A NEW APPROACH TO THE ELASTO-PLASTIC LATERAL BUCKLING STRENGTH OF BEAMS

This paper is concerned with an interpretation and analysis on the elasto-plastic lateral torsional buckling of beams in a simplified manner by means of catastrophe theory. The numerical analysis does not require having recourse to the ordinary nonlinear numerical procedures, but can be performed using a relatively small microcomputer.The proposed analysis takes into account the elasto-plastic behavior of the material, the geometric imperfections and the residual stresses. The ultimate strength of the beams is shown to be presented in the form of the bifurcation set in terms of the elasto-plastic buckling moment and the imperfection term that follows the 1/2 power law.It is found from the study that the characteristics of the elasto-plastic lateral torsional buckling may be identified as the fold catastrophe just like the case of centrally compressed columns.