# Experimental Study of a New Precast Prestressed Concrete Joint
## 1 Introduction
However, the introduction of prestressing on the precast concrete structure allows for the full use of the tensile and compressive strength of the member, improves the shear capacity of the structure, reduces the section height of the member, reduces the deformation, and ensures good crack closure and deformation recovery performance of the structure. [PERSON] et al. [18] studied the precast beam-column joints of partially unbonded prestressing tendons where the prestressing tendons were non-bonded within a certain range of the joint zone and the beam end. The results showed that the self-recovery ability of the joints was strong and the shear capacity was improved. The seismic behavior of prestressed prefabricated beam-column joints with energy-dissipation steel bars was investigated by [PERSON] et al. [19] and [PERSON] et al. [20]. The self-recovering force was shown to be provided by the prestressing tendons and the energy consumed by the ordinary steel bars. [PERSON] et al. [21], [PERSON] et al. [22], and [PERSON] et al. [23] proposed an unbonded post-tensioned precast concrete structure using dampers to supplement energy dissipation. The research of post-tensioned precast beam-to-column connections was conducted by [PERSON] et al. [24], and the performance of the joints at different stress levels through experiments were analyzed. [PERSON] et al. [25] conducted pseudo-dynamic and quasi-static tests on a two-story precast prestressed concrete frame. The seismic performance of the post-tensioned prestressed joints was determined by performing reversed cyclic loading tests on two specimens with bonded tendons and two specimens with unbonded tendons by [PERSON] et al. [26]. The test results showed that the test piece consumed less energy, but the residual deformation was smaller, and it had better recovery performance. [PERSON] et al. [27] studied the performance of structures with U-shaped prestressed steel strands, precast columns, precast slabs, and topping concrete by testing three interior and three exterior joint specimens. [PERSON] et al. [28; 29] conducted reversed cyclic loading tests on precast prestressed concrete frame beam-column joints with different lengths of service hole. A steel-strand-anchored precast frame joint with embossed anchors was proposed by [PERSON] et al. [30]. [PERSON] et al. [31] introduced a ductile moment-resisting connection intended for high-intensity seismic zones. [PERSON] et al. [32] studied the parameters of a reinforced-concrete-emulated beam-column connection of a precast concrete moment frame with a U-shaped beam shell at the end of the beam. [PERSON] et al. [33] proposed three plastic hinge relocation methods to improve the earthquake resistance of emulative precast concrete beam-column connections using PC (precast concrete) U-shell beams. These studies show that the prestressing enhances the self-recovery ability of the joints, but some post-tensioned prestressed joints have poor energy dissipation capacity. Moreover, the connection of precast prestressed members, the interface treatment of the new-old concrete interfaces, the concrete strength, and their influences on the seismic performance of joints were not discussed comprehensively. Therefore, a precast prestressed concrete frame structure was studied in this paper. The reversed cyclic loading testing of three joints with different parameters was performed to observe the behavior and to obtain the hysteresis curve and skeleton curve of the joints. The stiffness, bearing capacity, ductility, and energy dissipation capacity of the joints were analyzed to investigate whether the seismic performance of the precast prestressed concrete frame joints met the requirements of the equivalent monolithic system. The influence of concrete strength in the keyway area on the performance of precast prestressed concrete joints was investigated. The reliability of the interface treatment method of the new-old concrete interface was studied. The force mechanism of precast prestressed concrete joints was analyzed.