High-rate real-time PPP for dynamic motion detection in vertical direction

Nowadays, with the developments in GNSS (Global Navigation Satellite System) technology, the data storage and data processing capacity of GPS (Global Positioning System) receivers has been gradually increased. This situation is widely used in the detection and monitoring of horizontal and vertical vibrations that occur in the structure when high temporal resolution geodetic GPS receivers are under the influence of dynamic loads such as earth crust motions, wind load, traffic load, which affect man-made engineering structures. In the study, RT DF-PPP (Real Time Dual Frequency-Precise Point Positioning) method was applied together with a GPS sensor with a sampling interval of 20 Hz, using a steel bar mounted on a steel tree model designed as a structure model, and a steel bar on which different sensors can be integrated and can provide simulation of vertical motions in detecting vertical motions occurring in structures. To evaluate the performance of the method used and to test the performance of capturing vertical displacements, the DF-RP (Dual Frequency-Relative Positioning) method was taken as reference and the results were compared with the PP-PPP (Post Process-PPP) method using the IGS-Final (International GNSS Service-Final) product. When the results are compared with the RP and PP-PPP solutions in the frequency domain of vertical motions as a result of harmonic oscillations of the high-rate RT-PPP method, it has been seen that the amplitudes and frequencies are compatible with each other. Therefore, dynamic motions that occur as a result of natural events such as earthquakes, tsunamis, landslides and volcanic eruptions can be instantly and reliably monitored and detected by the high-rate RT-PPP method. When the results were evaluated in the time domain, an improvement was observed in the RMSE (Root Mean Square Error) and maximum values of RT-PPP and PP-PPP methods according to RP after filtering. When the statistical results are examined, vertical harmonic motions of the solutions made by using both RT-PPP and PP-PPP methods can be detected with accuracy below centimeters. These results clearly show that it can detect vertical dynamic motions in engineering structures such as bridges, skyscrapers and viaducts with RT-PPP method to evaluate. Thus, by detecting the effects of dynamic motions occurring in the structure on the health of the structure, a safe environment will be provided by making a rapid hazard assessment for life safety.