Local-flexural interactive buckling behaviour and resistances of high-chromium stainless steel slender welded I-section columns

The present paper describes a comprehensive experimental and numerical study of the local-flexural interactive buckling behaviour and compression resistances of slender welded I-section columns made of a new grade EN 1.4420 high-chromium stainless steel. A testing programme, adopting two high-chromium stainless steel slender welded I-sections - I-150 x 150 x 5 and I-200 x 100 x 5, was firstly conducted and included ten pin-ended column tests as well as supplementary initial global and local geometric imperfection measurements on the column specimens. The testing programme was followed by a numerical modelling programme, where finite element models were developed and validated against the test results, and then employed to perform parametric studies to generate further numerical data over a wide range of cross-section dimensions and member effective lengths. The obtained test and numerical results were adopted to evaluate the applicability of the codified design rules for normal stainless steel slender welded I-section columns failing by local-flexural interactive buckling, as set out in the European code and American design guide, to their new high-chromium counterparts. Specifically, the European code adopts the design concept of using effective width method to account for local buckling and buckling curves to consider global buckling, and was shown to yield accurate, consistent and safe interactive buckling resistance predictions when used for the new high-chromium stainless steel slender welded I-section columns. The American design guide employs net section reduction factors to consider local buckling in slender plate elements, based on which a reduced design flexural buckling stress is determined; the predicted interactive buckling resistances, compared with the test and numerical failure loads, indicated a marginally high degree of conservatism and scatter of the American design guide. It can thus be concluded that (i) the design rules given in the European code and American design guide can be safely applied to the new high-chromium stainless steel slender welded I-section columns failing by local-flexural interactive buckling, and (ii) the European code results in more accurate and consistent predictions of interactive buckling resistance than the American design guide. The reliability of the codified design rules, as given in the European code and American design guide, was confirmed by means of statistical analyses.