Analytical study of the effects of the critical moment and brace rigidity on the lateral–torsional buckling of beams with discrete braces

Abstract This study develops a simplified analytical formulation for evaluating the minimum rigidity of discrete braces in relation to the lateral–torsional buckling of steel beams. The main contribution lies in deriving closed‐form expressions that incorporate key dimensionless parameters, offering a practical alternative to fully numerical approaches. The formulation is validated against finite element simulations performed with LTBeamN, demonstrating good agreement. The analysis is carried out under the assumptions of linear elastic behaviour, idealised support and bracing conditions, and doubly symmetric I‐sections, while residual stresses, imperfections and plasticity are not considered. Within these boundaries, the results provide valuable guidance for both the design and assessment of brace rigidity in steel structures.