The second limit state for beams is Lateral Torsional Buckling, LTB for short. LTB occurs when the compression portion of a cross section is restrained by the tension portion and the deflection due to flexural buckling is accompanied by torsion or twisting. The way to prevent LTB is to have adequate lateral bracing at adequate intervals along the beam. The limit state is the interval of the bracing.
For each cross section, it is possible to compute limits for
LTB. The laterally unbraced length,









