Replaceable monolithic-like beam-to-beam precast connection for RC frames: Concept development and design procedure

This research presents the concept of a demountable monolithic-like precast connection system for modular construction of reinforced concrete (RC) frame structures. The proposed system provides excellent structural performance suitable for seismic regions, while offering rapid assembly and disassembly (replaceability) thanks to its innovative bolted detailing. Furthermore, it can be easily designed using conventional approaches. The replaceability of the proposed connection system enables both replacing structural members for repurposing and repairing the structure by replacing damaged members after an extreme load event (such as an earthquake or blast). To achieve monolithic-like behaviour, the longitudinal reinforcement ratio at the connection zone was kept similar with the monolithic counterparts by utilising the rivet head rebar approach. Also, to transfer the structural damage to the RC parts of the connection, the metallic components (plates and bolts) were designed to remain in their elastic zone. While previous preliminary studies demonstrated the efficiency of the proposed system for beam-to-column and column-to-base connections, this study will focus on beam-to-beam connections. An experimental study was conducted on 4 full-scale connections, consisting of two monolithic reference specimens and two precast specimens, under "flexural critical" and "shear critical" cases. The key performance parameters, including load bearing strength, initial stiffness, failure mode, ductility, energy dissipation capacity and equivalent damping were calculated. The results indicated that the proposed precast connection specimens exhibited a similar structural behaviour with their monolithic counterparts, and hence can be a viable alternative to traditional RC connections to promote sustainable construction in both seismic and non-seismic regions. Subsequently, a simple calculation approach was developed for the practical design of the components of the proposed connections system.