Deformation Monitoring of Posttensioned Bridges Using High-Resolution Satellite Remote Sensing

This study presents the results of spaceborne monitoring of two posttensioned bridges in Virginia. Routine safety inspections revealed extensive cracking in the concrete girders. Problems were traced to the inadequate quality of tendon grouting, resulting in the partially bonded condition. The TerraSAR-X radar satellite, operated by the German Aerospace Center, was used to acquire radar imagery in the Staring SpotLight mode from the ascending and descending orbits at 11-day intervals. The data were processed with the SqueeSAR algorithm, resulting in millimeter-range precision of the time-displacement series. No permanent deformations were detected at the posttensioned segments during the monitoring period of 1.3 years. The high density of the measurement points allowed adequate characterization of bridge displacements. The results of the interferometric analysis attest to the feasibility of implementing satellite-based performance monitoring of bridges, offering an innovative asset management tool that can complement and augment current inspection methods. (C) 2019 American Society of Civil Engineers.