Imperfection sensitivity of plate girder webs under patch loading

摘要

This paper is aimed at studying the influence of initial shape imperfections on the postbuckling behavior of plate girder webs subjected to patch loading. In the last three decades, a large amount of experimental and numerical investigations has been dedicated towards the implementation of formulae for the resistance of plate girder webs subjected to different type of loading. On the one hand, it has been known that initial geometric and material imperfections produced in the manufacturing process can reduce the load capacity of the thin-walled webs used in most cases. On the other hand, it is difficult to include them in the formulae. Implementation of numerical approaches such as the finite element method allows researchers to perform computer simulations instead of performing cost expensive experiments. Data concerning the magnitude and shape of initial geometric imperfections for plate girders under patch loading is found in the literature. A sensitivity analysis is presented herein in order to investigate the effect of varying imperfection shape and amplitude on the postbuckling response and ultimate strength of plate girders under patch loading. This sensitivity analysis is performed by means of nonlinear finite element analysis. At first, the shape of the imperfections is based on the buckling modes resulting from an eigenvalue buckling analysis. Secondly, the amplitude of the buckling modes is varied, and then introduced in the nonlinear analysis. The results show the influence of these modes and amplitudes on the resistance to patch loading.