Exploring Time-Varying Characteristics in Drive-By Bridge Frequency Extraction with the Second-Order Synchrosqueezing Transform
Exploring Time-Varying Characteristics in Drive-By Bridge Frequency Extraction with the Second-Order Synchrosqueezing Transform
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DOI：
10.1061/jbenf2.beeng-5979
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发表时间：
2023-04
影响因子：
3.6
通讯作者：
Chengjun Tan;Hua Zhao;E. Obrien;N. Uddin;Chul-Woo Kim
中科院分区：
文献类型：
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作者：
Chengjun Tan;Hua Zhao;E. Obrien;N. Uddin;Chul-Woo Kim
近年来，由于成本低，方便，估计桥梁的第一个固有频率的概念，通过间接测量过往车辆得到越来越多的关注，被称为驾驶桥梁结构健康监测。由于车辆作为一个移动质量添加到桥梁，该系统是非平稳的时变特性。大多数相关的研究假设恒定的桥梁和车辆频率的车辆-桥梁相互作用（VBI），这是适当的，只有当VBI的影响可以忽略不计。当车辆质量与桥梁质量（通常是铁路桥梁的一个特征）相比很大时，相互作用效应不能忽略。因此，本文提出了一种非线性时频分析方法来研究频率的时变性质的VBI系统使用二阶同步压缩变换。与经典的线性方法（如小波变换和短时傅立叶变换）相比，该方法可以显著提高时频表示的能量集中度，从而可以清晰地显示频率的变化。此外，一个指标，提出了自动选择的参数与所提出的方法，以获得合适的结果。数值模拟和实验室实验进行了研究所提出的方法的可行性。研究发现，由于VBI的时变特性，车辆和桥梁的频率都是时变的。因此，提取的行车桥梁频率应与使用直接（桥上自由振动）测量发现的频率区分开来。
Recently, due to low cost and convenience, the concept of estimating the bridge’s first natural frequency through indirect measurements of a passing vehicle has gained increasing attention—known as drive-by bridge structural health monitoring. As the vehicle acts as a moving mass added to the bridge, this system is nonstationary with time-varying characteristics. Most related studies assume constant bridge and vehicle frequencies of vehicle–bridge interaction (VBI), which is only appropriate when the VBI effect is negligible. When the vehicle mass is significant compared with the bridge mass, often a feature of railway bridges, the interaction effect cannot be ignored. Therefore, this paper presents a nonlinear time–frequency analysis approach to examine the time-varying nature of frequencies in the VBI system using the second-order synchrosqueezing transform. In comparison to the classical linear approaches, such as wavelet transform and short-time Fourier transform, the proposed method can significantly improve the energy concentration of the time–frequency representations, resulting in a clear pattern to show how the frequencies change. In addition, an indicator is proposed to automatically select the parameters with the proposed approach to obtain suitable results. Both numerical simulation and laboratory experiments are carried out to investigate the feasibility of the proposed approach. It is found that due to the time-varying nature of VBI, the frequencies of both vehicles and bridges are time-varying. Therefore, the extracted drive-by bridge frequency should be distinguished from that found using direct (on-bridge free vibration) measurements.