Mode interaction in thin-walled trapezoidal column under uniform compression

Abstract Interaction of nearly simultaneous buckling modes in the presence of imperfections is studied. The investigations is concerned with thin-walled trapezoidal columns under uniform compression. In these structures two modes are of particular interest, namely a local short-wave and an overall long-wave buckling mode of the whole structure, respectively. The asymptotic expansion established by Byskov and Hutchinson is also used here. The present paper is devoted to the study of equilibrium paths in the advanced post-buckled region of imperfect columns. The bifurcation stress is determined analytically and the asymptotically exact expansion is obtained for the initial post-bifurcation behaviour. The calculations are carried out for several types of rectangular and trapezoidal columns.