Straight-Beam Approach for Analyzing Lateral Buckling of Thin-Walled Curved I-Beams

The straight-beam approach is a simple and efficient means for analyzing the buckling of curved beams. Although previous researchers showed that the straight-beam approach is capable of simulating the lateral buckling of solid curved beams, the warping effect had been neglected and thus its practical application in engineering was limited. In this study, thin-walled curved I-beams will be dealt with by assuming the warping degrees of freedom (DOFs) to be identical at the common node for non-aligned connected elements. One feature of the present formulation is that the moments induced by initial nodal moments undergoing out-of-plane rotations are duly considered in the geometric stiffness matrix, while the compatibility and equilibrium are enforced for angled joints at the deformed position. With high computational efficiency, the present approach obtains buckling loads that agree well with the theoretical curved-beam solutions or the ones obtained by ABAQUS using shell elements. Compared with the modern curved-beam elements, the straight-beam element is locking free, invariant and simple in formulation, since the effect of curvature is not involved in global assembly.