Feasibility of damage/change detection in civil structures by SAR imagery: proof of concept study using SAR simulation

摘要

Abstract: Synthetic Aperture Radar (SAR), capable of all-time and all- weather operation, shows promising applications in monitoring urban areas for earthquake damage detection. The objective of this study is to use a computer code for SAR simulation and to demonstrate the usefulness of SAR applications for identification of seismically induced structural damage. For this purpose, CAD models of several buildings are constructed consisting of a combination of triangular facets, arranged in a way to represent their outside shells. SAR simulation is made in the time-domain using XPATCHT computer code package. Simulated SAR images with highest resolution of 15 cm to the lowest resolution of 2 m are considered. In this simulation, the SAR antenna shoots a bundle of rays with respective angles to the object. After ray tracing, physical optics evaluate the electric field in the far field and the final SAR image is obtained by compressing the simulated data in range and cross- range directions. After obtaining the complex SAR image, magnitude and phase (for interferometry studies) information provide measures in order to identify geometrical changes. The result of the simulation indicates that edges and corners are usually very well detectable and that geometrical changes such as tilting, overturning or pancaking can be observed and measured. !14