TIME-DEPENDENT SEISMIC FRAGILITY ANALYSIS OF HIGH PIER BRIDGE BASED ON CHLORIDE ION INDUCED CORROSION

A high-pier and long-span rigid frame bridge is taken as an example, and the nonlinear finite element model of bridges is modeled by using OpenSees program. The deterioration of the diameter and yield capacity induced by chloride corrosion is accounted for longitudinal steel. The sectional nonlinear analyses are applied to investigate the influence of chloride ion induced corrosion (CIIC) on aseismic capacity of high piers. A one-record time history analysis is applied to qualitatively study the influence of CIIC on the aseismic demand of high piers. Moreover, 15 ground motions are selected to conduct multi-records incremental dynamic analyses. The logarithm regression analysis for the ratios of the capacity and demand are adopted to develop the time-dependent fragility curves so as to evaluate the time-variable aseismic performance of the bridge with high piers. It is concluded that: the CIIC reduces the yield bending moment of high piers, whereas the ductility capacity increases slightly; the corrosion of longitudinal steels evidently increases the displacement and curvature demand of high piers; furthermore, the aseismic fragilities of various damage states increase along with the service time of a bridge during its life-cycle design reference period.