Seismic Performance Analysis of Precast Frames Considering Joint Defects

To investigate the influence of partial reinforcement failure in FRP-confined rebar splicing joints on the seismic performance of precast portal frames, based on the experimental results of anchorage performance and splicing performance of the joints, this paper established a macroscopic analysis model of precast concrete portal frames considering partial longitudinal reinforcement failure in the joints using OpenSees finite element analysis software. By combining fiber section modeling technique and strain penetration effect simulation technique, under low-cycle reversed loading condition, the influence of different positions and numbers of failed splicing rebars on the overall seismic performance of portal frames was analyzed. The results show that when the joints have defects, the area of the envelope curve of the structural hysteresis loop will significantly decrease, and it will increase with the increase of the number of failed rebars; the joint defects will slightly reduce the initial stiffness of the overall frame structure, but have a greater impact on the stiffness degradation in the middle and late stages of loading; compared with the defect-free precast frames, the cumulative energy dissipation capacity of the precast frames with edge-failed rebar connections is decreased by 6.40%–24.45%, and their ductility coefficient is decreased by 16.49%–24.45%, while the cumulative energy dissipation capacity of the precast frames with middle-failed rebar connections decreased by 5.26%–11.60%, and their ductility coefficient decreased by 14.11%–20.36%. In summary, for the precast frame structures with defective joints, their hysteresis performance, stiffness degradation, cumulative energy dissipation, ductility coefficient and other evaluation indicators are lower than those of the defect-free precast frames, and the position and number of failed longitudinal rebars in the joints have an impact on the overall seismic performance of the structure.