Inelastic Lateral Buckling of Beams

The problem of the inelastic lateral buckling of steel wide-flange beams is treated as an extension of the classical elastic buckling solution. The method is developed for the case of equal end-moments, about the major axis of the cross section, and for simply supported lateral and torsional boundary conditions. The influence of cooling residual stresses is considered in defining the boundaries of the elastic core. The lateral and the torsional stiffnesses are computed from the assumption that only the unyielded portions of the beams resist lateral buckling. The numerical work was performed for four representative wide-flange cross sections, and the results are represented as non-dimensional critical length-versus-critical moment curves. A simplified analytical method is given, and the analytical results are compared with two empirical design equations. A straight line transition equation is proposed in the report.