【作者】 李晶；

【导师】 郑建军； 王秀丽；

【作者基本信息】 兰州理工大学 ， 结构工程， 2011， 硕士

【摘要】 工程结构模态参数的识别是健康监测、故障诊断、振动控制和动态特性分析的重要内容。对于重要的大型建筑的健康监测是一个倍受人们关注的重要课题。当前,我国的大跨度空间结构建设达到一个空前发展的高潮时期,其建筑数量和规模都是历史上前所未有。从空间结构的发展趋势来看,跨度将越来越大。这些结构新颖、技术先进的建筑,给结构的设计、计算和施工都带来了巨大的机遇和挑战。由于突发事故、地震、风载和运营载荷的作用使得大型建筑产生损伤累积并由此引发破坏性事故。事实上,结构的内部损伤必然导致结构动力特性的变化,例如结构的振动频率、阻尼和振型发生变化。振动频率、阻尼和振型的变化能够被用来识别结构内部的损伤。本文的主要工作和结论:(1)对一个网架模型结构进行试验模态分析,首先,对网架模型结构建立了有限元模型,并分析其动力特性,得到网架模型的频率和振型。然后,利用时域的随机子空间识别法对网架模型进行实验模态参数识别,通过传感器和数据采集系统得到结构的实验数据,再对实验数据进行后处理。结果表明理论计算和实测结果吻合较好。(2)对一个网架结构进行损伤识别数值模拟,采样有限元软件建立仿真模型,利用减小单元面积的方法来模拟网架结构的损伤变化,利用将网架的节点位移转变为单元的应变的方法,对网架结构进行损伤识别分析。并分析了应变模态对网架结构进行了不同损伤情况的损伤识别,证实了一阶相对应变对结构损伤识别的有效性。更多还原

【Abstract】 Engineering modal parameter identification is the important content of health monitoring, fault diagnosis, vibration control and dynamic characteristics. For important health monitoring of large buildings is an important issue much attention. At present, China’s construction of large span space structure of the climax to a period of unprecedented growth, the number and scale of its construction are unprecedented in the history. From the development trend of spatial structure, the span will increase. The new structure, advanced technology architecture, to the structural design, calculation and construction have brought great opportunities and challenges. As incidents, earthquakes, wind load and operating load of the role of making large-scale architecture of damage accumulation, and triggered devastating accident. In fact, the structure of the internal damage will inevitably lead to changes in dynamic characteristics, such as the structure of the vibration frequency, damping and mode change. Vibration frequency, damping and mode shapes can be used to identify structural changes in internal damage.The main work and conclusions include:(1) In this paper, the structure of a space truss model of experimental modal analysis, first of all, built on the grid model structure finite element model, and analyze the dynamic characteristics of the model by grid frequency and mode. Then, using the time domain stochastic subspace identification method grid model experimental modal parameter identification, sensors and data acquisition system by the structure of the experimental data obtained, and then post-processing of experimental data. The results show that the theoretical calculations and experimental results agree well.(2) A grid structure damage identification numerical simulation, finite element software to establish the sampling simulation model Reduce the use of unit to simulate the damage area changes, the use of the special nature of grid cells, using the node into a cell strain displacement method, the grid structure of the damage identification. And the strain modal analysis carried out on the network structure of different injuries in the identification, confirmed by first-order relative strain on the effectiveness of structural damage identification.更多还原