Detection of Building Response Changes Using Deconvolution Interferometry: A Case Study in Bogota, Colombia

Seismic structural health monitoring allows for the continuous evaluation of engineering structures by monitoring changes in the structural response that can potentially localize associated damage that has occurred. For the first time in Colombia, a permanent and continuous monitoring network has been deployed in a 14-story ecofriendly steel-frame building combined with a reinforced concrete structure in downtown Bogota. The six three-component ETNA-2 accelerometers recorded continuously for 225 days between July 2019 and February 2020. We use deconvolution-based seismic interferometry to calculate the impulse response function (IRF) using earthquake and ambient-vibration data and a stretching technique to estimate velocity variations before and after the Ml 6.0 Mesetas earthquake and its aftershock sequence. A consistent and probably permanent velocity variation (2% reduction) is detected for the building using ambient-vibration data. In contrast, a 10% velocity reduction is observed just after the mainshock using earthquake-based IRFs showing a quick recovery to about 2%. A combination of both earthquake-based and ambient-vibration-based deconvolution interferometry provides a more complete picture of the state of health of engineering structures.

Structural assessment of bridges through ambient noise deconvolution interferometry: application to the lateral dynamic behaviour of a RC multi-span viaduct

Operational Modal Analysis (OMA) is becoming a mature and widespread technique for Structural Health Monitoring (SHM) of engineering structures. Nonetheless, while proved effective for global damage assessment, OMA-based techniques can hardly detect local damage with little effect upon the modal signatures of the system. In this context, recent research studies advocate for the use of wave propagation methods as complementary to OMA to achieve local damage identification capabilities. Specifically, promising results have been reported when applied to building-like structures, although the application of Seismic Interferometry to other structural typologies remains unexplored. In this light, this work proposes for the first time in the literature the use of ambient noise deconvolution interferometry (ANDI) to the structural assessment of long bridge structures. The proposed approach is exemplified with an application case study of a multi-span reinforced-concrete (RC) viaduct: the Chiaravalle viaduct in Marche Region, Italy. To this aim, ambient vibration tests were performed on February 4$$^{\text {th}}$$ th and 7$$^{\text {th}}$$ th 2020 to evaluate the lateral and longitudinal dynamic behaviour of the viaduct. The recorded ambient accelerations are exploited to identify the modal features and wave propagation properties of the viaduct by OMA and ANDI, respectively. Additionally, a numerical model of the bridge is constructed to interpret the experimentally identified waveforms, and used to illustrate the potentials of ANDI for the identification of local damage in the piers of the bridge. The presented results evidence that ANDI may offer features that are quite sensitive to damage in the bridge substructure, which are often hardly identifiable by OMA.

Synergistic application of operational modal analysis and ambient noise deconvolution interferometry for structural and damage identification in historic masonry structures: three case studies of Italian architectural heritage

Conservation techniques within the framework of structural health monitoring, particularly through dynamic measurements and operational modal analysis, are becoming popular for condition-based maintenance and decision-making in historic structures. Nonetheless, while effective for giving insight into the overall behaviour of structures, these techniques may fail at detecting local damages with limited effects on the modal features of the system. In this regard, the analysis of propagating waves throughout the structure poses an attractive alternative for data-driven damage identification. Specifically, some encouraging results have been reported on the application of seismic interferometry to reinforced concrete structures, albeit the number of works concerning ambient vibrations is far scarce, and practically nonexistent in the realm of historic structures. In this light, this article explores the synergistic application of operational modal analysis and ambient noise deconvolution interferometry for the structural identification of historic structures through three different case studies, namely the Sciri Tower in Perugia, the Consoli Palace in Gubbio and the bell-tower of the Basilica of San Pietro in Perugia. The first case study represents a typical example of a masonry tower inserted into a building aggregate, while the second one constitutes a particular case of a monumental masonry palace. The presented results and discussion cover diverse aspects of the identification of wave velocities, signal processing strategies, effects of dispersion and robustness of the identification. Finally, the case study of the bell-tower of the Basilica of San Pietro illustrates the application of operational modal analysis and deconvolution interferometry for damage identification. To do so, two different ambient vibration tests conducted before and after the 2016 Central Italy seismic sequence are studied. The results show concentrated reductions in the wave velocities in the area of the belfry, which demonstrates that deconvolution interferometry constitutes a complementary technique to operational modal analysis for damage localization and, to some extent, damage quantification.