基于车桥耦合理论的桥梁频率测试方法研究

发布时间：2018-01-24 21:40

本文关键词： 车桥耦合振动快速傅里叶变换桥梁一阶自振频率　出处：《郑州大学》2017年硕士论文　论文类型：学位论文

【摘要】：我国山川密布,河流星罗棋布,桥梁结构众多,大多数中小桥梁由于修建时间较长,长期受到以车辆为主的动荷载作用,很多结构出现了破坏。在桥梁检测过程中,桥梁自振频率是一项重要的指标,而传统直接测量桥梁频率的方法由于过于复杂,而且成本较高,往往费时费力。因此,开展研究一种间接测量桥梁频率的方法是十分必要的。本文就车桥耦合振动过程展开研究,通过对车辆竖向加速度公式进行推导,找到桥梁自振频率与车辆之间的关系,利用快速傅里叶变换对车辆的竖向加速度进行时频转换,从而提取出桥梁的一阶自振频率。利用有限元软件ANSYS对车桥耦合振动进行模拟,分别对车辆的四种模型(移动力、移动质量、单轴弹簧质量、双轴弹簧质量)进行车桥耦合振动模拟计算,提取出桥梁跨中点和车辆的位移、速度和加速度的时程响应。研究了三种不同速度下车桥耦合振动响应。(一)根据MATLAB进行理论计算分析,并与ANSYS进行对比。(二)对得到的车辆竖向加速度进行快速傅里叶变换,提取出桥梁一阶自振频率;通过分别对车辆速度、阻尼、车桥质量比对提取出桥梁自振频率的影响进行研究得出以下三条结论:1.车辆速度对桥梁自振频率提取值有一定的影响;2.阻尼对桥梁自振频率提取值影响很小;3.车桥质量比对桥梁自振频率提取值有很大影响。对小雍庄桥进行跑车试验,采集车辆的加速度信号。车辆分别以10km/h、20km/h和30km/h的速度通过桥梁,共采集了三组车辆数据,然后对其进行快速傅里叶变换。对比模拟值与实测值和直接法测量桥梁自振频率实测频率误差分别为2.550%、6.922%和10.00%;模拟结果误差分别为1.275%、2.185%和3.097%。试验表明提取精度随车速的增加而减小,但总体上满足工程实例要求。因此,建议运用此方法测量桥梁频率时,车辆要满足轻型低速通过桥梁结构的要求。
[Abstract]:Our country is full of mountains and rivers, the bridge structure is numerous, most of the small and medium-sized bridges are subjected to the dynamic load mainly by vehicles for a long time. Many structures have been damaged. In the process of bridge detection, the natural vibration frequency of bridge is an important index, but the traditional method of direct measurement of bridge frequency is too complex, and the cost is high. Therefore, it is necessary to study an indirect method to measure bridge frequency. This paper studies the coupled vibration process of vehicle and bridge, and deduces the vertical acceleration formula of vehicle. The relationship between the natural vibration frequency of the bridge and the vehicle is found, and the vertical acceleration of the vehicle is converted by the fast Fourier transform (FFT). In order to extract the first order natural vibration frequency of the bridge, the coupling vibration of the vehicle and bridge is simulated by the finite element software ANSYS, and the four models (moving force, moving mass, single axle spring mass) of the vehicle are respectively studied. Two-axis spring mass) is used to simulate the vehicle-bridge coupling vibration to extract the midpoint of the bridge span and the displacement of the vehicle. The time history response of velocity and acceleration. The response of vehicle-bridge coupling vibration under three different velocities is studied. (1) the theoretical calculation and analysis are carried out according to MATLAB. Compared with ANSYS, the vertical acceleration of the vehicle is transformed by fast Fourier transform, and the first order natural frequency of the bridge is extracted. By studying the influence of vehicle speed, damping and the ratio of vehicle to bridge mass on the extraction of bridge natural vibration frequency, the following three conclusions are drawn: 1. Vehicle speed has certain influence on bridge natural vibration frequency extraction value; 2. Damping has little effect on the natural vibration frequency of the bridge. 3. The mass ratio of vehicle to bridge has a great influence on the natural vibration frequency of the bridge. The vehicle acceleration signal is collected by the sports car test of Xiaoyongzhuang Bridge. The vehicle takes 10 km / h respectively. At 20 km / h and 30 km / h across the bridge, three sets of vehicle data were collected. Comparing the simulated value with the measured value and the direct method, the measured frequency error of the bridge natural vibration frequency is 2.550% 6.922% and 10.00% respectively. The errors of simulation results are 1.275% and 3.097%, respectively. The experiment shows that the extraction accuracy decreases with the increase of speed, but generally meets the requirements of engineering examples. It is suggested that when using this method to measure bridge frequency, vehicles should meet the requirement of light and low speed passing through bridge structure.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U441.3

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