Geometric non-linear analysis of box sections under end shortening, using three different versions of the finite-strip method

Three finite-strip methods, (FSM) namely the semi-energy, full-energy semi-analytical and the full-energy spline FSM, are developed for predicting the geometrically non-linear response of box sections with simply supported ends when subjected to uniform end shortening in their plane. The developed FSMs are then applied to analyze the post-local-buckling behavior of some representative box sections. Although, in general, a very good agreement is observed to exist among the results obtained by all the different methods, it is revealed that in the advanced stages of post-buckling, the semi-energy method predicts results which are slightly less accurate than those obtained by the full-energy methods. This is due to the fact that a slightly higher level of compressional stiffness is experienced in the case of the results obtained by the semi-energy approach as compared to those observed in the cases of the results obtained by the full-energy methods. It is however worth noting that the current semi-energy analysis is based on a single term approach. Thus, it is expected that the accuracy of the semi-energy approach will improve and correspondingly the number of degrees of freedom involved will increase if more than one term is utilized in its formulation.