基于数字图像方法的桥梁移动荷载识别

Dynamic Load Recognition of Bridge Based on Digital Image Method

车辆荷载是桥梁安全监测的重要指标之一,如何快速有效地检测出车辆荷载对于桥梁的维护、运营和安全评估有着重大意义.利用数字图像方法,在桥梁中间位置下方布置特征点,通过视频拍摄,利用Otsu对视频分离出的图片进行二值化分析,获取特征点质心的位移变化,转换成桥梁的位移变化,通过位移的变化反演出移动荷载的大小.通过在实验室进行50、70、90、110 kg四种不同荷载单车通过实验,得到实验室桥梁荷载-位移曲线,与接触式顶杆位移计进行对比,对所得到的荷载-位移曲线进行拟合,后通过30 kg和130 kg荷载进行验证,实验证明预估值与实际值误差在3.8%左右;在实桥实验中,该方法能够准确测出有大重量移动荷载经过时产生的位移以及分析其荷载大小.

Vehicle load is one of the important indicators of bridge safety monitoring. How to quickly and effectively detect vehicle loads is of great significance for the maintenance,operation and safety assessment of bridge. Taking advantage of the digital image method,the feature points are arranged below the middle position of the bridge.Through video shooting,the binary analysis of the pictures separated from the video is conducted by Otsu to obtain the displacement change of the centroid of the feature point,which is converted into the displacement change of the bridge. The magnitude of the dynamic load is inversed by the change of the displacement. By conducting bicycle experiments with four different loads of 50,70,90,110 kg in the laboratory,the load-displacement curves of the bridges are obtained. Compared with a contact ejector displacement meter,the resulting load-displacement curve is fitted and verified with loads of 30 kg and 130 kg. The experiments have proved that the error between the estimated value and the actual value is about 3.8%. In the real bridge experiment,this method can accurately measure the displacement of the bridge and analyze its load size when large weight moving load passes.