Non-linear lateral buckling analysis of unequal thickness thin-walled box beam under an eccentric load

Abstract

A non-linear theory for straight thin-walled box beam (STBB) subjected to an eccentric force, considering the distortional deformation and unequal thickness of the webs, is developed to determine the buckling capacity in this paper. Due to the coupling of warping, torsion and distortion of the cross-section, the kinematic model becomes considerably complicated. The theory considers the geometric non-linear coupling caused by the non-linear terms in each deformation mode under the generalized displacement coordinate. The non-linear differential equations is discretized by Galerkin's method, which has been shown that the interaction effects can be successfully captured between the pre-buckling deflections and geometric non-linearity. The post-buckling response of the present beam model is compared with the results of the finite element simulation (Ansys15.0) and F.Mohri's method (2002), which appears to be very conservative. The formulation is solved exactly by checking the effect of the variable parameters: the width-to-height ratio of the cross-section, the load height and the thickness of the webs. The viability and effectiveness of this method has been established by comparing with other existing numerical solutions.