Residual Seismic Performance of Reinforced Concrete Bridge Piers After Moderate Earthquakes

Abstract

Although Korea has long been considered to be free of earthquake hazards, the number of low and moderate earthquakes has increased each year. This study investigates the residual seismic performance of earthquake-damaged reinforced concrete bridge piers that were constructed before or after the implementation of a seismic design code for Korea. Eight circular concrete columns 600 mm (23.6 in.) in diameter and 1500 mm (59.0 in.) in height were constructed with three test parameters: confinement ratio, lap-splice of longitudinal steel, and retrofitting fiber-reinforced polymer (FRP) materials. Reinforced concrete (RC) bridge piers were subjected to artificial earthquake motions using a pseudo-dynamic test (PDT), and then their seismic performance was examined in a quasi-static test (QST). The seismic enhancement of FRP wraps was also investigated. Six specimens were loaded to induce damage by a series of four artificial earthquakes representative of earthquakes in the Korean peninsula. Following the PDT, the six predamaged specimens were subjected to inelastic cyclic loading while under a constant axial load of 10% of the column axial capacity. Two reference specimens without predamage were subjected to similar quasi-static loads. Test results showed that all specimens behaved almost linearly under moderate artificial earthquakes. Except for the ordinary specimens with lap-spliced longitudinal bars, most specimens predamaged during the PDT generally demonstrated good residual seismic performance. The findings also showed that retrofitting RC bridge specimens with fiber composite wraps in the potential plastic hinge region enhanced flexural ductility even for a flexural shear failure mode.