Influence of connection configuration on the punching resistance of CFST column–RC slab systems under eccentric loading

This study investigates the punching shear behaviour and failure mechanisms of concrete-filled steel tube (CFST) column reinforced concrete (RC) slab connections subjected to eccentric loading through an integrated experimental and numerical approach. Twelve specimens with different connection details, including welded bars, bolted connections, and C-shaped embedded bars, were tested to assess the influence of connection configuration, reinforcement arrangement, and bolt embedment length on structural performance. The experimental results showed that welded and bolted connections markedly enhanced cracking load, ultimate capacity, and ductility compared with the control specimen, while the combined welded–bolted configuration achieved the most favourable overall response. The study enhances the understanding of load transfer mechanisms in CFST–RC slab connections. Incorporation of welded bars and bolts substantially enhanced the connection stiffness, strength, and ductility. The two-row welded bar configuration showed significant improvements in load-carrying capacity, while the hybrid welded–bolted connection demonstrated the highest overall performance.