基于导波法的钢管混凝土构件缺陷检测影响因素研究

发布时间：2018-04-30 08:57

本文选题：钢管混凝土 + 缺陷　；参考：《哈尔滨工业大学》2016年硕士论文

【摘要】：钢管混凝土结构因其合理地利用钢管和混凝土的材料特性,受力性能大幅提升而备受关注,又因其施工快速简便而得到广泛运用。然而,当施工不善时,构件中容易出现裂缝、脱空等缺陷,这将影响到钢管混凝土构件及结构的整体受力性能。因此,如何快速地发现钢管混凝土构件的缺陷并判断缺陷的位置和大小是缺陷检测的关键。目前的检测方法有人工敲击法、光纤监测系统法等,但往往检测繁琐且易漏测,而基于导波法的缺陷检测由于耗费低、效率高、检测全面、操作简便且适用范围广而受到关注。为此,本文通过分析导波在钢管混凝土构件中的传播特性,对钢管混凝土构件的缺陷检测影响因素及存在缺陷时的导波响应进行研究。基于此,本文开展以下研究工作:进行钢管混凝土构件导波传递波动方程推导及比对,根据动力学理论,获得了导波检测中钢管混凝土构件的等效面积、等效刚度、等效密度和等效阻尼系数为后续构件整体分析进行简化。并在弹性范围内推导了钢管混凝土构件的动态响应方程,明确底端边界条件对回波信号的影响,分别有刚度E、密度?、构件截面面积A和构件长度L等影响因素,为后续因素分析提供了条件。并将理论解与有限元模拟结果进行比较,证实建模方法的合理性,为后续数值模拟分析提供了理论基础。对钢管混凝土构件初始条件对导波传播的影响进行研究,基于ABAQUS有限元软件和MATLAB编程软件,通过对钢管混凝土构件的频散理论和波的传播效果进行了分析,确定了基于频散方程、传播速度以及构件尺寸的激励首波类型确定方法;并基于ABAQUS有限元软件进行钢管混凝土构件的导波检测数值模拟,分析导波信号激励区域和信号提取区域改变所引起的变化,确定了导波信号激励区域和信号提取区域的合理范围;同时,研究构件材料本身的刚度、泊松比及密度的变化对导波传播的影响,简化其与波速、幅值的关系。进行介质多相性及缺陷回波信号幅值分析,基于蒙特卡洛原理建立二维随机骨料细观模型,并建立了三维多层骨料模型,研究了钢管混凝土介质多相性对导波传播的影响;在钢管混凝土构件中建立轴向缺陷进行缺陷回波信号幅值变化分析,获得了轴向缺陷大小与缺陷回波幅值的关系分析轴向缺陷大小与缺陷回波的关系。研究发现,随着缺陷长度的增大,缺陷幅值先增大后减小,具体缺陷尺寸可由波形分解进一步明确;通过钢管混凝土构件中改变脱离缺陷位置,分析了缺陷位置与缺陷回波的关系,可知当缺陷位于构件末端时缺陷回波信号与构件底端回波几乎重合,检测效果不佳,当缺陷避开首波及末端回波位置时缺陷回波信号清晰易发现。
[Abstract]:Concrete-filled steel tubular (CFST) structure has attracted much attention because of its reasonable use of the material characteristics of steel tube and concrete, and its mechanical properties have been greatly improved, and it has been widely used because of its rapid and simple construction. However, when the construction is not good, cracks and voids will occur easily in the members, which will affect the overall mechanical performance of concrete-filled steel tubular members and structures. Therefore, how to quickly find the defects of concrete filled steel tube (CFST) members and determine the position and size of the defects is the key to defect detection. The current detection methods include manual tapping method, optical fiber monitoring system method and so on, but they are often tedious and easy to leak. However, the defect detection based on guided wave method is concerned because of its low cost, high efficiency, comprehensive detection, simple operation and wide range of application. Therefore, by analyzing the propagation characteristics of guided wave in concrete-filled steel tube (CFST) members, the influence factors of defect detection and the response of guided wave in CFST members are studied in this paper. Based on this, the following research work is carried out in this paper: the wave equation of guided wave transfer of concrete filled steel tube members is deduced and compared. According to the dynamic theory, the equivalent area and stiffness of concrete filled steel tube members in guided wave detection are obtained. The equivalent density and the equivalent damping coefficient are simplified for the whole analysis of the subsequent members. The dynamic response equation of concrete-filled steel tubular member is deduced in elastic range, and the influence of bottom boundary condition on echo signal is determined, including stiffness E, density, section area A and length L, etc. It provides conditions for subsequent factor analysis. The theoretical solution is compared with the finite element simulation result, and the rationality of the modeling method is verified, which provides a theoretical basis for the subsequent numerical simulation analysis. The influence of initial conditions of CFST members on the propagation of guided waves is studied. Based on ABAQUS finite element software and MATLAB programming software, the dispersion theory of CFST members and the effect of wave propagation are analyzed. The method of determining the first wave type of excitation based on dispersion equation, propagation velocity and component size is determined, and the numerical simulation of guided wave detection of concrete-filled steel tube members is carried out based on ABAQUS finite element software. The changes caused by the change of the guided wave signal excitation region and the signal extraction region are analyzed, and the reasonable range of the guided wave signal excitation region and the signal extraction area is determined. At the same time, the stiffness of the component material itself is studied. The influence of Poisson's ratio and density on the propagation of guided wave is simplified, and the relationship between Poisson's ratio and wave velocity and amplitude is simplified. Based on Monte Carlo principle, the two-dimensional random aggregate mesoscopic model is established, and the three-dimensional multi-layer aggregate model is established. The influence of the multiphase property of concrete-filled steel tube medium on the propagation of guided wave is studied. The relationship between the size of the axial defect and the amplitude of the echo of the defect is obtained. The relationship between the size of the axial defect and the echo of the defect is obtained. It is found that with the increase of defect length, the defect amplitude increases first and then decreases, and the specific defect size can be further determined by waveform decomposition. The relationship between defect position and defect echo is analyzed. When the defect is located at the end of the component, the echo signal of the defect almost overlaps with the echo at the bottom of the component, and the detection effect is not good. When the defect avoids the position of the echo at the head and the end, the echo signal of the defect is clear and easy to be found.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TU398.9

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