Improving the ConXL connection behavior using T-Stub fragments

This study investigates the seismic performance of ConXL moment connections, focusing on the role of T-Stub fragments configurations in enhancing structural behavior under cyclic loading. The original ConXL design prioritizes moment transfer through bolts and collar components but lacks a protected area for plastic hinge formation, which is essential for energy dissipation without damaging the Complete Joint Penetration (CJP) weld. This limitation can compromise the connection's performance under seismic conditions. The revised system introduces T-Stub fragments, which modify the stress distribution and moment-resisting behavior by adding stiffness and deformation capacity to the connection. This modification improves the connection's resistance to seismic forces and enhances its endurance under cyclic loading. The T-Stub fragments serve two primary functions: first, they guide the plastic hinge to a safer location, preventing plasticity in critical zones such as the beam to-collar flanges welds, reducing the risk of brittle failure, and improving ductility. Second, they help the collar flanges transmit stress caused by cyclic loading to the collar corners, optimizing stress distribution and increasing the connection's energy dissipation capacity. The optimal model, TXL300-15, shows an 18% improvement in energy dissipation and a 24% increase in ultimate moment capacity compared to the conventional ConXL connection with an RBS. These findings highlight the enhanced seismic resilience, energy absorption, and structural stability of the modified ConXL connection, making it more effective at resisting seismic forces.