钢筋锈蚀对钢筋混凝土结构动力特性影响的试验研究

发布时间：2018-06-15 01:40

本文选题：钢筋锈蚀 + 阻尼比　；参考：《山东大学》2017年硕士论文

【摘要】：结构损伤识别技术和模态参数识别技术从诞生之日起,就是为了解决实际工程中的问题,因此其具有较高的实用价值和现实的工程背景。模态参数识别和结构损伤识别技术被越来越多的应用于对结构的损伤诊断和健康监测,并且受到越来越多的重视,也逐渐开始成为工程研究领域的热点。钢筋的锈蚀损伤不仅仅会降低结构的使用寿命,更会降低结构的稳定性。在土木工程中,混凝土与钢筋之间产生的粘结强度退化和结构裂缝的产生,一般都是由钢筋的锈蚀所引起的。通过对钢筋锈蚀前后的钢筋混凝土结构动力特性的变化的研究,可以为工程中钢筋混凝土结构的损伤检测提供科学的依据。本文依据法拉第定律,对钢筋采用通电加速锈蚀的试验方法,一共获得了六根产生钢筋锈蚀的试验梁。在锈蚀过程中,将钢筋的锈蚀按照锈蚀率分为0%,5%,10%和15%四个阶段,通过四种钢筋的锈蚀阶段,研究钢筋锈蚀对结构的阻尼比和固有频率的影响。本文的主要研究内容如下:1)设计并浇筑了试验用的钢筋混凝土结构T形梁,同时对钢筋的锈蚀装置也进行了设计。根据法拉第定律,计算得到了在不同的锈蚀程度下,锈蚀所需要的电流密度、电流大小和通电时间。同时在钢筋锈蚀前,通过对试验梁进行处理,成功的控制了钢筋的锈蚀区域和锈蚀程度。2)利用悬臂梁自由振动的衰减特性,采用振动测试的方法,在钢筋的锈蚀率为0%,5%、10%和15%四个阶段时,对悬臂梁进行模态测试,同时对结构的响应信号进行傅里叶变换处理,得到了试验梁在不同锈蚀率下的阻尼比和固有频率。3)取出锈蚀的钢筋并进行清洗处理和称重,发现在实验过程中钢筋的实际锈蚀率是在理论值附近,这表明在实验中成功的控制了钢筋的锈蚀程度,同时通过目测发现人为控制钢筋锈蚀区域的方法也是有效可行的。4)通过对实验所得数据进行处理和分析,发现钢筋混凝土试验梁的阻尼比随着钢筋锈蚀程度的加深而增大,呈上升趋势;试验梁的固有频率随着钢筋锈蚀程度的加深而减小,并且呈减小趋势。对试验数据进行分析发现,钢筋锈蚀对结构的动力特性有着非常显著的影响。5)利用ANSYS建模软件,采用有限元的方法,对钢筋不同锈蚀程度下的钢筋混凝土结构的动力特性进行了数值模拟计算,并将数值模拟的结果同实验的结果进行比较和分析,最后发现数值模拟计算出来的固有频率结果与实验所得的固有频率结果相近。本文的研究结果显示,钢筋锈蚀对结构的动力特性有着非常显著的影响。同时也表明,通过利用结构的自由振动衰减特性,采用振动测试的方法所测得的阻尼比和固有频率,是能够作为诊断指标用于对结构锈蚀损伤的损伤识别中。
[Abstract]:Structural damage identification technology and modal parameter identification technology from the date of birth, is to solve the problems in practical engineering, so it has higher practical value and practical engineering background. Modal parameter identification and structural damage identification technology are more and more used in structural damage diagnosis and health monitoring. More and more attention has been paid to modal parameter identification and structural damage identification technology, which has gradually become a hot topic in the field of engineering research. Corrosion damage of steel bars will not only reduce the service life of the structure, but also reduce the stability of the structure. In civil engineering, the degradation of bond strength between concrete and steel bar and the formation of structural cracks are generally caused by the corrosion of steel bar. Through the study of the dynamic characteristics of reinforced concrete structures before and after corrosion, it can provide a scientific basis for the damage detection of reinforced concrete structures in engineering. According to Faraday's law, the test method of electric accelerated corrosion of steel bar is adopted in this paper, and six test beams producing corrosion of steel bar are obtained. In the process of corrosion, the corrosion of steel bar is divided into four stages according to the corrosion rate: 10% and 15%. Through the corrosion stage of four kinds of steel bar, the influence of corrosion on damping ratio and natural frequency of the structure is studied. The main research contents of this paper are as follows: (1) the T-shaped beam of reinforced concrete structure is designed and poured, and the corrosion device of steel bar is also designed. According to Faraday's law, the current density, current size and electrification time of corrosion are calculated under different corrosion degrees. At the same time, before the corrosion of steel bar, the corrosion area and corrosion degree of steel bar are successfully controlled by the treatment of the test beam, and the vibration test method is adopted by using the attenuation characteristic of the free vibration of the cantilever beam. When the corrosion rate of steel bar is 10% and 15% respectively, the cantilever beam is tested in mode, and the response signal of the structure is processed by Fourier transform. The damping ratio and natural frequency of the test beam under different corrosion rates are obtained. The corroded steel bars are removed, cleaned and weighed. It is found that the actual corrosion rate of the steel bars is near the theoretical value in the experimental process. This indicates that the degree of corrosion of steel bar is controlled successfully in the experiment, and the method of artificial controlling the corrosion area of steel bar by visual inspection is also effective and feasible. 4) by processing and analyzing the data obtained from the experiment, It is found that the damping ratio of reinforced concrete test beams increases with the deepening of corrosion degree of steel bars, and the natural frequency of test beams decreases and decreases with the deepening of corrosion degree of steel bars. By analyzing the test data, it is found that the corrosion of steel bar has a very significant effect on the dynamic characteristics of the structure. 5) using ANSYS modeling software, the finite element method is used. The dynamic characteristics of reinforced concrete structures with different corrosion degree are numerically simulated, and the results of numerical simulation are compared and analyzed with the experimental results. Finally, it is found that the numerical simulation results of the natural frequencies are close to the experimental ones. The results of this paper show that the corrosion of steel bar has a very significant effect on the dynamic characteristics of the structure. It is also shown that the damping ratio and natural frequency obtained by using the method of vibration measurement can be used as diagnostic indexes to identify the structural corrosion damage by using the free vibration attenuation characteristics of the structure.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU375;TU317

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