and ultimate strength of<br />the thin-walled members subjected to the axial loads, obtained by the finite element stability analysis, are<br />examined. As the initial imperfections, the buckling mode shapes of the members are adopted. The<br />buckling mode shapes of the thin-walled members are obtained by the transfer matrix method. In the<br />finite element stability analysis, isoparametric degenerated shell element is used, and the geometrical and<br />material nonlinearity are considered based on the Green Lagrange strain definition and the Prandtl-Reuss<br />stress-strain relation following the von Mises yield criterion. The U-, box- and I-section members<br />subjected to the axial loads are adopted for numerical examples, and the effects of the initial<br />imperfections on the nonlinear behaviors and ultimate strength of the members are examined.