Shaking Table Response of RC Bridge Piers with Lap-Spliced Longitudinal Steels in Low Seismic Regions

摘要

The near fault ground motion (NFGM) is characterized by a single long period velocity pulse of large magnitude.(Somerville et. al 1997) Extensive research for the far fault ground motion (FFGM) have been carried out in strong seismic region, but limited research have been done for NFGM in low or moderate seismic regions because of very few records. For reinforced concrete (RC) bridge piers constructed before implementing the 1992 seismic design code in Korea, longitudinal reinforcing steels were practically lapspliced in the plastic hinge region between column and footing. This research aims at investiating the seismic behavior of RC bridge piers with lap-spliced longitudinal steels subjected to NFGM in lowor moderate seismic region. Five RC pier specimens with a diameter of 400 mm and height of 1400 mm were teted on a shake table, and two identical specimens were tested under a quasi-static load and a pseudo-dynamic loa. The effects of lap-spliced longitudinal reinforcing steels are investigated. Shaking test results arecompared to those by Quasi-static test and Pseudo-dynamic test. It was concluded that: a) displacemen ductility was significantly decreased in RC column specimens with lap-spliced longitudinal reinforcingsteels; b) bond failure in the lapped starter bars and buckling of the longitudinal steel bars initiated ailure in RC specimens with and without lap-spliced longitudinal steels, respectively; c) more transverse reinforcing steels induced better displacement ductility; and d) a decrease of displacement ductility and energy dissipation was observed in the specimens on a shake table excitation in comparison with the specimens by the quasi-static and the pseudo-dynamic test.