Inelastic post-buckling behavior of tubular struts

A numerical procedure for tracing the inelastic post-buckling load-deflection path of tubular struts is proposed. The analysis accounts simultaneously for both the geometrical and material nonlinearities with special emphasis placed on the influence of strain-unloading. An iterative numerical arc-length technique is employed in the solution procedure, but once strain-unloading is detected, iterations are suppressed and the procedure converted to a pure incremental method with arc-length constraint only. Predictions of the maximum loads and of the post-buckling load-deflection paths using the proposed approach compared very well with other published analytical results and with tests. The approach is simple and may be applied to general thin-walled cross sections and to include cyclic loading.