Influence of overhang length on LTB behavior of compact doubly-symmetric steel I-beams

Abstract

The present study pertains to elaborating on the effects of overhang lengths beyond end supports on elastic and inelastic Lateral Torsional Buckling behaviour of doubly-symmetric steel I-beams. Finite element analyses were performed on compact sections to avoid the local (plate) buckling and beam distortions to interfere with the overall beam behaviour. Accuracy of the numerical analyses was verified with the help of existing experimental results. Subsequent to this verification, 120 beams with five different compact I-sections, four different overhang lengths, two different unbraced span lengths and three different sweep values were analysed. The numerical buckling moments of the beams with considerable overhangs were established to remain well below the respective estimates from AISC 360-16 formulation. The difference between the numerical and analytical values stems from the inability of the formula to reflect the lateral deflections of overhangs, i.e. predicating on full lateral restraint beyond unbraced spans. The study also indicated that flexural rigidities and moment capacities of beams increase with increasing overhang lengths. The increase in the buckling moment resistance in elastic and inelastic LTB were established to reach 11 and 16%, as the overhang-to-total length ratio increases from 0 to 0.30 for various sweep values.