Effects of Shear on the Elastic Lateral Torsional Buckling of Doubly Symmetric I-Beams

Abstract

The theoretical lateral-torsional buckling solutions for I-beams utilized in many design specifications may the overestimate lateral torsional buckling (LTB) resistance when significant shear is present due to web distortion. This paper investigates the effects of shear on the elastic LTB of doubly symmetric steel I-beams through computational models. A parametric study was conducted considering a range of geometric parameters and loading conditions commonly found in design applications in buildings and bridges. The results show that shear can have a substantial impact on the LTB resistance under many practical design circumstances. The impact of shear on LTB is more significant for sections with larger web slenderness ratios and smaller depth-to-flange width ratios. Postbuckling shear resistance does not significantly impact the reductions in LTB resistance due to shear. A practical design method that accounts for shear effects on the LTB behavior in stiffened and unstiffened beams was proposed and verified by comparison with computational solutions. Design examples demonstrating the proposed method are provided.