EUROPEAN GROUND MOTION SERVICE FOR BRIDGE MONITORING: TEMPORAL AND THERMAL DEFORMATION CROSS-CHECK USING COSMO-SKYMED INSAR

Abstract. This paper elaborates on the potential of the deformation time-series provided by European Ground Motion Service (EGMS) data points for bridge monitoring, in terms of the response of bridge structures to temporal and thermal deformations. For this purpose, high-resolution Cosmo-SkyMed (CSK) Synthetic Aperture Radar (SAR) images have been utilized through Persistent Scatterer SAR Interferometry (PS-InSAR) to derive spatially detailed deformation time-series of two bridges located at the north of Lombardy region, Italy. Then, the Annual Displacement Velocity and Thermal Expansion Coefficient of the data points in both datasets are extracted based on the corresponding deformation time-series. The response parameters are post-processed through projection and compensation steps to become comparable. Cross-checking the results by comparing the response parameters along the bridges showed that the global (for L3 products) and local (for L2b products) differential behaviour and the variation of the values of these parameters from one side to the other side of each bridge are consistent between CSK and EGMS datasets. However, the EGMS L3 information shows a slightly lower magnitude in both displacement velocity and thermal expansion coefficient responses. According to the revealed capability of EGMS information in this work, it can be concluded that the EGMS data points, if spatially cover a bridge, can present a reasonable and sufficient insight into the temporal evolution of displacement and thermal structural response, suitable for structural health monitoring and condition assessment of bridges under operational and environmental loads.