移动荷载作用下梁结构损伤检测的数值与试验研究

发布时间：2019-02-09 15:16

【摘要】：当结构出现损伤时,对结构的状态进行诊断和评估,以准确识别出结构的损伤位置和损伤程度,进一步分析损伤出现的原因,这一过程的实现就是结构损伤检测。根据结构损伤检测报告,设计人员对结构安全与否进行评价,进而提出对建筑结构进行维护加固的最佳方案,从而最大限度避免结构安全事故的发生。梁结构是工程中常见的一种结构形式,是主体结构的重要组成部分,广泛应用于建筑、市政、桥梁等工程领域。本文以梁为研究对象,采用无厚度的弹簧单元模拟梁结构中出现的微小损伤。探索如何设置弹簧单元的相关参数,才能使数值模型更加贴近工程实际。在损伤梁上施加移动荷载,得到损伤梁的动力特性。采集任意点瞬态响应数据绘制位移时程曲线和加速度时程曲线。对时程曲线数据进行分析和处理,以确定梁结构的损伤位置。基于对损伤检测问题相关文献的学习,本文从以下几个方面展开研究:首先,通过建立梁结构动力学方程以及对损伤梁进行振动分析来研究移动荷载作用下损伤梁的力学性能。基于该理论,在ANSYS软件中建立移动荷载作用下的损伤梁模型,选择弹簧单元模拟厚度可忽略不计的微小损伤,在梁上施加移动荷载,获得不同损伤程度、不同荷载质量、不同移动速度下的位移时程曲线和加速度时程曲线。其次,根据实验室现有条件设计模型试验。在试验用梁模型上设置不同位置和不同程度的裂缝损伤,按照不同荷载质量、不同移动速度、不同测点位置等工况进行对比分析。最后,应用去噪、小波变换等方法进一步处理分析试验和数值模拟所得的数据,得到损伤的位置及各因素对检测结果的影响。在损伤检测中,施加的移动荷载质量越大,速度越小;被检测的损伤程度越大;损伤位置距离测点越近时,检测效果越明显。对于同种工况和同种检测条件下,加速度时程曲线比位移时程曲线的检测效果明显。原本看不出损伤的位移时程曲线,经过小波变换后,在损伤位置处尺度大于某个值时光斑变得较明显,选取其中一个尺度的小波变换图,可以在损伤处发现明显凸起,可以成功检测出损伤。以上有关移动荷载作用下梁结构损伤检测的研究,对后续其他类型结构研究具有一定参考价值。
[Abstract]:When the structure is damaged, the state of the structure is diagnosed and evaluated, in order to accurately identify the damage location and damage degree of the structure, and further analyze the cause of the damage, the realization of this process is structural damage detection. According to the structural damage detection report, the designer evaluates the safety of the structure, and then puts forward the best plan for the maintenance and reinforcement of the building structure, thus avoiding the occurrence of the structural safety accident to the maximum extent. Beam structure is a common structural form in engineering and an important part of the main structure. It is widely used in the construction, municipal, bridge and other engineering fields. In this paper, a thickness-free spring element is used to simulate the small damage in beam structure. In order to make the numerical model more close to the engineering practice, this paper explores how to set the relevant parameters of the spring element. The dynamic characteristics of the damaged beam are obtained by applying moving load on the damaged beam. The transient response data of any point are collected to draw the displacement time history curve and acceleration time history curve. The time history curve data are analyzed and processed to determine the damage location of the beam structure. Based on the study of the related literature on damage detection, this paper studies the following aspects: firstly, the mechanical properties of the damaged beam under moving load are studied by establishing the dynamic equation of the beam structure and analyzing the vibration of the damaged beam. Based on this theory, the damage beam model under moving load is established in ANSYS software, and the spring element is selected to simulate the small damage with negligible thickness, and the moving load is applied to the beam to obtain different damage degree and different load quality. Displacement time history curve and acceleration time history curve under different moving velocity. Secondly, the model test is designed according to the existing conditions in the laboratory. Different positions and different degree of crack damage are set on the beam model of the test, and compared and analyzed according to different load mass, different moving speed, different measuring point position and so on. Finally, the data obtained from the experiment and numerical simulation are processed by denoising and wavelet transform, and the location of the damage and the influence of various factors on the detection results are obtained. In damage detection, the larger the mass of moving load is, the smaller the speed is; the greater the degree of damage is detected; the closer the damage position is to the measuring point, the more obvious the detection effect is. For the same working conditions and the same detection conditions, the acceleration time history curve is more effective than the displacement time history curve. The displacement time history curve of the damage could not be seen originally. After wavelet transform, the spot became more obvious when the scale of the damage was larger than a certain value, and the wavelet transform diagram of one of the scales could find the obvious protruding at the damage place. Damage can be detected successfully. The above research on damage detection of beam structure under moving load has some reference value for other kinds of structures.
【学位授予单位】：山东农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU317

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