Lateral Buckling Strength of Simply Supported LiteSteel Beams Subject to Moment Gradient Effects

Abstract

The flexural capacity of a new cold-formed hollow flange channel section known as LiteSteel beam (LSB) is limited by lateral distortional buckling for intermediate spans, which is characterized by simultaneous lateral deflection, twist, and web distortion. Recent research has developed suitable design rules for the member capacity of LSBs. However, they are limited to a uniform moment distribution that rarely exists in practice. Many steel design codes have adopted equivalent uniform moment distribution factors to accommodate the effect of nonuniform moment distributions in design. But they were derived mostly based on the data for conventional hot-rolled doubly symmetric I-beams subject to lateral torsional buckling. The effect of moment distribution for LSBs and the suitability of the current steel design code rules to include this effect for LSBs are not yet known. This paper presents the details of a research study based on finite-element analyses (FEAs) of the lateral buckling strength of simply supported LSBs subject to moment gradient effects. It also presents the details of a number of LSB lateral buckling experiments undertaken to validate the results of FEAs. Finally, it discusses the suitability of the current design methods and provides design recommendations for simply supported LSBs subject to moment gradient effects.