Abstract
The combined behaviors of the local and overall buckling deformations of the U-section members subjected to the axial loads are analyzed by the finite element method. In the finite element method, isoparametric degenerated shell element is adopted, and only the geometrical nonlinearity is considered based on the Green Lagrange strain definition. To solve the nonlinear equation, the displacement incremental scheme employed, in which the incremental axial displacements are added to the ends of the members. As the initial imperfections, four types of initial imperfections are introduced, 1) the bulge type of imperfection, 2) the local type of imperfection, 3) the global type of imperfection, and 4) the combined imperfection of local and global ones. For the local type of imperfection, the buckling mode corresponding to the local buckling load obtained by the transfer matrix method is introduced.
