Seismic performance of a hybrid precast bridge pier with prestressing tendons and UHPC-ECC enhanced socketed connection

Abstract

This study proposes a hybrid precast bridge pier with prestressing tendons and a socketed connection (PS) to improve the seismic performance of bridge piers under strong earthquakes. The prestressing tendons are intended to provide self-centering capability, while an ECC layer is arranged in the socket region. UHPC is used near the pier base to delay severe damage in the plastic-hinge region. Three 1:5-scale specimens were tested under pseudo-dynamic loading, and a finite element model was developed to investigate key connection parameters. The results show that the proposed hybrid pier delayed visible cracking, reduced residual displacement, and promoted a more controllable damage pattern compared with the cast-in-place pier. The UHPC-protected pier base shifted damage away from the pier-footing interface, while the prestressing tendons improved the recentering tendency. Parametric analyses indicate that increasing the socket embedment depth can reduce the pier-top displacement and mitigate damage in the pier shaft. Changes in the ECC width had a minor effect on the global displacement response. Reducing the ECC compressive strength may transfer damage from the pier-shaft concrete to the ECC layer. When the ECC strength was reduced to 10 MPa, the peak pier-top displacement increased by 61% relative to the 30 MPa case, accompanied by severe compressive crushing of the ECC layer. These results reveal a trade-off between damage redistribution and global deformation demand. Although the practical repairability of the crushed ECC layer still requires further verification, the transfer of damage from the plastic hinge region to the ECC layer indicates that this layer has the potential to serve as a sacrificial damage-control zone, and can provide a preliminary reference for subsequent research on post-earthquake repair.