预应力混凝土结构的声发射实验研究

发布时间：2018-05-25 06:03

本文选题：声发射 + 预应力混凝土　；参考：《长沙理工大学》2015年硕士论文

【摘要】：声发射技术作为当前一种新型的被动无损检测技术,其原理简单,具有实时、动态、方便、直观、连续等优点,广泛的应用于材料的性能和结构损伤的评价中,能够对结构的安全性能和损伤程度进行很好的预警和评判。本文利用声发射技术对预应力混凝土结构实验中的声发射特性进行了探索和研究。主要研究内容和研究成果:(1)在预应力简支T梁尝试进行声发射特性实验研究,对声发射参数随时间分布进行了分析,监测了主梁的开裂时间点,发现了裂纹的出现对声波检测存在一定的影响;应用了线性定位技术,发现其可以很好的对裂纹位置进行定位。(2)在预应力简支箱梁实验应用了声发射技术,对声发射参数随时间分布进行分析,发现其可以很好的描述主梁内的裂纹扩展情况;进行了声发射参数关联分析研究,发现能量随平均频率和事件随幅值的分布随荷载的变化规律,得到了幅值随平均频率的分布规律;应用了平面二维定位技术,通过对比分析发现了该技术对多裂纹可以进行较好的定位。(3)预应力混凝土斜拉桥主梁上利用声发射技术进行了实验监测,通过对声发射参数随时间的分布,发现了主梁的开裂时间点和失稳破坏点,该两个特征可以作为弹性体系支撑工程结构开裂和破坏的预警;通过对比分析能量-平均频率的分布图,发现钢筋屈服后,主梁释放的声波携带大量的低频声波;主梁失稳阶段,主梁释放的声波信号携带大量的中低频声波,主梁破坏的瞬间释放大量的高能和中高频的声波信号;同时使用了线性定位技术和平面二维定位技术,发现二者分别可以对沿梁纵向和局部的裂纹扩展情况进行定位和描述。
[Abstract]:Acoustic emission (AE) technology, as a new passive nondestructive testing technology, has the advantages of simple principle, real-time, dynamic, convenient, intuitive and continuous. It is widely used in the evaluation of material properties and structural damage. It can predict and judge the safety performance and damage degree of the structure. In this paper, acoustic emission characteristics of prestressed concrete structures are studied by acoustic emission technique. The main research contents and research results are as follows: (1) the experimental study on acoustic emission characteristics of prestressed simply supported T beam is carried out. The distribution of acoustic emission parameters with time is analyzed, and the crack time point of the main beam is monitored. It is found that the occurrence of cracks has a certain influence on acoustic wave detection, and the linear positioning technique is used, which can locate the crack position well. (2) the acoustic emission technology is used in the experiment of prestressed simply supported box girder. By analyzing the distribution of acoustic emission parameters with time, it is found that the acoustic emission parameters can well describe the crack propagation in the main beam, and the correlation analysis of acoustic emission parameters is carried out. It is found that the distribution of energy with the average frequency and the distribution of the event with the amplitude varies with the load, and the distribution of the amplitude with the average frequency is obtained. By comparison and analysis, it is found that the technique can be used to locate multi-cracks in the main girder of prestressed concrete cable-stayed bridge. Acoustic emission technique is used to carry out experimental monitoring, and the distribution of acoustic emission parameters with time is analyzed. The cracking time point and the failure point of the main beam are found. These two characteristics can be used as early warning for cracking and failure of the bracing engineering structure of elastic system, and by comparing and analyzing the distribution diagram of energy and average frequency, it is found that after the steel bar yield, The acoustic waves released by the main beam carry a large number of low frequency sound waves, the acoustic signals released by the main beam carry a large number of medium and low frequency sound waves at the stage of the main beam instability, and a large number of high energy and high frequency acoustic signals are released at the moment of the main beam failure. At the same time, the linear positioning technique and the planar two-dimensional positioning technique are used to locate and describe the crack propagation along the longitudinal and local beams, respectively.
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U446

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