Seismic behaviour of rocking bridge pier supported by elastomeric pads on pile foundation

Abstract

Life line structures such as elevated flyovers and rail over bridges should remain functional after an earthquake event to avoid possible traffic delays and risk to general public. Generally, restraining the structure by reducing the degrees of freedom often cause serious damages that occurs during a seismic event through yielding of the structural components. By allowing the structure to rock through uplift using suitable arrangements can be a plausible seismic resilient technique. In this context, this article proposes a novel seismic resilient pile supported bridge pier foundation, which uses elastomeric pads installed at top of pile cap. The effect of pile soil interaction along with ground response analysis is also incorporated in the full bridge model adopted for the study. One dimensional equivalent linear site response analyses were performed to arrive at the amplified/attenuated ground motions along the depth of soil.The seismic performance of the proposed bridge with new rocking isolation concept is compared with existing bridge located in medium seismic zone of India. With the help of non-linear dynamic time history analysis and nonlinear static pushover analysis, the bridge modelled using the proposed novel rocking isolation technique shows good re-centering capability during earthquakes with negligible residual drifts and uniform distribution of ductility demand along the piers of the bridge considered in this study.