基于视频图像技术的两不等跨连续梁振动研究

摘要

针对两不等跨连续梁的试验模型,通过视频采集设备录制梁的振动视频,并采用Matlab软件将其振动视频分解成图像,对一系列的图像运用多项式拟合法进行亚像素边缘检测,对由视频得到的梁边缘时域信号进行模态分析,得到连续梁的前三阶振型和频率.将得到的结果与Midas建立的有限元模型分析结果及传统检测结果比对表明,基于视频图像技术的振动分析有较高的精确性.结合规范讨论了计算冲击系数时的频率选择.结果表明:当计算跨中正弯矩效应时冲击系数应该按照《桥规》采用基频计算,在计算中支座负弯矩效应时冲击系数应采用第2阶频率进行计算.%In view of the test model of the two-unequal span continuous beam,the video of the vibration beam is recorded by the video capture device.By using Matlab software,the vibration video is decomposed into a series of images.A polynomial fitting method is used to detect sub-pixel edges for a series of images.The modal analysis of the beam edge time domain signals obtained by the video is carried out and the vibration modes and frequencies of the first three order of the continuous beam are obtained.The obtained results are compared with the analysis results of the finite element model by Midas and the traditional detection results,showing that the vibration analysis based on video image technology has higher accuracy.Combined with the standards,the frequency selection for calculating impact coefficients is discussed.The results show that when calculating the mid-span moment effect,the impact coefficient should be calculated according to the basic frequency of the Bridge Gauge.When the negative moment effect of the bearing is calculated,the second order frequency should be used to calculate the impact coefficient.