On the Verification of Beams Subjected to Lateral Torsional Buckling by Simplified Plastic Structural Analysis

Abstract

AbstractPlastic structural analysis may be applied without any difficulty and with little effort for structural member verifications with regard to lateral torsional buckling of doubly symmetric rolled I sections. Suchlike analyses can be performed based on the plastic zone theory, specifically using finite beam elements with seven degrees of freedom and 2nd order theory considering material nonlinearity. The existing Eurocode enables these approaches and the coming‐up generation will provide corresponding regulations in EN 1993‐1‐14. The investigations allow the determination of computationally accurate limit loads, which are determined in the present paper for selected structural systems with different sets of parameters, such as length, steel grade and cross section types. The results are compared to approximations gained by more sophisticated FEM analyses (commercial software Ansys Workbench applying solid elements) for reasons of verification/validation. In this course, differences in the results of the numerical models are addressed and discussed. In addition, results are compared to resistances obtained by common design regulations based on reduction factors χlt including regulations of EN 1993‐1‐1 (including German National Annex) as well as prEN 1993‐1‐1: 2020‐08 (proposed new Eurocode generation). Concluding, correlations of results and their advantages as well as disadvantages are discussed.