Video Tracking of Targets for Vibration Measurement of Large-Scale Structures Under Seismic Excitation

Development of video-based vibration techniques and reliability of displacement measurements have important implications in several areas, including structural testing and monitoring of large structures. Through the use of numerous targets placed on the structure, 3-dimensional (3D) analysis, and modal identification can be performed with minimal installation costs, no mass increase, and contactlessly. This study applies and validates video tracking of targets for vibration analysis of a large-scale structure, namely, a reinforced concrete U-shaped wall, tested experimentally under seismic excitation on a shake table. 2D grids of targets are placed on two orthogonal surfaces and filmed by several cameras. Values obtained from a motion capture system, digital image correlation, and traditional displacement sensors are compared. Results confirm that the 3D motion of the U-shaped wall surfaces and foundation can be accurately extracted from video analysis.