Experimental and numerical study of press-braked S690 high strength steel slender channel section columns prone to local–flexural interactive buckling

Abstract

This paper reports an experimental and numerical investigation into the local–flexural interactive buckling behaviour and resistance of press-braked S690 high strength steel slender channel section columns. An experimental programme was firstly conducted and included initial geometric imperfection measurements and twelve pin-ended column tests. Interaction between local buckling and flexural buckling was observed for all specimens upon testing and discussed in detail. The experimental programme was accompanied 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 data were used to assess the accuracy of the codified design rules for press-braked S690 high strength steel slender channel section columns failing by local–flexural interactive buckling, as set out in the European code, North American specification and Australian/New Zealand standard. The assessment results revealed that the European code leads to excessively conservative and scattered resistance predictions, while the North American specification and Australian/New Zealand standard result in a higher level of design accuracy and consistency, but still with many conservative resistance predictions for columns with short to intermediate lengths. Finally, a new design approach was proposed and shown to yield substantially more accurate and consistent resistance predictions for press-braked S690 high strength steel slender channel section columns over the design codes.