| Abstract | Many bridges around the world are in urgent need of refurbishment and face challenges of limited capital investment and condition assessment. Public transportation agencies need reliable monitoring technologies to provide advance warnings of performance loss and pending failure of their critical assets, probability of which may increase due to climate change and extreme weather events. Satellites can be used to address some of these issues by taking several images of a bridge structure at different times and analyzing them with advanced processing techniques such as Interferometric Synthetic Aperture Radar (InSAR). With this approach, accurate weather-independent displacement measurements can be obtained to complement scheduled visual inspection data for bridge performance assessment. This paper presents the InSAR methodology with application to a major bridge in Montreal, Canada, namely the historic Victoria Bridge over which acquired satellite images have been validated against analytical and numerical predictions. A new calculation methodology is presented for the validation of satellite displacement measurements and their comparison to predefined thresholds in order to identify the extent and location of excessive motion on the bridge structure. The displacement results of interest include linear rate (or velocity) and thermal sensitivity (or thermal expansion rate), where both, taken separately or in combination, are found valuable for an accurate assessment of the bridge structural integrity. Finally, a new software platform called BRIGITAL is presented, which can make use of satellite data for 3D visualization, data analysis, and detection and early warning of excessive bridge displacements, which can help bridge engineers identify hot spots on bridges and take action to avoid possible problems and failures. |
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