Framework for determining the dominant hazard of bridges under flood and seismic hazards

The impacts of destructive historical earthquakes and recent disastrous flooding events are major concerns for bridges worldwide. The adverse impacts of future hazards can be mitigated by identifying the most serious hazard and developing relevant disaster prevention measures. In this study, a framework is developed to determine the dominant hazard threatening the safety of bridges subjected to floods and seismic activity. Based on significant hydrologic events, the vulnerability of bridges in the proposed procedure is estimated considering multiple failure modes. The proposed methodology integrates the hazard models and fragility of bridges for comparative reliability assessments. By considering local hazard characteristics, the dominant hazard can be determined for individual bridge sites. This procedure not only suggests an optimal disaster mitigation strategy for each bridge site but also evaluates the effects of the improved seismic performance on the reliability of bridges under flooding hazard, as demonstrated in an illustrative example.