Lateral–Torsional and Distortional Buckling of I-Shaped Welded Steel Girders

Abstract

This paper presents the experimental testing and numerical simulations of four full-scale I-shaped welded steel girders to examine their lateral–torsional buckling (LTB) and lateral–distortional buckling (LDB) behaviors and evaluate the adequacy of the associated provisions in North American steel design standards. The test specimens and setup are first presented, followed by the experimental test results used to assess the inelastic LTB and LDB behaviors. A corroborated finite-element model is then used to further evaluate the influences of web distortion on the flexural response of the girders and to assess the adequacy of the design provisions when applied to girders with web depth-to-thickness ratios close to the Class 2/3, or compact/noncompact boundary (i.e., h/w≈90). The results show that LDB, in combination with inelastic LTB, influences the flexural response and resistance of welded steel girders with webs of this slenderness. Furthermore, the North American steel design provisions may overestimate the flexural moment resistance of such girders.