Structural behaviour and design of press-braked S690 high strength steel channel sections under combined compression and minor-axis bending

This paper presents experimental and numerical investigations into the cross-sectional behaviour and resis-tances of press-braked S690 high strength steel channel sections under combined compression and minor-axis bending. An experimental programme was firstly conducted and included initial local geometric imperfection measurements and ten minor-axis eccentric compression tests. 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 expand the test data pool over a wider range of cross-section dimensions and loading combinations. The obtained test and numerical data were then used to assess the relevant codified design interaction curves, as provided in the European code, North American specification and Australian/New Zealand standard. The assessment results revealed that all the codified design interaction curves led to excessively conservative and scattered resistance predictions for press-braked S690 high strength steel channel sections under combined compression and minor-axis bending, mainly owing to the conservative linear shapes and inaccurate end points. Finally, a new design interaction curve, with more accurate end points and nonlinear shape, was proposed and shown to offer more accurate and consistent resistance predictions than the codified design interaction curves.