Effects of steel fibres and prestress levels on behaviour of newly proposed exterior dry joints using SFRC and CFRP bolts

Abstract

This study proposes a new type of dry exterior beam-column joints for precast moment-resisting concrete frames. This dry joint type uses steel fibre reinforced concrete (SFRC) and carbon fibre reinforced polymer (CFRP) bolts to improve the joint capacities. In addition, an analytical model to predict the load-carrying capacity of this precast joint type is also proposed. Five exterior beam-column joints were cast and tested under quasi-static cyclic loads until failure. The experimental results revealed that the use of SFRC significantly improved all the indices, including the load-carrying capacity, drift ratio, ductility, energy dissipation and stiffness. Also, the proposed joints outperformed the monolithic specimen in terms of load-carrying capacities, energy dissipation, and stiffness by 27–61%, 45–75%, and 27–55%, respectively. Particularly, the drift ratio of the proposed joints reached 3.5%, which satisfies the requirements for ductile joints to be used in earthquake-prone regions according to various standards. Finally, the proposed model yielded good predictions as compared to the experimental results with minor errors of approximately 0.9–2%. These exciting results indicate that the use of SFRC and CFRP bolts could help to avoid the challenging issue of corrosion in the conventional dry exterior joints and still ensure the sufficient requirements for reinforced concrete structures in non-seismic and seismic-prone areas.