基于压电主动传感法的斜拉桥销铰连接锚固区病害监测理论和方法研究

Because of the structural complexity and force concentration, the anchorage zone for cable-girder connection in cable-stayed bridge was regarded as the critical part for early design optimization and monitoring in its service life. On the other hands, piezoceramic materials have been widely used in aerospace/machinery/civil and other areas for structural health monitoring due to it excellent electromechanical characteristic. In this project, the piezoelectric active-sensing technique was introduced to detect the health condition of pin-connected joint-based anchorage zone in cable-stayed bridge in its service life. At first, theoretical derivation based on elastic mechanics and contact mechanics was employed to research the properties for stress wave propagation through the contact surface of two objects, and the influence mechanism for stress wave propagation and attenuation after the physical property changes for the contact surface. Then, feedback response and identification mechanism for the stress wave to the occurrence of two kinds of diseases in the anchorage zone, was theoretical analyzed and numerical simulated, respectively. At last, a two-step health monitoring theory and method, which combines the piezoceramic electro-mechanical impedance method and stress wave-based method, was proposed to detect and monitor the health condition and service status for the pin-connected joint-based anchorage zone, and a laboratorial experiment using a full-scale model was employed to validate the effectiveness of the proposed method. .The project aims at the widely demands of the routine testing and maintenance to the key components of bridges. The final purpose is to realize the long-term online health monitoring for the cable-girder anchorage zone with pin-connected joint, and reduce the costs for routine testing and monitoring. Therefore, a significant social and economic benefit can be found to guarantee the normal working and safety service for the bridges.

斜拉桥索梁连接锚固区结构复杂、受力集中，是前期设计优化和后期检(监)测的关键部位，而压电陶瓷材料因其优良的机电特性而广泛应用在航天、机械、土木等领域的结构健康监测中。本项目尝试将压电主动传感法应用到斜拉桥销铰式索梁连接锚固区的健康监测上来，首先，理论推导应力波在两物体接触面间的传播特性，以及接触面物理属性改变对应力波能量传播和衰减特性的影响机理；之后，理论解析和仿真模拟检测应力波对锚固区两类病害的反馈响应和识别机理；最后，利用销铰连接足尺模型试验，验证所提出的销铰锚固区病害的分步监测理论和方法的有效性，即集合压电阻抗法和压电波动法，一站式实现病害的异常预警、分类判断和程度估计。本项目瞄准桥梁结构关键构件的日常检测和维护的广泛需求，以实现桥梁索梁连接系统的长期实时在线监测为目的，降低日常检测和监测成本，对保障桥梁结构的正常工作和安全运行具有重大的社会效益和经济效益。

斜拉桥索梁连接锚固区结构复杂、受力集中，是前期设计优化和后期检（监）测的关键部位。本项目针对斜拉桥销铰连接锚固区的多种病害形式（索力异常和构件损坏等），提出了一种基于压电波动导波技术的病害监测识别理论方法，借助于接触力学相关知识，公式推导出了销轴-销孔接触面积和外界施加法向力之间的关系，即接触面积与法向力的平方根成正比例关系；随后，通过有限元数值仿真和销铰连接缩尺模型试验验证了所提方法的有效性，在销轴和销座表面分别粘贴压电陶瓷传感器，监测了兰姆波在销铰结构中能量传播衰减程度，间接反映了销轴与结构间接触面积的微变化，集合了压电阻抗法和压电波动法，实现了对销式结构受力状态的准确评估和监测，从而一站式实现了病害的异常预警、分类判断和程度估计。.针对销铰连接结构的销轴-销孔接触面积变化量不宜精准控制，不便于直接开展研究的问题，项目组采用了一个管螺纹连接结构来进行验证，通过改变螺纹管与连接件的连接圈数即可定量地改变二者的接触面积。项目组首先探究了压电阻抗信号对连接结构接触面积改变的响应结果和识别效果，深入研究了在不同松动工况下结构粘贴压电片导纳信号的变化规律，提出了基于压电阻抗技术的管螺纹接头松动病害识别方法和装置。与此同时，探究了压电应力导波在管螺纹接触面先后两次的正逆向路径传播，借助于时间反演技术的时间空间聚焦特性，提出了基于压电时间反演技术的管螺纹接头病害识别方法和装置，通过数值仿真和试验验证了其识别有效性及优良的噪声鲁棒性。最后，研究者还在本课题研究成果基础上，将识别理论加以完善和改进，提出了基于压电阻抗频移技术的管道泄漏和混凝土柱轴压破坏的监测识别装置和识别方法，这也进一步丰富了本课题的研究成果，为其实用化应用打下了坚实的基础。