Seismic behavior of precast prestressed concrete frame joints with different energy dissipation designs

The unbonded post-tensioned precast concrete joint based on PRESSS (Precast Seismic Structural System) technology has a simple form, convenient construction, and strong deformation-recovery properties. In this paper, both experimental and theoretical analysis methods were used to study the influence of different energy dissipation components on the seismic performance of the unbonded post-tensioned precast concrete joint. First, based on the existing 'plug-and-play' energy dissipation device, this paper improved its construction and designed two types of joints with new external energy dissipaters and internal energy-dissipating bars, respectively. Subsequently, low-reversed cyclic loading experiments were conducted. The two joints' seismic performance indexes, failure mode, hysteresis curve, skeleton curve, ductility coefficient, and residual deformation were compared and analyzed. The experimental results showed that internal energy-dissipating bars exhibited greater energy dissipation. In contrast, the joint with the new external energy dissipater had higher initial stiffness than the joint with internal energy-dissipating bars. In addition, the force transmission mechanism and the calculation formula of the initial rotational stiffness of the joints were deduced through theoretical analysis, and the theoretical derivation was further verified by combining the experimental values. Overall, both joints conformed to the definition of semi-rigid connections in EC3, and the joint design conformed to the "strong column and weak beam, strong joint and weak member" principle. Finally, a new anchoring system for the energy dissipaters is proposed to ensure the effective connection between the energy dissipater and the bearing.