以移动车辆为基底的桥梁动态量测之理论与实践

Frequencies and mode shapes are important dynamic properties for bridges, which are required in various applications. Traditionally, the frequencies and mode shapes of a bridge are measured by the “direct approach”, in that sensors mounted on the bridge are used to record the bridge response for extracting the frequencies and mode shapes. Such an approach can also be regarded as a “fixed sensor system,” which is relatively costly. In 2004, the author first proposed the method for measuring the bridge frequencies indirectly from the response recorded of an instrumented vehicle moving over the bridge. Such an approach is referred to as the “indirect approach” and the test vehicle as a “moving sensor system.” Since no sensors are required to be mounted on the bridge, the indirect approach has the advantages of mobility, efficiency and economy, but it suffers from the disturbance of road surface roughness and other external sources. This project is to develop a leading-edge indirect measurement technique for bridges, which contains two major components: (1) In the software or theoretical part, focus is placed on the development of effective signal processing techniques, use of workable filtering techniques to remove the pollution by road surface roughness and external noises, and implementation of proper transformation techniques to establish bridge mode shapes. (2) In the hardware or experimental part, focus is placed on the fine-tuning of the dynamic properties of the test vehicle, improvement of the wheels’ contact surface with the ground, and verification of the overall technique via model tests and road tests, etc. After completion of this project, a fine-tuned indirect measurement system will be made available for use in the country to provide a high-performance tool for bridge maintenance. In addition, through publication of a number of high-quality papers, the leading role in the area of concern in the world will be strengthened.

桥梁的频率和振型为重要动态参数，用途极广 。传统量测桥梁频率和振型多采《直接量测法》，係利用安置于桥梁之传感器直接从桥梁响应得之，此法属于《固定感应系统》，成本较高。申请人于2004年首先提出《间接量测法》的概念，即是让一装有传感器的试验车通过桥梁，再从车辆所纪录的响应间接攫取桥梁的频率，此处所用的量测车可称为《移动感应系统》。其优点为不须在桥上安装任何设备，具备机动、时效和经济性，缺点则是易受桥面粗糙度及外在干扰。 本研究旨在开发一前沿的桥梁间接量测技术，核心技术有二：在《软件或理论》部分，将建立有效的讯号处理技术； 以滤波技巧过滤粗糙度及外在干扰；并以适当转换技巧获取桥梁振型。在《硬件或实验》部分，则将精进量测车动态特性；改善轮胎接地性能；并进行模型及路面实验。预计本项目完成后，可建立一套高效能的间接量测系统，作为桥梁维护之工具，而通过系列高质量论文之发表，可强化此一领域之国际领先性。

桥梁作为生产生活中跨越沟壑、阻隔的重要节点，在促进人员交流、保障物资运输、推动经济发展等方面有着不可替代的作用。为保障生产生活有序进行，桥梁的安全至关重要。本研究基于一辆移动车辆来识别桥梁动态信息，以降低桥梁健康检测成本、扩大桥梁检测范围、实现快速检测。研究工作致力于推动桥梁健康检测事业的发展，有着重要的现实意义。基于过往的理论研究，自主研发了一辆力学性能稳定的单轴量测车，并通过实桥实验分别在静止状态和运动状态下识别到桥梁的频率。基于过往的理论研究，自主研发了一辆力学性能稳定的单轴量测车，并通过实桥实验分别在静止状态和运动状态下识别到桥梁的频率。车辆扫描法应用过程中，车体自身的响应对识别结果有很大的影响，使得桥梁信息无法准确识别，给车辆扫描法的应用带来了困扰。为了提高车辆扫描法提取的信号的纯净度，提出了利用接触点响应来清除车体自身振动的干扰。结果发现，本方法能够有效滤除车体频率，提高高阶桥梁频率提取效果。对于单自由度和双自由度测量车分别给出了接触点的计算方法，并研究了车体与桥梁之间的振动传递规律。另外，为了提高桥梁动态信息识别效果，提出了利用变分模态分解与带通滤波相结合（VMD-BPF）的技术来过滤杂讯分解桥梁模态信息，BPF用于滤除掉高频不需要的干扰，如粗糙度，VMD用于模态分解。结果表明，VMD-BPF数据处理方法有良好的稳定性，能够很干净地将桥梁模态分解开。针对桥梁振型，本研究结合变分模态分解以及Hilbert变换，并利用接触点响应来对桥梁振型的构造进行了理论研究和有限元模拟。结果发现，利用接触点响应来构造桥梁振型的效果比直接利用车体响应构造出的振型更加完善。除了以上内容外，本研究还做了扩展工作。主要包括：单对称I型截面简支梁侧向和扭转作用的共振和共消现象研究，双自由度测量车之于桥梁动态信息提取的理论研究，利用双轴车对桥梁阻尼的提取，以及基于接触点响应驱车频率成分的桥梁损伤研究。