Nonlinear finite element analysis to evaluate lateral torsional buckling moment of elliptical cellular steel beams

Abstract

In evaluation the lateral torsional buckling moment of Elliptical Cellular beams, it cannot be accurately calculated using a simple model because the sectional properties of the Elliptical Cellular beam are not constant along the beam length. Consideration of sectional properties at the web-post section will certainly lead to unconservative results, while consideration of sectional properties at the web-opening section is also unreal and yield conservative design. Therefore, the main objective of this paper is to present the guideline to evaluate the lateral torsional buckling moment capacity of Elliptical Cellular beam for conservative and more precise results. The study has been performed throughout finite element analysis in both elastic and inelastic buckling behavior subjected to equal beam-end moments. More than 15 sections, 120 of beam models were simulated and analyzed with verified finite element modelling by using shell elements. The results of this study show that calculation the lateral torsional buckling moment of Elliptical Cellular beam with the original equation given in AISC standard using sectional properties at the web-post section gives unsafe results with approximately 5% error in elastic range and up to 20% error in inelastic and plastic range. Nonetheless, evaluation the lateral torsional buckling moment by using the proposed reduction factor has yielded the conservative results, yet more precision, more economic and less distribution of the results than the evaluation using sectional properties at the web-opening section.