【作者】 刘嫦娟；

【导师】 孙宗光；

【作者基本信息】 大连海事大学 ， 道路与铁道工程， 2007， 硕士

【摘要】 在诸如悬索桥这样的复杂结构的健康监测与诊断中，传感器的布设方案和损伤指标体系的选择直接影响着损伤识别的效果。国内外学者在相关领域进行了大量研究并取得了一定成果，但是由于结构的健康诊断与损伤识别问题的复杂性，目前的研究成果仅仅是初步的，仍存在大量的理论与实际问题有待深入研究。 与大量的结构自由度相比，监测和测量系统的传感器数量是十分有限的，因此对大型复杂结构响应的测量一般都是不完备的，这将导致结构识别结果的不唯一性；加之结构工况的复杂性和工作环境的随机性，合理地布设传感器和恰当地选用健康状态指标对于悬索桥结构的健康诊断是十分重要的。 传感器布设与健康状态指标的选择是密切相关的。目前，根据所用数据的类型将损伤指标大致分为两大类：基于静态特性的损伤指标和基于动态特性的损伤指标。悬索桥是一个由多种材料、不同构件组成的复杂体系，不同部位的损伤对各个指标的影响也是不同的，单一的指标很难识别出悬索桥所有部位的损伤，为此，本文通过ANSYS建立起的有限元模型进行数值模拟，着重分析了在无噪声情况下频率改变比、模态曲率差、静态应变差指标对吊索、主梁、和主缆三种常见损伤类型的识别效果，提出了将频率改变比、模态曲率差、静态应变差指标组成的指标体系来识别悬索桥的损伤。 根据上述三个指标自身的特点提出了一组针对悬索桥的简单易行的传感器布设方法，详细论述了悬索桥检测时应变、频率、模态曲率的测点布置情况。应变测点根据应变分布图来进行布置，频率则是依据动能最大原理来布设，模态曲率测量则是采用逐步累加法利用MAC矩阵来评价测点形成的振型的正交性。 在悬索桥整桥试验模型上对悬索桥可能的损伤情况进行了试验模拟，提取结构损伤前后的频率改变比为输入数据，应用神经网络技术对损伤区域定位进行了试验研究。结果表明除主缆损伤不能定位外，吊索损伤和主梁损伤具有较好的定位效果。频率改变比对模型悬索桥结构定位的可行性为实际工程的损伤检测提供了很大的帮助。更多还原

【Abstract】 The placement of sensors and the selection of index system can greatly affect the identifying results in the health monitoring and diagnosis of complex structures such as suspension bridges .In the resent years the scholars have done a great deal of reserch and got a series of achievement in the two fields, but because of the complication of health diagnosis and damage detection,the acheivement is just primary and there are also many theoretical and practical problems to be studied.Compared with the dofs of the structures, the number of sensors in monitoring and diagnosis system is finite, thus the measurement of structures’ response is also incomplete, therefore it’s impossible to find a decided and doubtless answer for the detection; considering the complicacy of damage cases and the uncertainty of working environment, it’s important to adopt reasonable sensors’ configuration and select fit healthy state indices in suspensions’ health diagnosis.The configuration of sensors and the selection of indices is quite correlated in the damages detection. At the present the indices are generally grouped into two types by the data source: the indices based on the static data and the indices based on the dynamic data. The suspension bridge is a complex system constituting multi-materials and different components, the damages in different positions have different effect on the indices. It’s difficult to identify all types of damages using single index. This paper presents a comparative study of the applicability of frequency changes ratio index, modal curvature difference index and static strain difference index for the three common damage types in the suspension bridges(girder damage hanger damage and cable damage) in the absence of noise based on finite element model modeled by ANSYS software. From the simulation results a practical damage detection methodology of suspension bridges is proposed in this paper by combination usage of those three indices.更多还原