Flexural behaviour of 7A04-T6 high-strength aluminium alloy SHS and RHS beams under moment gradient

High-strength aluminium alloys would further reduce the cross-section dimensions, and consequently avoid inaccessible extrusion process for great cross-section members and accelerate the construction speed in comparison with normal-strength aluminium alloys. 16 tests on extruded square and rectangular hollow sections (SHS/RHS) subjected to three-point bending were carried out in this paper, with width-to-thickness ratios ranging from 6.07 to 18.22. The material properties, failure modes, moment resistance, end rotation capacity and strain response of specimens were fully reported. Finite element (FE) models were developed and validated against the experimental results. Upon validation, an extensive parametric study over a wide range of cross-sectional slenderness and width-to-height ratios was performed. The experimental and numerical results were used to evaluate the applicability of the current design provisions in Chinese, European and American codes, as well as the proposed continuous strength method (CSM) extended to the 7A04-T6 high-strength aluminium alloy which is not included in the codes. The results showed that the predictions yielded by the three standard design methods were relatively conservative, while significantly improved resistance predictions were obtained through application of the revised CSM-based approach. The four design methods were safely feasible for the design of 7A04-T6 high-strength aluminium alloy SHS and RHS beams according to the reliability analysis.