First Steps Using Two GPS Satellites for Monitoring the Dynamic Behavior of a Small Concrete Highway Bridge

Abstract

This work presents the results of global positioning system (GPS) data processing using the phase residuals method (PRM)—L1 carrier phase from two satellites—to monitor the dynamic behavior of a small concrete bridge. The bridge tested, the Jaguari Bridge, is a small, curvd, reinforced concrete bridge. The bridge over the Jaguari River is a reinforced concrete bridge built in 1999, located on Fernão Dias Highway (BR 381), positioned at Kilometer 946, Minas Gerais, Brazil. The small concrete bridge was chosen for this study because its construction type is found in great numbers throughout Brazil. In parallel, there was a significant increase of pathologies in these structures as a result of lack of maintenance procedures. The detection of small vibrations of spans, for example, which is a good indicator of the health of a structure, can be monitored by GPS. The challenge in this case is trying to detect with GPS the dynamic displacement that has an amplitude close to 5 mm. Application of the PRM on GPS data allowed the detection of this very small dynamic vibration. In addition, this is the first case of success with applying GPS as a tool for monitoring the dynamic behavior of small concrete bridges. The experiment consisted of sessions conducted during 2 days and used two GPS receivers (with a 100-Hz recording rate) over the central span of the Jaguari Bridge in 2014. The continuous wavelet transform (CWT) was used as a filter technique to analyze the frequencies generated by residues from double-difference data processing.