PSI - Issue 64

Carmelo Gentile et al. / Procedia Structural Integrity 64 (2024) 677–684 Author name / Structural Integrity Procedia 00 (2019) 000–000

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 Eight principal modes of the historical building are detected in the frequency range 0-5 Hz. The automatically identified modes involve the dominant sway of the columns in the transversal (N-S) and longitudinal (E-W) directions of the cathedral.  Daily and seasonal variations affect natural frequencies, possibly influenced by environmental factors. The correlation between natural frequencies and indoor/outdoor temperature is complex: during the cold season, frequencies increase as temperature decreases, whereas in the hot season, most frequencies exhibit a positive correlation with temperature.  The distinctive frequency-temperature correlation is likely influenced by the simultaneous impact of thermal expansion on both metallic ties and masonry: (a) during the cold season the increased tensile stress/force in metallic ties stiffens the building, causing all natural frequencies to increase with decreased temperature; (b) in the hot season, the thermal expansion of the masonry blocks become dominant and causes the increase of the frequencies of most modes (C1, C3-C8) with increased temperature.  The application of a classic frequency-based SHM methodology, involving a novelty analysis approach, did not detect any change in the structural condition of the monument, which was also exposed to a couple of significant seismic events during the investigated monitoring period. Acknowledgements The support of Veneranda Fabbrica del Duomo di Milano and the co-operation of MSc Francesco Canali are gratefully acknowledged. References Alaggio, R., Aloisio, A., Antonacci, E., Cirella, R., 2021. Two-years static and dynamic monitoring of the Santa Maria di Collemaggio basilica. Construction and Building Materials 268. https://doi.org/10.1016/j.conbuildmat.2020.121069 Allemang, R.J., Brown, D.L.,1982. A correlation coefficient for modal vector analysis. In: 1st International Modal Analysis Conference Proceedings, pp. 110-116. Ferrari da Passano, C., 1973. Storia della Veneranda Fabbrica, Cassa di Risparmio delle Province Lombarde, Milan. Ferrari da Passano, C., 1988. Il Duomo rinato. Diakronia, Milan. Gentile, C., Guidobaldi, M., Saisi, A., 2016. One-year dynamic monitoring of a historic tower: damage detection under changing environment. Meccanica 51, 2873-2889. https://doi.org/10.1007/s11012-016-0482-3 Gentile, C., Ruccolo, A., Canali, F., 2019. Continuous monitoring of the Milan Cathedral: dynamic characteristics and vibration-based SHM. J. of Civil Structural Health Monitoring 9, 671-688. https://doi.org/10.1007/s13349-019-00361-8 Jolliffe, I.T., 2002. Principal Component Analysis. Springer, New York. Kita, A., Cavalagli, N., Ubertini, F., 2019. Temperature effects on static and dynamic behavior of Consoli Palace in Gubbio, Italy. Mechanical Systems and Signal Processing 120, 180-202. https://doi.org/10.1016/j.ymssp.2018.10.021 Masciotta, M.G., Roque, J.C.A., Ramos, L.F., Lourenço, P.B., 2016. A multidisciplinary approach to assess the health state of heritage structures: The case study of the Church of Monastery of Jerónimos in Lisbon. Construction and Building Materials 116, 169-187. https://doi.org/10.1016/j.conbuildmat.2016.04.146 Montgomery, D., 2013. Introduction to statistical quality control. John Wiley & Sons Inc. Nava, A., 1845. Relazione dei ristauri intrapresi alla Gran Guglia del Duomo di Milano. Tipografia Valentini, Milan. Pappa, R.S., Elliott, K.B., Schenk, A., 1993. Consistent-mode indicator for the eigensystem realization algorithm. Journal of Guidance, Control, and Dynamics 16, 852-858. https://doi.org/10.2514/3.21092 Peeters, B., De Roeck, G., 1999. Reference-based Stochastic Subspace Identification for output-only modal analysis. Mechanical Systems and Signal Processing 13(6): 855-878. https:// doi. org/ 10. 1006/ mssp.1999.1249 Ramos, L.F., Marques, L., Lourenço, P.B., De Roeck, G., Campos-Costa, A., Roque, J., 2010. Monitoring historical masonry structures with operational modal analysis: Two case studies. Mechanical Systems and Signal Processing 24, 1291–1305. Ubertini, F., Comanducci, G., Cavalagli, N., Laura Pisello, A., Luigi Materazzi, A., Cotana, F., 2017. Environmental effects on natural frequencies of the San Pietro bell tower in Perugia, Italy, and their removal for structural performance assessment. Mechanical Systems and Signal Processing 82, 307-322. https://doi.org/10.1016/j.ymssp.2016.05.025 Veneranda Fabbrica del Duomo, 1885. Annali della Fabbrica del Duomo di Milano: Dall’origine fino al presente. Veneranda Fabbrica del Duomo, Milan.