Flood may cause the removal of bed material or local scour before seismic activity for bridges located at seismically active as well as flood-prone sites. That, in turn, causes loss of lateral support at the foundation level and this phenomenon effectively reduces the lateral stiffness of the bridge system. These events may take bridge structure to a relatively higher vulnerability state during sequential MainShock–AfterShock action. The present study aims to assess the vulnerability of reinforced concrete bridges (2-span and 3-span) under a multi-hazard scenario of flood-induced scour and sequential seismic events. For this investigation, an appropriate bridge site flood hazard curve derived-local scour depths and ground motion records that come under different hazard levels are adopted. Two-dimensional nonlinear bridge models are developed in suitable finite element platform incorporating soil-pile interaction of bridge sub-structure using recommended nonlinear P-Y springs. To simulate local scour conditions, P-Y springs have been removed up to scour-affected depth to depict the loss of all-around lateral support. Nonlinear time-history analyses are carried out for MainShock alone case and MainShock–AfterShock sequential occurrence for no scour condition as well as for various scour cases. The probabilistic seismic demand model regression fits are established, and associated fragility curves are developed corresponding to different damage states.

洪水可能会导致位于地震活跃区和洪水易发地点的桥梁在地震活动之前清除床层材料或局部冲刷。这反过来又会导致基础水平的横向支撑损失，这种现象有效地降低了桥梁系统的横向刚度。在顺序 MainShock-AfterShock 行动期间，这些事件可能会将桥梁结构带到相对较高的脆弱性状态。本研究旨在评估钢筋混凝土桥梁（2 跨和 3 跨）在洪水引起的冲刷和连续地震事件的多灾害情景下的脆弱性。在本次调查中，采用了适当的桥梁现场洪水危险曲线——当地冲刷深度和不同危险等级下的地震动记录。PY弹簧。为了模拟当地的冲刷条件，PY弹簧已被移除至受冲刷影响的深度，以描绘全方位横向支撑的损失。对 MainShock 单独情况和 MainShock-AfterShock 连续发生无冲刷条件以及各种冲刷情况进行非线性时程分析。建立了概率地震需求模型回归拟合，并根据不同的损伤状态绘制了相关的脆性曲线。