Experimental and numerical study on lateral-torsional buckling of singly symmetric Q460GJ steel I-shaped beams

This paper presents experimental and numerical studies on the lateral-torsional buckling behaviour of singly symmetric I-beams fabricated of Q460GJ structural steel. A total of six singly symmetric I-shaped beams, with various slenderness and height-width ratios, were designed with lateral restraints at the mid-span and tested under concentrated point loads. Experimental results demonstrated that steel beams developed lateral-torsional buckling when subject to bending moment. Comparisons between experimental and calculated values according to relevant design codes indicate that most design methods underestimate the buckling moment of Q460GJ steel I-beams to a certain extent. Finite element models were established for steel beams and validated against experimental results. Parametric studies were carried out on the effects of slenderness and height-width ratio on the buckling moment of steel beams. Comparisons were also made between numerical results with design provisions in different codes of practice. Finally, recommendations were proposed for the design of singly symmetric Q460GJ steel beams against lateral-torsional buckling in accordance with experimental and numerical results.