Experimental Study of Cold-Rolled Aluminium Channel Sections in Shear

Cold-rolled aluminium alloy channel sections have recently emerged as an alternative to conventionally extruded sections in the construction industry. These sections are manufactured using a cold-rolling process. Owing to their excellent corrosion resistance and high strength-to-weight ratio, these sections are increasingly used as primary load-bearing members such as roof purlins, floor joists, and rafters. However, under shear loading, cold-rolled aluminium channels may be particularly vulnerable to shear buckling due to their slender webs and relatively low elastic modulus. While extensive research has been conducted on the shear buckling behaviour and strength of cold-formed steel channel sections, studies focusing on the shear performance of cold-rolled aluminium alloy channels remain limited. To address this gap, this paper presents an experimental investigation conducted at the University of Sydney to examine the shear behaviour and ultimate shear strength of cold-rolled aluminium alloy channel sections subjected to predominantly shear loading. The experimental program comprised 18 tests on channel sections with web depths of 150 mm, 200 mm, and 250 mm, all with a uniform thickness of 2.5 mm. For each section depth, four shear span-to-depth aspect ratios of 1.0, 2.0, 2.5 and 3.0 were considered to capture the influence of aspect ratio on failure modes. A dual-actuator test apparatus was employed to apply predominantly shear forces while minimizing bending effects. The experimental ultimate shear capacities are compared with predictions from the Australian standard AS/NZS 1664.1 and American Aluminium Design Manual (AA 2015). The comparison demonstrates noticeable discrepancies between the current design rules and the test results, particularly in the inelastic buckling range. Based on these findings, a modified shear design procedure was also proposed to improve the prediction accuracy for cold-rolled aluminum channel sections. Consequently, the experimental results provide a benchmark for validating subsequent numerical models and form the basis for the development of improved shear design rules for coldrolled aluminium channel sections.