The occurrence of earthquakes in the presence of flood-induced scour is a critical multi-hazard scenario for bridges located in seismically-active flood-prone regions. The objective of this research is to study the impact of this multi-hazard scenario on the design of bridges. An analytical multi-hazard framework will be formulated to assess the reliability of representative bridges located in three seismically-active, flood-prone regions of US and to quantify risk associated with these bridges under the combined effect of earthquake and scour. Regional flood hazard curves will be developed and multi-hazard scenario for bridges will be characterized by combining these hazard curves with regional seismic hazards. Bridge scour calculated from developed flood hazard curves will be incorporated in finite element analyses. Reliability analysis will be performed to assess the variability of bridge performance due to uncertainties involved in various analysis modules. Results will be presented in forms of (i) fragility surfaces and curves and (ii) risk curves for different multi-hazard scenarios. The multi-hazard analysis framework will be used to investigate the effectiveness of several seismic retrofit techniques for bridges under earthquakes in the presence of flood-induced scour. On completion of this research, the profession will have access to a comprehensive knowledge-base on bridge performance under multi-hazard effect of seismic and flood-induced scour. Results can be utilized further for loss estimation of bridges located in the study regions and for performance evaluation of highway transportation networks under future events. This research is designed to educate graduate and undergraduate students on multiple phases of multi-hazard risk assessment. Several online modules will be developed which will enable educators, state DOTs and practicing engineers to utilize the research outcome for their respective purposes.
