Cost-effective vision-based system for monitoring dynamic response of civil engineering structures

This study develops a cost-effective vision-based displacement measurement system for real-time monitoring of dynamic responses of large-size civil engineering structures such as bridges and buildings. The system simply consists of a low-cost digital camcorder and a notebook computer equipped with digital image-processing software developed in this study. A target panel with predesigned marks is attached to a structure, whose movement is captured by the digital camcorder placed at a fixed point away from the measurement point. The captured images are streamed to the notebook computer and processed by the software to compute displacement in real time. The efficacy of the system in measuring dynamic responses was demonstrated through laboratory tests, seismic shaking table tests on a steel building frame, and a field experiment on a bridge. In order to simultaneously measure displacements of multiple points, this study further developed a time synchronization system, in which TCP/IP protocol is employed for communications. The effectiveness of the time synchronization system was also experimentally verified. The vision-based system developed in this study is simple, cost-effective, easy to install, and capable of real-time measurement of dynamic responses, making the system ideal for monitoring civil engineering structures. Copyright (C) 2009 John Wiley & Sons, Ltd.