利用压电陶瓷的钢管混凝土密实性试验研究

发布时间：2018-06-17 05:47

本文选题：钢管混凝土 + 压电智能骨料　；参考：《沈阳建筑大学》2013年硕士论文

【摘要】：近年来,随着建筑高度的不断提高,钢管混凝土结构突显其独特的优势。然而,由于钢管内部隔板的存在,导致混凝土在浇筑完成之后,隔板下部存在局部孔洞等不密实的情况。此外,由于混凝土本身的收缩,使钢管与核心混凝土在界面处脱开或者是核心混凝土出现空洞、不密实等现象。混凝土的密实性是保证钢管混凝土结构可靠性的重要前提,直接影响整个结构的可靠性能。因此,对钢管混凝土密实性进行检测将为结构承载力评估提供参考。本文重点研究利用压电智能骨料及波动法对混凝土密实性的进行识别,并对其密实状态进行评估。主要有以下内容：第一部分,利用压电陶瓷对钢管混凝土柱内部混凝土密实性进行试验研究,以确定不密实的位置和程度。将一组压电陶瓷(如镐钛酸铅,简称PZT)预埋在小体积混凝土中,制成具有驱动和传感双重功能的“智能骨料”,并将其预埋在混凝土柱内的指定位置。将一对“智能骨料”作为测试组,分别作为驱动器和传感器激励和接收信号。通过比较两骨料处接收信号并以欧式距离确定两个信号之间的差别,从而实现钢管混凝土密实性的评估。此外本文以超声法对混凝土密实性进行同步测试,同样能准确反映钢管内核心混凝土的密实性情况,表明本文提出的密实性检测新方法是可行的、有效的。第二部分,通过现代声学时间反转概念将导波传播应用到钢管混凝土结构密实性的识别中。为了有效描述混凝土密实性程度,定义两个损伤指数：TR和SYM。激发“智能骨料”产生监测信号,另一组“智能骨料”接收监测信号,同时对接收信号在时域内反转再次激励,接收重构信号。共制作6组足尺试件,分别进行人工缺陷和实际形成的不密实区域的测试。通过选择合适的窄带波激励信号和有效的信号处理,评估混凝土的密实性。试验结果表明：该方法的可行性,可以用这两个损伤指数很好地表达不密实区域和程度。第三部分,采用大型通用有限元分析软件ANSYS模拟人工缺陷在不同信号激励频率下的响应,为混凝土激励频率的选取提供参考。通过施加激励波形的位移,采用瞬态分析,并改变激励波形的周期,模拟结果与实验测试选取的频率相一致。
[Abstract]:In recent years, with the continuous improvement of building height, concrete filled steel tube (CFST) structure highlights its unique advantages. However, due to the existence of the internal partition of the steel tube, there are local holes in the lower part of the partition plate after the completion of concrete pouring. In addition, due to the shrinkage of the concrete itself, the steel pipe and the core concrete are separated at the interface or the core concrete is hollow and undense. The compactness of concrete is an important prerequisite to ensure the reliability of concrete-filled steel tube (CFST) structure, which directly affects the reliability of the whole structure. Therefore, testing the compactness of concrete-filled steel tube (CFST) will provide a reference for the evaluation of structural bearing capacity. In this paper, piezoelectric intelligent aggregate and wave method are used to identify and evaluate the compactness of concrete. The main contents are as follows: in the first part, the concrete compactness of concrete-filled steel tubular columns is studied by using piezoelectric ceramics to determine the position and degree of uncompaction. A group of piezoelectric ceramics (such as lead pick titanate, PZT) are preburied in small volume concrete to make "intelligent aggregate" with dual functions of driving and sensing, and it is preburied in the designated position of concrete column. A pair of "smart aggregates" are used as test groups, as actuators and sensors to excite and receive signals, respectively. By comparing the received signals between the two aggregates and determining the difference between the two signals with the Euclidean distance, the compactness of concrete-filled steel tubular (CFST) can be evaluated. In addition, the simultaneous testing of the compactness of concrete by ultrasonic method can also accurately reflect the compactness of the core concrete in the steel tube, which shows that the new method proposed in this paper is feasible and effective. In the second part, guided wave propagation is applied to identify the compactness of concrete-filled steel tubular structures through the concept of modern acoustic time reversal. In order to describe the compactness of concrete effectively, two damage indices: TR and Sym are defined. The "intelligent aggregate" is stimulated to generate the monitoring signal, the other group of "intelligent aggregate" receives the monitoring signal, and at the same time, the received signal is reexcited in the time domain to receive the reconstructed signal. Six groups of full-scale specimens were made and the artificial defects and the actual undense areas were tested. The compactness of concrete is evaluated by selecting appropriate narrowband wave excitation signal and effective signal processing. The experimental results show that the proposed method is feasible and can be used to express the undense region and degree. In the third part, the finite element analysis software ANSYS is used to simulate the response of artificial defects under different signal excitation frequencies, which provides a reference for the selection of concrete excitation frequency. By applying the displacement of the excitation waveform, using transient analysis, and changing the period of the excitation waveform, the simulation results are consistent with the frequency selected by the experimental test.
【学位授予单位】：沈阳建筑大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU398.9

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