PSI - Issue 84

Gianluca Centofanti et al. / Procedia Structural Integrity 84 (2026) 1339–1346

1346

Consequently, defining two subgroups that collect the sensors of decks 2–3 and 4–5 could represent an effective strategy for obtaining diagonal Modal Assurance Criterion (MAC) matrices. However, this choice would have a significant impact on the control charts. Indeed, if for any reason the frequency of one of the two spans were to shift, the coupling would be lost, leading to a substantial variation in the modal vector and to the loss of mode tracking. In the control charts, this would result in tracking losses rather than in the detection of modal anomalies; moreover, if such losses were not sufficient to invalidate the control chart, the affected modes would be replaced by predicted modes without any anomaly warning. In light of these considerations, it is deemed more appropriate to subdivide the deck into subgroups corresponding to individual spans, despite this choice leading to the presence of numerous repeated modes and to non-diagonal MAC matrices. 3. Conclusions The paper presented some of the most frequent cases observed in the analysis of the first 249 structures within the ANAS SHM P3P platform. The results highlight how the definition of subgroups represents a parameter that can be exploited by the analyst to optimise the quality of the analyses, as well as to improve the efficiency of the resulting control charts. It has also been shown that the number of sensors included within a subgroup may slow down continuous identification procedures due to the excessive computational burden imposed on field PCs. The case studies discussed currently cover the majority of the structures managed within the platform, with the exception of some more specific typologies, such as arch bridges and cable-stayed bridges, which nevertheless represent a minority of the assets managed by ANAS S.p.A. Future developments include the validation of the proposed schemes as the number of analysed cases increases, as well as the optimisation of subgroup management with respect to computational effort. Acknowledgements The authors gratefully acknowledge ANAS S.p.A. for providing access to monitoring data and technical documentation related to the source bridge. This study was supported by FABRE - ‘‘Research consortium for the evaluation and monitoring of bridges, viaducts and other structures’’ (www.consorziofabre.it/en) within the activities of the FABRE-ANAS 2021–2026 research program. Any opinion expressed in this paper does not necessarily reflect the views of the funders. References Andreose, F., Borlenghi, P., Chellini, G., Faleschini, F., Garcìa-Macìas, E., Gentile, C., Lepori, L., Mariani, F., Mannella, P., Pellegrino, C., Ruccolo, A., Salvatore, W., Tomassini, E., Ubertini, F., Venanzi, I., Zanini, M.A., 2024. 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