Risk Assessment of Bridges under Multihazard Effect of Earthquake and Flood-Induced Scour

在洪水引发冲刷的情况下发生地震，对于位于地震多发洪水多发区的桥梁来说，是一种关键的多重危险情景。这项研究的目的是研究这种多危险情景对桥梁设计的影响。将制定一个多风险分析框架，以评估位于美国三个地震活跃、洪水易发地区的代表性桥梁的可靠性，并量化地震和冲刷联合作用下与这些桥梁相关的风险。建立区域洪水灾害曲线，并将这些灾害曲线与区域地震灾害相结合，描述桥梁的多险情。根据开发的洪水风险曲线计算的桥梁冲刷将纳入有限元分析。将进行可靠性分析，以评估由于各种分析模块中涉及的不确定性而导致的桥梁性能的变异性。结果将以(1)脆弱性表面和曲线以及(2)不同多危害情景的风险曲线的形式呈现。多危害分析框架将被用来研究几种抗震加固技术在洪水引起的冲刷情况下用于地震作用下的桥梁的有效性。这项研究完成后，该专业将有机会获得关于桥梁在地震和洪水引起的冲刷的多重危险影响下的性能的全面知识库。研究结果可进一步用于研究区域内桥梁的损失评估和未来事件下公路交通网络的性能评估。这项研究旨在教育研究生和本科生进行多阶段的多危害风险评估。将开发几个在线模块，使教育工作者、国家DOT和执业工程师能够将研究成果用于各自的目的。

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.