Experimental investigation of seismic behavior of UHPC connection between precast columns and footings in bridges

The lack of seismic capacity of piers leads to bridge collapse in recent earthquakes, such as the 1994 Northridge (USA), 1995 Kobe (Japan) and 2008 Wenchuan (China) earthquakes. For precast bridge piers, the performance of pier connection determines the seismic capacity of the whole bridge. Therefore, a new connection between precast bridge column and footing using ultra-high performance concrete (UHPC) is developed in this paper. The precast column and footing are connected by longitudinal rebars of the column and the footing anchored into the UHPC-filled cage. The connection allows force to be transferred from the column rebars to UHPC, then to the footing rebars by bond effects. To investigate the seismic behavior of precast bridge piers with this new UHPC connection, cyclic tests with two large-scale (1:2.5) models are carried out. One is the precast reinforced concrete (RC) specimen using the proposed new connection, and the other is the cast-in-place (CIP) RC reference. The results show that the failure modes of the specimens are similar, both denoted by crushing of the core concrete above the connection segment. No obvious damage is observed in the connection region, which demonstrates that the precast bridge pier with the proposed connection is emulative of the CIP pier. Furthermore, a finite element model is developed to simulate the cyclic response of the precast column with proposed connection. The deviation between the calculated and measured force-displacement relationships is about 5%, which indicates that the numerical model used herein can be effective to capture the performance of the precast pier with new UHPC connection.