Stability and design of high-strength aluminium alloy RHS members under eccentric compression

The structural behaviour of the 7A04-T6 high-strength aluminium alloy rectangular hollow section (RHS) members was investigated through an eccentric compression test programme presented in this paper. The programme encompassed eight RHS members with profiles of 60 x 30 x 3 (in mm), and cross-sections of Class 2 similar to 4 were considered, involving initial geometric imperfection measurements and pin-ended beam-column tests. Finite element (FE) models were developed and validated with respect to the load - lateral deflection curve and failure mode. These models were then employed in a series of parametric studies designed to investigate the effects of member slenderness ratios, cross-section dimensions and loading combinations. An assessment of the Chinese, European and American design codes against the experimental and simulated dataset revealed that the Chinese and European codes typically yielded conservative predictions for the buckling load-carrying capacity, whereas the American code yielded slightly unsafe predictions. A set of modification strategies shown to improve the design accuracy and simplify effective section calculation were proposed accordingly, including the addition of interaction buckling factors to the three codes as well as the extension of the direct strength method (DSM) and continuous strength method (CSM) within the framework of Chinese code. The predictions corrected by these strategies showed improved agreement with the test and FE results, exhibiting an acceptable level of reliability and dispersion.