数字图像技术在三等跨连续梁振动分析中的运用

摘要

In order to demonstrate the reliability and accuracy of the natural frequency and vibration mode of the three-span continuous beam measured by video image method,the vibration video of three-span continuous beam is recorded by video recording equipment,decomposed into a series of images by Matlab software,and use polynomial fitting program making the edge get to the sub-pixel level,obtaining the time history of the points on the beam and performing the modal analysis finally.Then the first three frequencies of the obtained beam and the results obtained by the traditional detection method are compared with the results obtained by analysis of the model by finite element software respectively.The results show that the video image method is effective and reliable to measure the natural frequency and mode of the three-span continuous beam,and is closer to the theoretical calculation than the traditional bridge inspection.%为了论证视频图像法实测三等跨连续梁固有频率和振型的可靠性及精确性,使用视频录制设备录制三等跨连续梁的振动视频,通过Matlab将其分解成一系列图像,并运用多项式拟合程序将边缘精确到其亚像素级别,得到梁上各点的时间历程,最后进行模态分析.将得到的梁的前3阶频率和振型和通过传统检测方法测得的结果,分别与有限元软件建立模型进行模态分析所得到的结果进行误差对比.结果显示视频图像法对测量三等跨连续梁的固有频率及振型是有效可靠的,而且比传统桥梁检测方法更接近理论计算结果.