Effects of CFRP-Repaired Round-End RC Hollow Piers on Postearthquake Recovery of High-Speed Railway Track–Bridge Systems

Abstract Round-end RC hollow piers are commonly used in high-speed railway bridges. However, their earthquake-damaged performance and repair using carbon fiber–reinforced polymer (CFRP) have not been systematically studied. Furthermore, the effect of CFRP repair on the high-speed railway track–bridge system (HSRTBS) is still unclear. This study conducted quasi-static tests on four scaled piers with CFRP repair. An elaborate numerical model of round-end RC hollow piers was developed and validated by tests. This modeling method for repaired piers was then incorporated into the HSRTBS model. Parametric analysis was performed to investigate the effect of repaired piers on the HSRTBS. The results showed that (1) CFRP repair significantly recovered the horizontal bearing and energy dissipation capacity, but its stiffness recovery is limited, with an average restoration of only 47.0%. (2) The numerical model could accurately capture the seismic behavior of the piers before and after CFRP repair, with errors within 19.9%. (3) CFRP repair effectively reduces the transverse displacement and residual deformation of the HSRTBS. (4) A 6-m-high CFRP repair in the prototype HSRTBS model can restore the seismic performance of the damaged pier comparable to that of the intact pier, while it cannot benefit more from further increases in repairing height. This study provides insights for evaluating seismic performance and repair design of earthquake-damaged round-end RC hollow piers repaired with CFRP in high-speed railway bridges.