Cyclic loading test of self-centering precast segmental concrete high-speed railway bridge columns with UHPC-filled duct connections

Abstract

Precast concrete high-speed railway (HSR) bridge columns are attractive for standardized HSR bridges, but their applications are rare partly due to a research gap in their lateral behavior. Traditional under-reinforced HSR bridge columns have huge lateral stiffness and poor drift capacity, which means that their prefabrication is not a simple separation-assembly process and requires special research. This study aims to develop a novel self-centering precast segmental concrete (SPSC) HSR bridge column, which is designed to have five major improvements including adopting large-diameter deformed bars as energy dissipation (ED) bars, inter-locking multi-hoops, unbonded post-tensioning (PT) tendons, a cast-in-situ ultra-high performance concrete (UHPC) layer at the bottom joint, and UHPC-filled duct connections. A 1/6 scaled cyclic loading test was conducted on three specimens to validate prefabrication feasibility and assess seismic behavior. The research results show that inter-locking multi-hoops can enable the developed bridge columns to have ductile flexural failure and a drift capacity of up to 5 %. The bridge columns have increased lateral stiffness and strength as well as decreased ductility. UHPC-filled duct connections can cause the strain amplification of ED bars at the bottom joint. The bottom joint opening dominates lateral deformation while the influence of joint sliding can be neglected. The bridge columns have good ED capacity and the equivalent hysteretic damping ratio of about 20 % at the drift ratio of 5 %. The bridge columns have the excellent self-centering capacity to control residual drift ratio in an allowable range before flexural failure. The acceptable drift ratios are suggested to be 3.5 % and 4.0 %, respectively, for the SPSC HSR bridge columns without and with PT force.