Bifurcation of locally buckled members

The paper presents a general bifurcation analysis of members that are locally buckled in the fundamental state. The members are assumed to be geometrically perfect in the overall sense such that bifurcation of the locally buckled member in an overall mode may occur. The analysis applies to arbitrary types of loads and support conditions. The cross-section, which may be arbitrary in shape, is assumed to be composed of flat plates. The paper derives the general variational equations expressing equilibrium of the fundamental and bifurcated states. The variational equations are applied to doubly symmetric columns and doubly symmetric beam-columns. The differential equations and boundary conditions are derived from the variational equations and solved for the fundamental and bifurcated states, thus providing the bifurcation loads of the members. (C) 1997 Elsevier Science Ltd.