Ultimate moment capacity of bolted joint for cold-formed aluminium back-to-back channel sections

Abstract

Cold-formed aluminium (CFA) channel sections are gaining popularity in structural applications as a lightweight and corrosion-resistant alternative to carbon steel, especially in coastal and aggressive environments. However, their effective use depends critically on the performance of their connections. This research investigates the structural behaviour of bolted moment connections in back-to-back CFA channel sections. Key factors such as web buckling, shear lag, and bending shear interaction were identified as influencing the ultimate moment capacity of these joints. An extensive numerical study of 1008 validated finite element (FE) models was conducted using ABAQUS. Moreover, validation was carried out based on experimental tests available in the literature. The Direct Strength Method (DSM) showed noticeable deviations from FE results in several cases, highlighting the limitations of DSM when applied to CFA sections. A parametric analysis was performed to examine the influence of cross-sectional size, thickness, web holes, and aluminium alloy grade and temper. Based on these findings, a new predictive equation is proposed for the reduced moment capacity of CFA back-to-back channel sections. The equation was rigorously assessed for reliability and accuracy, and it provides a practical tool for engineers designing CFA portal frame connections. .