【作者】 王欢；

【导师】 张丽梅；

【作者基本信息】 河北科技大学 ， 土木工程， 2015， 硕士

【摘要】 近年来,大跨度空间结构迅速发展,其中空间网架具有重量轻、结构合理、造型优美和力学性能好等优点,被广泛用于大跨度公共建筑和民用设施。然而由于这种结构受荷载作用具有随机性,发生损伤或者破坏的潜在危险较大,如果发生工程事故将导致重大生命和财产损失,因此网架结构的健康监测日益受到重视。在结构健康监测中,传感器的布置对于获得结构的准确信息至关重要。由于现场条件和经济成本等方面的限制,不可能在结构上布置太多的传感器,同时传感器采用不同的布设方式对采集信息的准确性以及损伤识别的精度也有很大的影响,并且测试信号不可避免地受到噪声的影响。因此,在噪声的影响下如何在结构上合理的位置布置有限数目的传感器并获取尽可能多的有效信息就成为传感器布置的关键问题。本文针对上述问题,进行了以下几个方面的研究,并得出了相应的结论。1)考虑到网架结构模态可观测性与损伤可识别性的传感器布置结果不一致的特点,找到了一种协调的Fisher信息矩阵和方差法相结合的传感器布置方法。该方法首先由结构运动方程出发,考虑结构响应与振型和损伤灵敏度之间的关系,根据Fisher信息熵原理,建立同时包含模态振型和损伤灵敏度信息的Fisher信息矩阵,并确立了以协调的Fisher信息矩阵2-范数最大化为准则的目标优化算法,确立传感器初始布置方案。然后以协调的Fisher信息矩阵为条件,在结构动力反应灵敏度和方差法的基础上,找到了把方差函数局部最大值作为衡量结构传感器最佳数目的指标,获得结构最终的传感器布置。2)以一个正放四角锥网架结构为研究对象,采用有效独立法(EI法)、方差法(VM法)、和修正的方差法三种方法进行对比分析,得出修正的方差法的有效性和优势。3)研究了噪声对网架结构传感器布置的影响。用matlab软件生成随机白噪声,考虑该噪声影响情况下,分别用EI法、VM法和修正的方差法进行传感器布置研究。最后比较了加噪声前后传感器布置的情况,得出了噪声对网架结构传感器布置的影响程度,并分析了不同方法对噪声的敏感性。更多还原

【Abstract】 In recent years, large span space structures have been developed rapidly in large span public buildings and civil facilities. It has many characteristics, such as light weight,reasonable structure, beautiful shape, good mechanical performance, etc.. However, with using time continue, the structural damages inevitably emerged and seriously these can lead to many accidents. To solve these problems, the structural health monitoring began.Now, the structural health monitoring often adopted dynamics testing, while sensors’ placement is an essential problem to obtain dynamics signals. Considering the restriction of the field condition and economic cost, it is impossible to setting so many sensors on the structure. At the same time, noise inevitably effect testing signals. Therefore, with noise,laying the limited number of sensors and obtaining the effective damage information are the key problems to realize dynamics testing. In this paper, the following aspects of the research were carried out, and the corresponding conclusions were drawn.1) Because of the inconsistencies between the modal observability and damage identification of the grid structure, the results on sensors’ placement are different.Considering the characteristics on sensors’ placement, a coordinated Fisher information matrix and the variance method(namely Modified variance method) are used in this method. In this method, the Fisher information matrix was established bases on the relationship between structural response and vibration mode and damage sensitivity. And the target optimization algorithm is based on the coordination of Fisher information matrix2- norm.Based on the structural dynamic response sensitivity and variance method, the local maximum value of the variance function is used as a measure of the optimal number of structure sensor. So the sensor placement is obtained by using the Fisher information matrix.2) To show the validity and advantage of these methods, three different methods(EI method, Variance method and modified variance method) were contrasted to detect damages on a square pyramid space grid structure.3) The effects of noises on the sensors’ placement were considered. Firstly some random white noise was obtained by Matlab tool. Next, three methods are used to study the sensors’ placement with noise. Comparison the sensors’ placement before and after adding noise, the results show that noise can influence the sensors’ placement and the modified variance method has good noise robustness.更多还原