基于高速摄像机的桥梁自振频率测定方法研究

发布时间：2018-06-08 12:05

本文选题：自振特性 + 高速摄像机　；参考：《华南理工大学》2016年硕士论文

【摘要】：鉴于桥梁在国民经济和人民生活中所发挥的重大作用,桥梁结构的健康维护和保障已成为现代工程技术人员的重要研究方向。随着运营时间的增长和车流量的增加,桥梁结构会产生不同程度的损伤,从而严重影响结构的安全性和耐久性。桥梁结构的自振特性可以反映桥梁结构的整体刚度,基于自振特性的模态参数能够有效识别桥梁的损伤情况,所以研究一种更加方便、智能的桥梁自振特性测试方法具有一定的实际意义。本文首先总结了桥梁在动力测试中,桥梁动位移的常用测量方法及其优缺点,结合数字图像处理技术,研究基于高速摄像技术的桥梁动态位移测量方法。在实验室内,采用秒表进行了高速摄像机拍摄频率的标定,以采集的时间间隔和消耗的总时间来评价拍摄频率的稳定性,试验结果表明,在静态实验中,位移误差都在毫米级;本文还使用高速摄像机做了悬臂梁结构的一维运动的监测实验研究,对角度、距离、测点、采集频率、悬臂梁结构的长度采取控制变量的研究方法,采集测点在振动下的图像。然后通过图像处理相关方法,得到测点的坐标像素值,并计算坐标的像素变化值;把像素单位通过标定的比例换算成长度单位,获得测点的位移,并绘制出位移时程曲线。对其中的数据采用FFT频域分析,可获得结构的一阶振动频率,和理论值对比,误差极小。试验结果表明,该方法在环境合适的条件下,方便,精度很高。为了验证基于高速摄像技术的桥梁动态位移测量方法的实际工程可行性,本文选取某在役城市桥梁,分别以DH5922动态测试仪和高速摄像机同步采集桥梁自振信息,将两种测试方法的结果与理论计算值进行对比分析。结果表明,动态测试仪测试值接近工程经验值,高速摄像机的数字图像法能有效识别出主频,峰值也很明显,但是受外界环境的干扰,测试值与工程经验值有差距。分析其原因,脉动风、其它外界干扰容易造成摄像机的基站振动。本文的研究对数字图像法在实际工程运用中具有一定的参考借鉴意义。
[Abstract]:In view of the important role played by the bridge in the national economy and people's life, the health maintenance and guarantee of the bridge structure has become an important research direction of the modern engineering technicians. With the increase of the operation time and the increase of the traffic flow, the bridge structure will produce different degrees of damage, which seriously affects the safety and durability of the structure. The self vibration characteristics of the bridge structure can reflect the overall stiffness of the bridge structure, and the modal parameters based on the natural vibration characteristics can effectively identify the damage of the bridge. So it is of certain practical significance to study a more convenient and intelligent test method for the self vibration characteristics of the bridge. A method of measuring the dynamic displacement of Bridges Based on high speed camera technology is studied by using the digital image processing technology. In the laboratory, a stopwatch is used to calibrate the shooting frequency of the high speed camera. The stability of the frequency is evaluated by the time interval and the total time consumed. The results show that the displacement error is in the millimeter level in the static experiment. In this paper, a high speed camera is used to monitor the one-dimensional motion of the cantilever beam, and the angle, distance, measuring point, acquisition frequency, and the length of the cantilever beam structure are studied by the method of controlling the length of the cantilever beam. The coordinate pixel value of the measured point is obtained and the pixel change value of the coordinate is calculated. The displacement of the measured point is obtained by converting the pixel unit into the growth degree by the calibration ratio, and the position shift time curve is drawn. The first order vibration frequency of the structure can be obtained by FFT frequency domain analysis. The error is compared with the theoretical value, and the error is very good. The experimental results show that the method is convenient and accurate under suitable environment. In order to verify the practical engineering feasibility of bridge dynamic displacement measurement method based on high speed camera technology, this paper selects two kinds of bridges in the service city by using DH5922 dynamic tester and high speed camera to synchronize the self vibration information of bridge. The result of the test method is compared with the theoretical value. The results show that the test value of the dynamic tester is close to the engineering experience value. The digital image method of the high speed camera can effectively identify the main frequency and the peak value is very obvious. However, the test value is different from the engineering test value because of the disturbance of the external environment. Interference can easily cause the vibration of the base station of the camera. The research in this paper has a certain reference value for the application of the digital image method in practical engineering.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U441.3

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