Seismic Performance of Prefabricated Segmental CFST Stiff Skeleton Bridge Pier: Experimental Investigation and Analysis Model

Abstract

Prefabricated bridge piers provide benefits, including improved efficiency, high-quality construction, and minimized environmental impact. For bridges in mountainous areas in high seismic risk regions, large pier heights and high reinforcement ratios in the pier sections limit the applicability of prefabricated piers. To promote the use of prefabricated bridges in these areas, a novel prefabricated segmental concrete-filled steel tube (CFST) stiff skeleton bridge pier was developed in this paper. The stiff skeleton was embedded in the pier segments. The segments were connected by steel bars and were joined to the bent cap and foundation through grouted steel tubes and socket connections, respectively. The seismic performance of the pier was evaluated through quasistatic tests. A hysteretic analysis model (HAM) was developed by incorporating the force and deformation behaviors of the socket segment, followed by a parametric analysis of the pier’s seismic performance. Finally, a method for determining the critical socket depth and a corresponding seismic design framework were established. The results showed that the connections between the pier-bent cap/foundation and pier segments were reliable. The damage to the pier was concentrated at the pier bottom, with the failure mode being the buckling of the steel tube and web at the pier base. The pier exhibited excellent lateral load capacity, energy dissipation, and ductility. The HAM of the pier effectively characterized its hysteretic behavior. The error in lateral load capacity was less than 2%, and the error in deformation was less than 8%. The growth of axial load, steel strength, and concrete strength significantly enhanced the lateral load capacity of the pier, while the increases in the diameter and strength grade of the connecting steel bars improved its initial stiffness. The established framework provided guidance for the seismic design of piers.