ABSTRACT
Modern design methods of steel beam-columns, such as the General Method of Eurocode 3, utilize solutions of the elastic flexural-torsional buckling of beam-columns that is limited to the elements of bisymmetric I-shape sections. Such solutions cover the whole domain of the possible design situations in which there are different proportions between the maximum bending moment and the compressive axial force. The proposed paper addresses a more general case of beam-columns of monosymmetric I-shape sections. Different analytical elastic buckling solutions existing in literature are studied in reference to the flexural-torsional buckling of monosymmetric I-shape section members. The solutions presented in literature are based on different assumptions, namely they may account for the secondary flexural and torsional effects on the critical state, or may neglect entirely the effect of prebuckling state of deformations on the critical state, or may neglect only the second order torsional state of deformation. In particular, when the flange of a greater sectional area is more stressed in compression, the flexural-torsional buckling compressive force may exceed its critical value since the bending moment of a non-vanishing value ensures the stable condition of beam-columns. Analytical solutions are compared with numerical results from the LTBeamN software conventionally utilized in practice. Conclusions related to analytical results are drawn.
