BEAM-E1EMENT-BASED ANALYSES OF LOCALLY AND DISTORTIONALLY BUCKLED COLUMNS

摘要

A theory is described in the paper which considers local and distortional buckling effects in beamelement-based large displacement analyses. The theory treats the effects of local and distortional buckling as merely reductions of the member's rigidities against axial shortening, flexure and warping. The reduced rigidities, referred to as tangent rigidities, are then incorporated into beam-elementbased analysis programs by replacing the unreduced terms by tangential terms when formulating tangent stiffness matrices and internal force vectors. Nonlinear analyses are performed to validate the accuracy of this theory. Two types of I-section with different member lengths are considered, subjected to pure compression. The sections are designed such that local and/or distortional buckling occur before member buckling so that failure occurs by interaction of these modes. Elastic and inelastic analyses are presented, and comparisons are made with ABAQUS shell finite element results. Good agreement is achieved for both ultimate loads and load-deflection curves. The theory allows complex problems, which ordinarily require computationally demanding shell finite element discretisation, to be solved using simple beam elements at a fraction of the computing cost otherwise required.