Experimental and numerical investigations of press-braked stainless steel channel section beam-columns

Abstract

The buckling behaviour and resistances of press-braked stainless steel channel section beam-columns under combined compression and minor-axis bending have been studied in the present paper through laboratory testing and numerical modelling. The testing programme adopted two press-braked stainless steel channel sections and included initial global and local geometric imperfection measurements and ten beam-column tests. Two types of failure mode, namely ‘C’-orientation buckling (indicating that failure specimens buckled towards the web) and ‘reverse C’-orientation buckling (signifying that failure specimens buckled towards the flange tips), were observed upon testing. The testing programme was followed by a numerical modelling programme; finite element models were developed and validated against the test results and then adopted to perform parametric studies to generate further numerical data on press-braked stainless steel channel section beam-columns over a wide range of cross-section dimensions, member effective lengths and loading combinations. The obtained experimental and numerical data were employed to assess the accuracy and consistency of the relevant codified design rules for press-braked stainless steel channel section beam-columns, as given in the European code, American specification and Australian/New Zealand standard. The results of assessment revealed that the European code yields many unsafe resistance predictions for Class 1 and 2 press-braked stainless steel channel section beam-columns but overly conservative resistance predictions for Class 3 press-braked stainless steel channel section beam-columns, although the resulting overall design accuracy is good, but with a high level of scatter of the resistance predictions. Compared with the European code, the American specification and Australian/New Zealand standard result in slightly more accurate resistance predictions for press-braked stainless steel channel section beam-columns with buckling in the ‘C’ orientation, but lead to significantly more conservative predicted resistances for press-braked stainless steel channel section beam-columns with buckling in the ‘reverse C’ orientation. In terms of the design consistency, the American specification and Australian/New Zealand standard were shown to result in more consistent resistance predictions (regardless of cross-section dimensions and buckling orientations) than their Eurocode counterpart.