Seismic Fragility Methodology for Highway Bridges

摘要

Bridge fragility curves, which express the probability of a bridge reaching a certain damage state for a given ground motion parameter, play an important role in the overall seismic risk assessment of a transportation network. For various reasons, analytical methodologies for developing these fragility curves have experienced an increase in demand and popularity. However, these methodologies have yet to adequately account for all major contributing bridge components in the generation of analytical bridge fragility curves. There have been some studies which have shown that for certain bridge types, neglecting to account for all of these components can lead to a misrepresentation of the bridges’ overall fragilities. In this study, an expanded methodology for the generation of analytical fragility curves for highway bridges is presented. This methodology considers the contribution of the major components of the bridge, such as the columns, bearings and abutments, to its overall system fragility. In particular, this methodology utilizes some probability tools to directly estimate the bridge system fragility from the individual component fragilities. It is illustrated using a bridge whose construction and configuration are typical to the Central and Southeastern part of the United States and the results are presented and discussed herein. As these analytical methodologies are improved, the fragility information they generate will be more reliable and more likely to be implemented into transportation network loss estimation models and retrofit prioritization strategies.