Dynamic Monitoring of a Mid-Rise Building by Real-Aperture Radar Interferometer: Advantages and Limitations

Abstract

In this paper, remote and in situ techniques to estimate the dynamic response of a building to ambient vibration are reported: data acquired through a real-aperture radar (RAR) interferometer and conventional accelerometers are analyzed. A five-story reinforced concrete housing building, which was damaged during the May 11th 2011 Lorca (Spain) earthquake, is used as a case study. The building was monitored using both types of instruments. The dynamic properties of the building are estimated first taking acceleration measurements using a set of 10 high-precision accelerometers installed on the roof of the building. Further, the displacement–time histories, recorded with the RAR device pointing to a corner of the building, are analyzed. Then, the ability and shortcomings of RAR measurements to deal with the fundamental frequencies of vibration of the structure are investigated. The advantages and limitations of from-inside (accelerometric) and from-outside (RAR) measurements are highlighted and discussed. A relevant conclusion is that, after strong earthquakes, RAR may be an interesting and useful tool, as it allows surveying the structural response of mid-rise buildings remotely, without the need to enter the structures, which may be dangerous for inspectors or technicians in cases of severely damaged buildings. Given that the instrumented building suffered significant damage, the ability of these kinds of measurements to detect damage is also discussed.

Structural displacement monitoring using ground-based synthetic aperture radar

“…GBRAR systems can be suitable for continuously monitoring fast structural displacements, such as mechanical vibration, with a data acquisition rate of a fraction of a second (Rodrigues and Li, 2021). To this end, various case studies, such as bridges (Huang et al, 2020) and buildings (Alva et al, 2020), have been investigated to evaluate GBRAR capabilities for SHM. A study on the feasibility of vibration monitoring of tall structures by combining a laser scanner and GBRAR was presented by Artese and Nico (2020).…”

GPS-Based Network Synchronization of Wireless Sensors for Extracting Propagation of Disturbance on Structural Systems

“…The study of acceleration or vibration is another relevant method to compute the dynamic performance of structures [ 6 , 18 , 19 ]. However, most of the research on vibration extraction is developed with the help of acceleration devices or vibrometers.…”

Operational modal analysis and continuous dynamic monitoring of high‐rise building based on wireless distributed synchronized data acquisition system

“…Nico et al 12 measured the displacements of telecommunications towers by a ground‐based radar interferometry and identified the structural frequencies. Alva et al used a real‐aperture radar to perform displacement‐based dynamic monitoring under environmental excitations to estimate the fundamental frequency of a damaged mid‐rise building 13 . Sofi et al 14 employed an interferometric radar system to determine dynamic characteristics of high‐rise buildings.…”

“…Alva et al used a real-aperture radar to perform displacement-based dynamic monitoring under environmental excitations to estimate the fundamental frequency of a damaged mid-rise building. 13 Sofi et al 14 employed an interferometric radar system to determine dynamic characteristics of high-rise buildings. However, it was reported that the interferometric radar system was sensitive to ambient noise and it is difficult to identify the modal parameters in high orders.…”