Abstract:
To study the impact of different restraint methods and the connection structure between concrete piers and caps on the seismic performance and various indicators of bridge pier specimens, three experimental setups were designed: one featuring a prefabricated square steel tube confined concrete pier (SYP-GT4 specimen), another with a square steel tube confined integral cast-in-place concrete pier (SYZ specimen), and a third with a square section integral cast-in-place concrete pier (SFZ specimen). The pseudo-static test was carried out on the pier caps using displacement loading method, and the failure processes and modes of the specimen were closely observed. Various characteristics, including failure modes, load-displacement hysteretic curves, load-displacement skeleton curves, ductility, energy dissipation and other relevant parameters of the piers were analyzed. The results show that all three concrete pier specimens exhibited similar failure modes, characterized by integral failure due to compression and bending. Notably, SYZ specimens outperformed SFZ specimens with a 46.5% increase in horizontal peak load, superior hysteretic energy dissipation capacity, and better ductility, indicating that integral bridge piers constrained by square steel tube demonstrate superior seismic performance compared to cast-in-place concrete piers. Furthermore, when comparing SYP-GT4 specimens to SYZ specimens, they exhibited a similar horizontal peak load value, a 24.1% increase in displacement ductility coefficient, minimal residual displacement, and enhanced deformation recovery capabilities. The hysteresis curve showed a fuller spindle shape without obvious pinching. The connection structure has little effect on the degradation of strength and stiffness, and their seismic performance is similar.
