Vision-based displacement measurement method for large flexible structures using partitioning approach

Abstract

The horizontal relative displacement of high-rise building structures is the major indicator to the structural safety. It is, however, difficult to directly measure the displacement of flexible high-rise buildings. In this paper, a real-time displacement measurement method for high-rise buildings is presented by means of successive estimation of relative displacement and rotational angle using a multi-channel digital image processing technique. First, two Cameras are installed on ground level aiming at two targets at different floors respectively. At the close target location, additional two Cameras are installed and one of them is aiming the target which is directed by the first Camera, and the other Camera is aiming another target located at higher location than the previous two targets. Since the same target is observed with two Cameras at different floors, the rotational angle at the Camera location in-between can be calculated based on the redundant displacement value together with the information on distances from each Camera to the target. After estimating the rotational angle, the relative displacement measured by each Camera can be reconstructed to global displacement. By using this two-Camera based subsystem in series, the global horizontal displacement at the top floor can be finally obtained. To experimentally verify the effectiveness of the proposed method, several sets of targets and Cameras are installed on a full-scale five-story building frame structure, and a series of the experimental tests are conducted