Experimental and Numerical Investigations of S690 High-Strength Steel Welded I-Sections under Combined Compression and Bending

This paper presents a comprehensive experimental and numerical investigation into the cross-section behavior and resistances of S690 high-strength steel welded I-sections under combined compression and bending moment. First, a testing program was carried out and included initial local geometric imperfection measurements and ten major-axis and minor-axis combined loading tests. The testing program was followed by a numerical modeling program, where finite-element models were developed and validated against the test results and then used to perform parametric studies to generate further numerical data over a wide range of cross-section dimensions and loading combinations. On the basis of the test and numerical data, the codified interaction curves for S690 high-strength steel nonslender welded I-sections under combined loading, as used in Europe, Australia, and the US, were evaluated. The evaluation results revealed that (1) the European code yields accurate resistance predictions for S690 high-strength steel Classes 1 and 2 welded I-sections under both major-axis and minor-axis combined loading but underestimates the resistances for their Class 3 counterparts, (2) the Australian standard leads to a high level of conservatism for S690 high-strength steel nonslender welded I-sections under combined loading, and (3) the American specification can well predict the resistances for S690 high-strength steel nonslender welded I-sections under major-axis combined loading but results in conservative resistance predictions for those under minor-axis combined loading. The reliability of the codified interaction curves was also evaluated by means of statistical analyses.