A laboratory test aimed at demonstrating the potential of an Interferometric Radar to estimate the Seismic Risk of damaged buildings

Abstract

In the last decade, the use of interferometric Real Aperture Radar (RAR) to carry out the survey of static and dynamical behaviour of civil structures, such as bridges, consolidated. In the case of urban buildings, due to the small amplitude of vibration, and the high complexity of the radar survey of these structures, a few case studies have been published. Nonetheless, recently some researchers discussed the potential of measuring the frequency of vibration of a building after a seismic event to estimate the occurred damage using this non-invasive and remote sensing technique. This study reports on the results of an experiment carried out to investigate the potential of this application through a laboratory setup. A framed metal structure, composed of bars fastened with bolts, representing a scaled reproduction of a civil building, is monitored using a portable K band (24 GHz) radar interferometer. In the experiment, the structure is monitored by the radar step by step while its stiffness is decreased by loosening, in different points, the bolts constraining the structure; this procedure aims at simulating an increasing damage. Simultaneously to the radar acquisitions, data from a setup of accelerometers mounted on the framed structure are also acquired. Despite the high environmental noise (radar clutter) caused by multiple reflections generated by the neighbour walls and furniture elements internal to the laboratory, the spectral analysis of the displacement samples retrieved from radar acquisitions and from the accelerometers allow to estimate the main vibrating frequencies and finally confirm the expected behaviour. © 2024 11th European Workshop on Structural Health Monitoring, EWSHM 2024. All rights reserved.