Cyclic Response Characteristics of SCC Extended End-Plate Reduced Web Section (RWS) Connections

This study investigates the cyclic behaviour of demountable steel–concrete composite extended end-plate reduced web section (RWS) connections for the first time, aiming to facilitate post-seismic beam replacement. A validated high-fidelity finite element (FE) model was developed to analyse 285 FE models, evaluating response characteristics based on the Ibarra–Medina–Krawinkler model. Key parameters, including the influence of composite action over the web opening, web opening diameter, and end-distance, were considered. Findings indicate that RWS connections with medium to large web openings experience cyclic strength degradation while remaining compliant with American and European seismic standards. Additionally, bolted shear studs yielded a more stable and predictable contribution to the connection’s strength up to 5%, outperforming traditional welded studs in consistency. This research emphasises the importance of aligning web opening size and location with capacity design ratios between connection components for acceptable seismic performance, proposing specific web opening sizes and locations to enhance structural resilience.