Monitoring dynamic and quasi-static deformations of large flexible engineering structures with GPS: Accuracy, limitations and promises

During the last few years the kinematic versions (real time kinematic (RTK) and post-processing kinematic (PPK) modes) of the satellite Global Positioning System (GPS) have been used to monitor quasi-static and dynamic deformations of large slender engineering structures. However, the accuracy of the method, the outlier level (including missed and false alarms) and its limitations have not been statistically determined. For this reason we made a large number of experiments, in which harmonic movements were simulated by a rotating GPS receiver antenna, and the recorded coordinates were compared with the real ones. The outcome of this study is that in mid-latitude regions (phi < 50 degrees) a simple monitoring system consisting of two GPS receivers and a commercial data processing software permits a standard accuracy of up to 15 mm and 35 mm in horizontal and vertical coordinates, respectively, at 1.5% outlier level. Harmonic frequencies in the range 0.1 Hz < f < 0.5 Hz to approximately 2 Hz can also be determined. Summarizing previous research, an outcome of this study is that GPS results can be confirmed by accelerometer data and can shed light on problems such as Karman vortex vibrations, earthquake-induced oscillations and quasi-static deformations of most slender engineering structures. In addition, the GPS may prove very useful in view of recent trends for displacement deformation-based antiseismic design. (c) 2006 Elsevier Ltd. All rights reserved.