Experimental and numerical investigation of sleeved bolted T-stub connections with thin-to-medium plates

Abstract

Bolted T-stub connections require adequate strength and ductility to ensure reliable performance under extreme loading conditions. In this study, the influence of sleeve systems on the structural behaviour of T-stub connections is experimentally and numerically investigated. A total of 21 specimens with three flange thicknesses (8, 12, and 15 mm) were tested without sleeves and with obround wave (OBW) and circular wave (CW) sleeve configurations under monotonic tensile loading. The force-displacement response, failure mechanisms, and deformation characteristics were examined, and finite element (FE) models were developed and validated using the experimental data. Following validation, an extensive parametric study comprising 50 FE models was conducted to evaluate the influence of sleeve height, thickness, and amplitude on strength, ductility, and failure modes. The results show that sleeve installation significantly enhances load-carrying capacity, deformation capacity, and post-peak stability across all flange thicknesses. Failure analysis reveals that thin-flange specimens are governed by flange yielding, whereas medium-flange specimens exhibit combined flange yielding and bolt necking accompanied by progressive sleeve crushing. The validated FE models accurately capture the observed structural response and damage evolution. Overall, the proposed sleeve system offers a reliable and practical solution for improving the structural performance of bolted steel connections under monotonic tensile loading.