Local buckling behaviour of 7075-T6 high strength aluminium alloy H-section beams under concentrated loads: Testing, modelling and design

Abstract

In recent years, a new generation of 7 series high strength aluminium alloys were developed and widely used in practical engineering due to their excellent performance, and their tensile yield strength can be approximately 80 % (or more) higher than that of traditional aluminium alloys. One obvious application for such new material is in H-section beams with slender webs, where the local buckling behaviour should be investigated for safety and economical design. However, no research work was reported investigating the local buckling behaviour of such 7 series high strength aluminium alloy bending members. This issue is addressed herein. A total of seven 7075-T6 high-strength aluminium alloy extruded H-section beams were tested under concentrated loads, including four specimens with mid-span stiffeners and three ones without mid-span stiffeners. A finite element (FE) model was developed and validated against the test results. A comprehensive parametric analysis including 163 FE models was performed to examine the influences of the critical parameters on the ultimate strength of such members. Following this, the obtained test and numerical results were utilised to evaluate the accuracy of the design methods in EN 1999–1–1: 2023 (2023), GB 50429–2007 (2007), American Aluminum Design Manual (2020). The comparison results indicated that the existing design methods provide conservative predictions for determining the ultimate strength of high strength aluminium alloy H-section beams. New design methods were therefore proposed by modifying the original design equations. A reliability analysis was then performed, indicating that the modified formulas can closely predict the ultimate strength of such members.