Seismic performance of innovative hybrid precast reinforced concrete beam-to-column connections

Precast construction of structural buildings requires connection techniques that can shorten the process using only simple on-site activities while still guaranteeing adequate strength, energy dissipation, stiffness, and ductility. The construction methods should decrease the use of formwork and temporary bracing to save time and costs. In this study, innovative hybrid connections using steel tubes, steel plates, and steel couplers to join beams and columns were proposed and tested under reversed cyclic loading. Five half-scale samples of the hybrid precast joints, including the monolithic and precast joints, were examined to evaluate the seismic performance of the connections. The hybrid connections showed better performance in terms of load, displacement, drift ratio, ductility, strength, stiffness, and energy dissipation compared to a monolithic connection. The drift ratio, moment capacity, strength, and total cumulative energy dissipation of the hybrid connections were higher by 12.5-50.0%, 34.68-59.57%, 35.0-60.0%, and 50.99-331.32%, respectively, when compared with a monolithic connection. The failure modes of the hybrid connections were governed by yielding steel reinforcement, yielding steel plate, and flexural failure, with less extensive damage compared to the monolithic joint. The hybrid connections were effective in shifting the plastic hinges to outside the connection zone. Therefore, the hybrid connections can be used in high seismic zones because the superior performance results meet the requirements of the seismic codes.