基于车辆静置的桥梁质量归一化振型快速识别方法研究

Bridge mass-normalized mode shape is essential for finite element model updating, response prediction, load estimation, and condition assessment. Fast identifying high accuracy and spatial resolution mode shapes is a crucial task in the field of bridge engineering. A parked vehicle is employed as carrier for additional mass and sensor, and the mass-normalized mode shape is identified fast via measuring the frequency of the parked vehicle-bridge system. Firstly the relationship between the bridge frequencies changes due to a parked vehicle and the amplitudes of the mass normalized mode shapes at the parking point is established through theoretical derivation. Subsequently the algorithm and procedures to extract the mode shapes fast by using the frequencies measured on a two-axle vehicle which parks at different locations of the bridge progressively are proposed. Then the transfer mechanism of test error is analyzed and used to evaluate the identification error of the proposed method. The mode shape identification method makes good use of the bridge essential property of bearing vehicle load, flexible mobility and adding mass function of the vehicle. Mass-normalized mode shapes with high accuracy and spatial resolution are identified fast by frequency measurement. This project aims to obtain substantive breakthrough in mass-normalized mode shape identification and provide basis for bridge inspection and monitoring through theoretical analysis, numerical simulation and experimental study.

桥梁的质量归一化振型在有限元模型修正、响应预测、荷载估计和状态评估中发挥着重要作用。快速识别高精度和高空间分辨率的质量归一化振型是桥梁领域中的重要任务。本项目采用车辆作为附加质量和传感器载体，通过测试静置车辆-桥梁系统频率来快速识别质量归一化振型。首先，通过理论推导揭示静置于桥梁不同位置处车辆-桥梁系统频率和桥梁本身自振频率之间的差值与该点处桥梁本身质量归一化振型幅值的本质物理关系；然后提出通过测试两轴车辆-桥梁系统的频率，快速识别桥梁质量归一化振型的方法；最后分析测试误差的传递机理，评估识别方法的误差。该方法充分利用桥梁承受车辆荷载的基本属性，发挥车辆灵活的移动能力和附加质量功能，化振型识别为频率识别，快速识别高精度和高空间分辨率的质量归一化振型。项目采用理论分析、数值模拟与试验相结合的研究方法，旨在桥梁质量归一化振型识别方法上取得实质性突破，为桥梁工程检测和监测提供基础和依据。

质量归一化振型振型是反映其特性的主要动力指标之一，振型在桥梁监测和检测中发挥着重要作用，高效率、高精度和低成本地识别质量归一化振型是桥梁领域内的重要任务。针对传统方法存在需要大量的传感器、且无法得到质量归一化振型、或受路面不平顺影响较大等问题，本项目提出了一种基于车辆静置的桥梁质量归一化振型识别方法。项目取得的主要成果包括：（1）展示了静置车辆-桥梁系统频率与桥梁本身频率不同，且随着车辆静置位置的变化而变化的现象；揭示了静置车辆-桥梁系统频率和桥梁频率之间的差值与桥梁质量归一化振型幅值的本质物理关系，建立了基于车辆静置的桥梁质量归一化振型识别理论。（2）根据传感器的安装位置和测试车辆的轴距，分别提出了通过测试静置车辆-桥梁系统频率来识别桥梁振型的“短轴距车辆-直接法”、“长轴距车辆-直接法”和“长轴距车辆-间接法”，并明确了各自的适用范围。本项目提出的方法将车辆逐步静置（停靠）于选定位置，形成静置车辆-桥梁系统，测试该系统的频率；然后移动车辆至下一位置，停靠后形成新的静置车辆-桥梁系统并测试其频率；以此类推，“随停随测，即测即走”，通过测试系列静置车辆-桥梁的系统频率，识别桥梁振型，因此称之为基于车辆静置的桥梁振型识别方法。数值算例和试验表明该方法充分利用了桥梁承受车辆荷载的基本属性，发挥车辆灵活的移动能力，解决了传统方法难以质量归一化振型的难题，避免了路面不平顺的影响；且只需少量传感器，化振型识别为频率识别，具有测试简单和精度高的优点。（3）系统研究了车/桥质量比和车辆刚度等因素对振型识别精度的影响，提出了面向典型桥梁的测试车辆参数确定原则。（4）项目在国内外期刊发表论文19篇，其中SCI收录13篇，EI收录5篇，授权发明专利9项。项目成果为桥梁监测和检测提供依据了基础和依据，具有较大的理论意义和工程实用价值。