DEVELOPMENT OF FRAGILITY CURVES FOR A HIGHWAY BRIDGE IN TEHRAN

A decision tool which its use is becoming popular in the assessment of seismic risk and setting retrofit priorities of bridges is seismic fragility curves. Fragility curves are conditional probability statements which give the probability of a bridge reaching or exceeding a particular damage level for an earthquake as a function of ground motion indices, e.g., PGA, PGV for a given intensity level. Research results indicate that individual bridges suffer different levels of damage, depending not only on the magnitude of earthquake and distance from the epicenter, but also on the structural characteristics of the bridge and the soil type on which it is built. The purpose of this paper is to use an analytical method to generate fragility curves for a highway bridge in Tehran. The bridge has three bays, single-column bents and a concrete box deck. The methodology adopted uses 3-D finite element models, nonlinear static (Pushover) and nonlinear timehistory analysis. First a simple 3-D finite element model of the bridge and afterwards considering the existing bridge inventory and assessing typical characteristics and details, a detailed 3-D model has been created. The influence of modeling aspects of the bridge structure on fragility curves has been investigated by considering the two different structural models for the response analysis.

Keywords:

Bridge , Assessment , Fragility Curve , Finite element ,