Shear behaviour of roll-formed aluminium channels with web holes considering shear span aspect ratio of 2.0

Roll-formed aluminium (RFA) channel sections are widely used as structural components in corrosive and high-moisture environments, where web holes are often required for service integration. When the available web depth is limited, elongated web holes are generally preferred over conventional circular holes. However, the presence of such holes can considerably reduce the shear strength of the section. To counteract these effects and enhance structural performance, stiffeners are commonly provided around the edges of the holes. However, research on the shear behaviour of RFA channel section with both unstiffened and stiffened web holes remains limited. This study examines the shear behaviour and strength of RFA channels considering shear span aspect ratio (AR) of 2.0, considering various web hole shapes and sizes. Finite element (FE) models were developed and validated against existing experimental data. An extensive parametric investigation involving 972 FE models was carried out by varying channel cross-sections, hole geometries, and stiffener lengths. The obtained results were assessed against existing design provisions. The Direct Strength Method (DSM) was found to be conservative by an average of 8% for channels with plain webs, and by an average of 10% and 14% for channels having webs with unstiffened circular and elongated holes, respectively. As a result, new DSM-based design equations were proposed, including equations for elastic shear buckling coefficients, shear yielding resistance, and shear reduction and enhancement factors. Reliability analyses were conducted and confirmed that the proposed equations provided accurate predictions of the shear strength of RFA channel sections with both stiffened and unstiffened web holes.