Shear behaviour and design of roll-formed aluminium beams

Abstract

This paper establishes a shear design for plain roll-formed aluminium beams with unlipped C, lipped C, and Zed sections incorporating downturn lips. The shear response of these thin-walled members is characterised through a coordinated experimental and nonlinear finite element analysis, employing both three-point and dual-actuator loading to explicitly isolate pure shear behaviour. A large-scale parametric investigation comprising 540 finite element models is conducted to investigate elastic shear buckling and ultimate shear resistance over a range of geometries, web depths, thicknesses and material grade at a constant aspect ratio of 1.0. The results reveal governing shear that is not captured by existing design standards. Comparisons with AS/NZS 1664.1, Eurocode 9, and the Direct Strength Method of AS/NZS 4600 demonstrate systematic conservatism and inconsistent trend prediction. The unified proposed model improves the accuracy of bending strength predictions by eliminating systematic bias, reducing the mean prediction ratio from 1.11 to 1.00. The coefficient of variation is also reduced from 0.128 to 0.037 across 270 specimens. The maximum reduction in prediction error for the individual specimen reaches up to 26%. This enhanced accuracy enables more efficient designs through reduced conservatism, facilitating material savings and more consistent safety margins while maintaining structural reliability.