AbstractThe present paper reports in-depth experimental and numerical studies of the cross-sectional behavior and resistances of austenitic stainless steel welded I-sections under combined compression and major-axis bending moment. A testing program was first performed, which employed two austenitic stainless steel welded I-sections and included initial local geometric imperfection measurements and 10 major-axis eccentric compression tests. Following the testing program, a numerical modeling program was conducted, where finite-element models were developed and validated against the test results and then employed to conduct parametric studies to generate further numerical data over a wide range of cross-section dimensions and loading combinations. On the basis of the obtained test and numerical data, the accuracy of the design interaction curves given in the European code and American design guide for austenitic stainless steel welded I-sections under major-axis combined loading was evaluated. The evaluation results generally indicated that the codified design interaction curves yield excessively conservative cross-section resistance predictions, mainly due to the conservative end points, as determined without considering material strain hardening. Finally, new design interaction curves were proposed through adopting the European code design interaction curves anchored to more accurate end points, as calculated with rational exploitation of material strain hardening by the continuous strength method. The new design interaction curves were found to offer significantly improved design accuracy than their codified counterparts. The reliability of the new design interaction curves was confirmed by means of statistical analyses.