Application of Generalised Beam Theory in Predicting Lateral Torsional Buckling of Thin-Walled Steel Sections

Abstract

Thin-walled structures are extensively used in buildings and automobile industries, and majority of the thin-walled structures are of lightweight cold-formed steel or aluminum. Structural elements such as cold-rolled profiles often fail in instability before even achieving their yield capacity/stress. Lateral Torsional Buckling (LTB) is a common instability failure in both thin-walled columns and beams. It is important to assess the structural response of this instability failure. The aim of this study is to derive cross-sectional properties and warping functions of a channel section required to predict the pure Lateral Torsional Buckling strength of light gauge steel channel sections using first order Generalised Beam Theory (GBT). Further, a first order GBT formulation and numerical analysis of cold-formed steel lipped channel beams (C80 × 40 × 10 × 1, C90 × 40 × 10 × 1, C100 × 40 × 10 × 1, C80 × 40 × 10 × 1.6, C90 × 40 × 10 × 1.6 and C100 × 40 × 10 × 1.6) of two different thicknesses (1 and 1.6 mm) and three different depths (80, 90, and 100 mm) subjected to uniform moment are undertaken to predict pure LTB and the critical buckling strength. The results show that theoretical buckling load values are 0.3% more than GBT buckling values and critical buckling values obtained from GBT shows little variation when distortions are involved in the final failure mode.