Probabilistic Seismic Performance Assessment of a Bridge-Foundation-Soil System

Abstract

This paper presents the probabilistic seismic performance assessment of an actual bridge-foundation-soil system, the Fitzgerald Avenue twin bridges. A two-dimensional plane strain finite element model of the longitudinal direction of the bridge-foundation-soil system is modelled using advanced soil and structural constitutive models. Ground motions are selected based on the seismic hazard deaggregation at the site, which is dominated by both fault and distributed seismicity. Based on rigorous examination of several deterministic analyses, engineering demand parameters (EDP’s) are determined which capture the global and local demand and damage to the bridge and foundation, and multiple ground motions at various intensity levels are used to conduct seismic response analyses of the system. It was found that the non-horizontal layering of the sedimentary soils has a pronounced effect on the seismic demand distribution to the bridge components, of which the north abutment piles and central pier are critical in the systems seismic performance.