Bifurcation analysis of thin-walled plain channel compression members

This paper presents a bifurcation analysis of thin-walled members subjected to uniform compression. The analysis uses an elastic non-linear finite strip buckling method to determine the flexural and torsional tangent rigidities of a section undergoing local buckling. The overall flexural and flexural-torsional bifurcation loads are calculated using these tangent rigidities. The bifurcation analysis is applied to thin-walled plain channel columns having different cross-sectional dimensions. The boundary conditions of the columns are fixed at each end, where both minor and major axis rotations, as well as twist rotations and warping, are restrained. Bifurcation curves of the plain channel columns are presented in the paper. The failure modes of the columns include local buckling, overall flexural buckling and overall flexural-torsional buckling. It is found that for some of the channel sections undergoing local buckling, the columns failed in flexural buckling, even though the critical buckling mode is flexural-torsional according to the classical theory of thin-walled members for undistorted cross-sections. The elastic local buckling loads are also determined using a rational buckling analysis. © 2004 Elsevier B.V. All rights reserved.