Elastic Lateral Torsional Buckling of Simply Supported Beams under Concentrated Load and Linear Moment Gradient

Lateral torsional buckling is a limit state for I-shaped steel beams that may often be a controlling issue in structural steel design. When these members are not appropriately braced so as to prevent lateral deformations and torsion, they are subjected to risk of failure by lateral torsional buckling before reaching their ultimate capacity. This paper investigates elastic lateral torsional buckling of simply supported I-shaped steel beams under concentrated load and linear moment gradient using design standards and codes, approaches from the literature and finite element analysis. Several unbraced member lengths and end moment values are taken into account to compare and evaluate these approaches in terms of elastic critical moment and end moment ratios. Analysis results show that lateral torsional buckling is a crucial stability problem for I-shaped steel members that are under flexure and it is reflected with adequate safety in the design codes and standards considering finite element analysis outcomes.