Bridge damping ratios are extracted via the skillful use of the single-degree-of-freedom (DOF) test vehicle for the first time in this paper. Central to the simultaneous retrieval of the first few frequencies and damping ratios from the contact (point) response of the bridge is the use of the variational mode decomposition (VMD) and random-decrement technique (RDT). Closed-form solutions are newly derived for the vehicle and contact responses of the damped bridge and validated later numerically. Using the proposed method, one calculates first the mono-component from the contact response by the VMD; then extracts the free-decay response for each mode by the RDT; and finally identifies the frequency and damping ratio by the Hilbert transform. The parametric study confirms that: (1) the contact response outperforms vehicle’s response in retrieving bridge frequencies and damping ratios; (2) the first few frequencies can be identified with robustness for reasonable levels of road roughness, vehicle speed, bridge damping and noise; (1) good result is obtained for the first damping ratio, in spite of the traditional uncertainty existing with damping; and (2) ongoing traffic can enhance the proposed method for bridge identification.

中文翻译：

---

使用单自由度测试车同时检索桥梁的前几个频率和阻尼比

本文首次通过熟练使用单自由度（DOF）试验车提取桥梁阻尼比。从桥的接触（点）响应中同时检索前几个频率和阻尼比的核心是使用变分模态分解（VMD）和随机递减技术（RDT）。封闭形式的解决方案是新推导出的车辆和阻尼桥的接触响应，并在以后进行数值验证。使用所提出的方法，首先通过 VMD 从接触响应中计算单分量；然后通过 RDT 提取每个模式的自由衰减响应；最后通过希尔伯特变换识别频率和阻尼比。参数研究证实：(1) 在检索桥梁频率和阻尼比方面，接触响应优于车辆响应；(2) 对于道路粗糙度、车速、桥梁阻尼和噪声的合理水平，可以稳健地识别前几个频率；(1)尽管阻尼存在传统的不确定性，但第一阻尼比取得了良好的效果；(2) 持续的交通可以增强所提出的桥梁识别方法。