Pseudostatic Behavior of Precast Piers with Composite Pier–Pile Cap Connections: Experimental Investigation

A novel composite connection, the steel–concrete composite connection with notched perfobond connectors (NPCs), is proposed for bridge pier–pile cap joint in this paper. In the steel–concrete composite connection with NPCs (SCCN), connection steel plates pre-embedded at the bottom of the pier column are bolted to the pile cap. The load from the pier column to the pile cap is transferred through a steel–steel connection rather than a traditional concrete–concrete connection. To investigate the failure modes and the hysteretic behaviors of precast piers with SCCN, pseudostatic capacity tests of two half-scale specimens have been conducted, with the axial compression ratio (n) of 0.17 and 0.06, respectively. The results show that the precast piers with SCCN present typical flexural failure, the same as cast-in-place (CIP) piers. Concrete cracking, longitudinal rebar yielding, concrete spalling and crushing, and longitudinal rebar fracture are successively observed. Concrete cracking and crushing both appear at the bottom of the pier columns but above the steel jacket. The hysteretic curves of the precast piers have a large shape with a slight pinching. The ductility and equivalent damping coefficient of the specimens are close to CIP piers. Compared to a specimen with n = 0.06, the flexural capacity and initial stiffness of a specimen with n = 0.17 increase by 44% and 37%, respectively. Furthermore, the residual drift ratios of the specimens with n = 0.17 and n = 0.06 are 1/4–1/2 to CIP piers, as 1.28% and 1.00%, respectively. Consequently, the proposed connection can significantly improve elastic deformation and self-centering ability.