Numerical Study and Design Method for Lateral Torsional Buckling of High-Strength Steel Beams

Given the increasing use of high-strength steels in building constructions, the stability design of high-strength steel beams has become a crucial consideration. However, the current standards of various countries are based on analyses and fittings derived from conventional steel, rendering them unsuitable for high-strength steel. Moreover, existing research indicates that these standards underestimate the ultimate load-bearing capacity of high-strength steel beams. A finite element model was established to investigate lateral torsional buckling in high-strength steel beams. The obtained results were then compared with test results from experiments conducted on Q460GJ and Q690 steel beams. The reliability and accuracy of the established finite element model were validated. Through parametric studies, the impact of depth-to-width ratio, boundary condition, and steel grade on the stability coefficient was evaluated. It was observed that at the same non-dimensional slenderness, an increase in the depth-to-width ratio or a reduction in support constraints led to a decrease in the stability coefficient. It should be noted that the steel grade had little effect on the stability coefficient. Comparisons with the current steel structure design codes, such as EN1993-1-1, GB50017-2017, JGJ/T483-2020, and ANSI/AISC360-22 revealed an underestimation of the stability coefficient for clamped high-strength steel beams under uniformly distributed loads. Based on finite element simulations, stability coefficients for high-strength Q460, Q690, and Q960 clamped beams were determined. Similar to the stability coefficient proposed in GB50017-2017 for the lateral buckling stability design of steel beams, a lateral buckling stability coefficient for high-strength steel clamped beams subjected to uniformly distributed loads was proposed.