Abstract
In this paper, a geometric and material nonlinear analytical method by the finite element method is presented in order to understand the maximum strength and elasto-plastic postbuckling behavior of plate elements of structural members. And then a simplified numerical method for coupled plate elements is established. The latter method is considered that plate finite element is used for the first buckling plate element and the restraining plate element is replaced with equivalent spring stiffness. In-plane stress distribution is constant because a constant strain and curvature triangular finite element is used in the present method. Therefore the progress of a plastic range has to be investigated only along the depth of the finite element divided into a number of layers. The validity of the present method is examined by the experiment on H-section stub-columns under uni-axial compression. In comparing the method using equivalent spring stiffness with the method using only plate finite element, elastic load-deflection curves are in good agreement, although the difference between them becomes large in the more advanced postbuckling range. As the maximum strength and plastic behavior after it can be understood by pursuing postbuckling behavior in the range of small deflection, it is shown that the method using equivalent spring stiffness is efficient in elasto-plastic problems.
