Torsional Buckling Behavior and Resistances of S690 High-Strength Steel Welded Cruciform Section Columns

This paper presents experimental and numerical investigations into the torsional buckling behavior and resistances of S690 high-strength steel welded cruciform section columns. Experiments were first carried out and included initial torsional and global geometric imperfection measurements and 10 fixed-ended column tests. Subsequently, numerical modeling was conducted, where developed finite-element models were validated against the test responses and parametric studies were performed for generating additional numerical data. The test and numerical data were employed to evaluate codified design rules for S690 high-strength steel welded cruciform section columns failing by torsional buckling. The evaluation results revealed that design failure loads predicted by codified design rules were conservative and scattered, which was owing to the lack of proper consideration of the length-dependent characteristic of torsional buckling and duplicated reductions for local buckling and torsional buckling of slender cruciform section columns. Revised codified design rules were then proposed and resulted in improved design accuracy and consistency over their original counterparts. A relevant existing design method was also evaluated and provided overall accurate and consistent failure load predictions, although some were unsafe.