Shaking table test on seismic performance of continuous rigid frame bridge with cast-in-place and fabricated super high piers

Abstract

The seismic performance of a continuous rigid frame bridge with cast-in-place or fabricated super high piers (CRFB-CSP or CRFB-FSP) is still in the exploratory stage. In this study, four 1/20 scaled models of a main CRFB-CSP, CRFB-FSP, and two adjacent bridges (AB) are designed and manufactured. By considering the longitudinal direction as an example, the seismic performance of CRFB-CSP and CRFB-FSP under the action of non-long-period (NLP), non-pulse-like long-period (NPLP), and pulse-like long-period (PLP) ground motions is studied through a shaking table test; in particular, the impact of pounding between the main bridge (MB) and AB is considered. The results show that both CRFB-CSP and CRFB-FSP reflect higher-order mode participation (HMP) characteristics with and without pounding conditions. The influence of HMP on the seismic response of the CRFB-CSP and CRFB-FSP increases as the ground motion intensity increases. The HMP of the CRFB-FSP is more significant than that of the CRFB-CSP. After considering the pounding, the influence of the HMP increases significantly under the PLP ground motion. Moreover, the peak pounding force (Pf) between the MB and AB is higher under PLP and NPLP ground motion excitations. Additionally, Pf is greatest when the velocity pulse period is close to the first-order vibration period of the MB. The Pf value between CRFB-FSP and AB is greater than that between CRFB-CSP and AB. After considering the pounding, the longitudinal peak displacements of the main beams of the CRFB-CSP and CRFB-FSP decrease. Pounding usually increases the horizontal and vertical acceleration responses of the main beam and pier top of the CRFB-CSP and CRFB-FSP, which may have a significant impact on the failure mode of the CRFB-FSP piers.