Rapid rehabilitation of damaged UHPC-NSC composite pier after earthquake

Abstract

Resilience-oriented earthquake engineering requires that engineering structures can recover rapidly after earthquakes. However, the rehabilitation time of bridge piers is strongly dependent on the structure and retrofit plan. Although an ‘ultra-high-performance concrete (UHPC) – normal strength concrete (NSC)’ composite pier, with a cross-section of an outer UHPC tube and inner NSC core, can deliver satisfactory damage control, its post-earthquake rehabilitation has not been reported. This study investigated the rehabilitation performance of damaged UHPC-NSC composite piers. Six damaged composite piers were retrofitted, and cyclic tests were conducted to compare the performance of the retrofitted and original specimens. The actual compressive strength of the re-poured UHPC significantly affected the performance of the retrofitted composite piers. Parametric analysis was conducted based on the validated numerical model to investigate the impact of the rehabilitation time on the retrofitted performance quantitatively. The functions of the critical rehabilitation time were derived with respect to the strength and thickness of the re-poured UHPC, considering the full recovery of the initial stiffness and peak strength as the criteria.