Formulation of the critical lateral buckling moment of steel beams under asymmetric loadings

This article investigates the elastic lateral buckling of unrestrained beams. According to the design code, the beam strength is function of the lateral buckling moment. In literature, the buckling moment is function on bending distribution, load height position and the monosymmetry cross section shape. The coefficients C1−C3 are affected to these parameters in the solution. However, no formula or table is available for the case of beams subjected to nonsymmetrical loading. This article proposes an analytical formulation for the critical moment for lateral–torsional buckling of steel beams under asymmetrical loading. The expression of the critical buckling moment, which is based on the Galerkin method, as well as the coefficients (3C) that affect the intensity of the critical moment for asymmetric loading cases, are then proposed. The present method is compared to numerical simulations and available solutions in literature. The results obtained allowed concluding that in the case of asymmetrical loading, the application of the loading cases proposed by the CCM 97 remains unsafe.