Numerical modelling of extruded aluminium alloy T-stubs connected by swage-locking pins: FE validation and parametric study

Abstract The structural behaviour and design of extruded aluminium alloy T-stubs connected by swage-locking pins are studied in the present paper. Finite element (FE) models were developed and validated against test results on extruded aluminium alloy T-stubs connected by swage-locking pins carried out in the companion paper [1]. Prior to the numerical modelling of the T-stubs, refined and simplified FE models of swage-locking pins were developed, and evaluated by comparing with experimental results; the refined model explicitly takes into account the geometries and load-slip behaviour of the swage-locking pins and provides accurate predictions of the test results, while the simplified model is developed through application of a four-step calibration methodology, and has been shown to provide similar accuracy with the refined model, but with significantly reduced computational time. Upon validation, an extensive parametric study was performed to investigate the effect of key parameters, including the preload in the swage-locking pins, the pin diameter, the fillet radius at the web-to-flange junction and the pitch distance between pins, on the structural performance of the T-stubs. The numerically derived results were also compared with the resistance predictions according to the design method in EN 1999-1-1 (EC9). The comparisons indicated that the EC9 provides safe-sided, yet somewhat conservative and scattered, resistance predictions for extruded aluminium alloy T-stubs connected by swage-locking pins, owing principally to inaccurate predictions of the distance between two plastic hinges formed in the T-stub flange. A new design method was proposed for more accurate predictions of the plastic hinge distance, resulting in improved accuracy and consistency over EC9 for calculating the resistance of extruded aluminium alloy T-stubs connected by swage-locking pins.