Scour is a significant issue for bridges worldwide that influences the global stiffness of bridge structures and hence alters the dynamic behaviour of these systems. For the first time, this article presents a new approach to detect bridge scour at shallow pad foundations, using a decentralized modal analysis approach through re-deployable accelerometers to extract modal information. A numerical model of a bridge with four simply supported spans on piers is created to test the approach. Scour is modelled as a reduction in foundation stiffness under a given pier. A passing half-car vehicle model is simulated to excite the bridge in phases of measurement to obtain segments of the mode shape using output-only modal analysis. Two points of the bridge are used to obtain modal amplitudes in each phase, which are combined to estimate the global mode shape. A damage indicator is postulated based on fitting curves to the mode shapes, using maximum likelihood, which can locate scour damage. The root mean square difference between the healthy and scoured mode shape curves exhibits an almost linear increase with increasing foundation stiffness loss under scour. Experimental tests have been carried out on a scaled model bridge to validate the approach presented in this article.

对于全世界的桥梁来说，冲刷是一个重要的问题，它会影响桥梁结构的整体刚度，从而改变这些系统的动力特性。首次，本文提出了一种新方法来检测浅层垫层基础上的桥梁冲刷，该方法使用分散的模态分析方法，通过可重新部署的加速度计来提取模态信息。创建了在墩上有四个简单支撑跨度的桥梁数值模型来测试该方法。冲刷被建模为给定桥墩下基础刚度的降低。使用仅输出的模态分析，对通过的半车模型进行仿真，以在测量阶段激发桥梁，从而获得模式形状的分段。电桥的两个点用于获得每个相位的模态振幅，结合起来以估计整体模式形状。根据对模式形状的拟合曲线，使用最大似然来假定损坏指示器，可以找到冲刷损坏。健康和冲刷模式形状曲线之间的均方根差随着冲刷下基础刚度损失的增加呈现出几乎线性的增加。已经在比例模型桥上进行了实验测试，以验证本文介绍的方法。