Structural health monitoring and risk assessment of bridges integrating InSAR and a calibrated FE model

During the last decade, Interferometric Synthetic Aperture Radar (InSAR) technology has taken a relevant position in the Structural Health Monitoring (SHM) of built infrastructure as bridges. However, it is still necessary to improve the interpretation of InSAR in the structural evaluation of bridges. Within this context, the capabilities of InSAR for monitoring remotely large zones is one of its main advantages. Then, it could be developed a decision support system for better inspection, maintenance, and rehabilitation plan of bridges that are part of transportation infrastructure systems. Considering the above-mentioned capabilities of InSAR in bridge inspection, in this paper, an alternative risk assessment methodology is proposed to estimate a safety index of bridges using the InSAR time series and a calibrated FE model. The methodology consists of calculating the probability of overpassing some limits calculated by applying stress limits to a FE model following the AASHTO manual. The proposed limits were for service, fracture, and the last one with respect to the statistical value estimated from a reference period of displacements. In the case of the statistical threshold, it was calculated using an inverse process, which means to apply the displacements in the FE model for determining the resulting stress values. This evaluation was developed in the upper fiber of the zone that presents the highest load demand. The implementation of the method using images from Sentinel-1 is demonstrated by the evaluation of the El Carrizo Bridge, which is a cable-stayed bridge that suffered severe structural damage due to a vehicular accident back in 2018. Right after the accident, the El Carrizo Bridge was properly repaired and rehabilitated. With the implementation of InSAR, some of the main findings after the rehabilitation process indicate a relatively low probability of risk. In general, the risk for the next 10 years extracted was under 20%. The resulting stress value was equal to 2.59 MPa, the service limit tensile stress was 3.13 MPa, and the stress fracture was 3.95 MPa. This indicated that the structure is working in an adequate way in terms of operational conditions validating the results obtained based on the proposed methodology.