Image-Based Dynamic Response Measurement of a Full-Scale, Multistory Structure Tested on a Shake Table

Measurement of earthquake engineering-related experimental dynamic testing of structures utilizes conventional devices such as strain gauges, linear variable displacement transducers (LVDT), linear potentiometers (LPT), lasermeters, and accelerometers. These high-speed and high-sensitivity measurement devices possess some disadvantages in terms of their cost-effectiveness, calibration, and installation. Image-based sensing methods could present a viable alternative. This study presents an image-based dynamic response measurement of a full-scale structure tested on a shake table at the University of California San Diego in 2007. A video record of the experiment, as well as dimensions of the test structure and its acceleration data, is available to the public. Using the KLT (Kanade-Lucas-Tomasi) object tracking algorithm method, the displacement measurements were carried out in units of pixel. Since the dimensions of the test structure were provided, measurements were easily scaled to the real displacements. Using numerical derivative operators, velocity and acceleration values were calculated. The success of the image-based method was apparent when the results were compared with the acceleration data recorded in each story level. While the comparison of top floor accelerations was quite successful, such coherency could not be obtained in lower floors and the ground due to camera’s oblique position.