The objective of this study is to propose a new strength formula for beam-columns made of H-SA700 High-strength steel. The elastic lateral torsional buckling strengths of beam-columns subjected to axial force and bending moment at both ends are calculated by using the Galerkin method. In addition to the elastic lateral torsional buckling load, in-plane elastic limit strengths are calculated. As the analytical parameters, slenderness ratio and moment ratio of the smaller to the larger end moment are selected, and the analytical results are shown in interaction relationship between end moment and axial force. Examining the results, we proposed the strength formula basically composed of two equations that mean the strengths of lateral torsional buckling and elastic limit strength.
