Combined web distortional and lateral-torsional buckling of partially restrained I-section beams

Abstract

This paper proposes an analytical model for analysing the interaction between web distortion and lateral-torsional buckling of partially restrained I-section beams under transverse distribution loading. The analysis is performed by using Rayleigh-Ritz method, in which the web is modelled as a plate and the two flanges are treated as two independent beams. The total potential energy functional of the system is derived using three-dimensional strain-displacement relationships in solid mechanics. The critical buckling stress and critical buckling moment of the I-section beam are calculated by solving a 3 × 3 eigen-matrix equation. For the validation of the present model the finite element analysis using three-dimensional shell elements is also carried out. The comparison between the analytical and numerical results demonstrates the correctness and rigorous of the proposed analytical model despite its simplicity.