The identification of the dynamic properties of a structure is an excellent tool to predict its behaviour following different seismic excitations and to assess its state of health. By recording seismic noise, two different structures were analysed: the medieval bell tower of the church 'Sant'Alessandro, Sisinnio e Martirio' in Angera on the eastern shore of Lago Maggiore (VA) and the chimney of a former industrial site in Porto Tolle (RO). The two buildings differ not only in numerous structural aspects, the most influential of which is the large difference in height -250 m for the chimney vs. 35 m for the bell tower approximately- and the different environmental context in which they are located -relatively isolated for the chimney and urban for the bell tower-, which influences the characteristics of seismic noise, but also in the different design of the seismic monitoring system, which reflects the various aspects that we wish to investigate for the two structures: the influence of the oscillation of the chimney at increasing distances and the dynamic characteristics of the bell tower at increasing heights . The traces obtained from the triaxial velocimeters and accelerometers, used as sensors, were processed using different analysis methods, the results of which led to the identification of the oscillation frequencies, oscillation modes, oscillation directions and oscillation amplitude of the two structures. The following analysis methods were used: spectral analysis, frequency power density analysis (PSD, SVD), spectral H/V ratio, motion analysis (Hodogram) and modal analysis. A further aspect investigated in this thesis is the comparison of the different analyses and the results obtained together with the evaluation of which one may be the optimal or most complete.
L’identificazione delle proprietà dinamiche di una struttura è un ottimo strumento per prevederne il comportamento a seguito di diverse eccitazioni sismiche e per valutarne lo stato di salute. Attraverso la registrazione del rumore sismico, sono state analizzate due diverse strutture: il campanile medievale della chiesa ‘Sant’Alessandro, Sisinnio e Martirio’ ad Angera sulla sponda orientale del Lago Maggiore (VA) e la ciminiera di un ex-sito industriale a Porto Tolle (RO). I due edifici si differenziano oltre che per numerosi aspetti strutturali, di cui il più influente è la elevata differenza di altezza -250 m della ciminiera vs 35m del campanile circa- e per il diverso contesto ambientale in cui sono collocati -relativamente isolato per la ciminiera e urbano per il campanile-, che influenza le caratteristiche del rumore sismico, anche per la diversa progettazione del sistema di monitoraggio sismico che rispecchia i vari aspetti che maggiormente si vogliono indagare per le due strutture: l’influenza dell’oscillazione della ciminiera a distanze crescenti e le caratteristiche dinamiche del campanile ad altezze crescenti . Le tracce ottenute dai velocimetri e accelerometri triassiali, usati come sensori, sono state rielaborate con diversi metodi di analisi ottenendo come risultato le frequenze di oscillazione, i modi di oscillazione, le direzioni di oscillazione e l’ampiezza delle oscillazioni delle due strutture. I metodi di analisi utilizzati sono i seguenti: l’analisi spettrale, l’analisi della densità di potenza delle frequenze (PSD, SVD), il rapporto spettrale H/V, l’analisi del movimento (Hodogram) e l’analisi modale. Un ulteriore aspetto indagato in questa tesi è la comparazione delle diverse analisi e dei risultati ottenuti insieme alla valutazione di quale possa essere quella ottimale o maggiormente completa.
Combinazione di metodi sismici passivi per la caratterizzazione dinamica di edifici alti
NARDI, LETIZIA
2023/2024
Abstract
The identification of the dynamic properties of a structure is an excellent tool to predict its behaviour following different seismic excitations and to assess its state of health. By recording seismic noise, two different structures were analysed: the medieval bell tower of the church 'Sant'Alessandro, Sisinnio e Martirio' in Angera on the eastern shore of Lago Maggiore (VA) and the chimney of a former industrial site in Porto Tolle (RO). The two buildings differ not only in numerous structural aspects, the most influential of which is the large difference in height -250 m for the chimney vs. 35 m for the bell tower approximately- and the different environmental context in which they are located -relatively isolated for the chimney and urban for the bell tower-, which influences the characteristics of seismic noise, but also in the different design of the seismic monitoring system, which reflects the various aspects that we wish to investigate for the two structures: the influence of the oscillation of the chimney at increasing distances and the dynamic characteristics of the bell tower at increasing heights . The traces obtained from the triaxial velocimeters and accelerometers, used as sensors, were processed using different analysis methods, the results of which led to the identification of the oscillation frequencies, oscillation modes, oscillation directions and oscillation amplitude of the two structures. The following analysis methods were used: spectral analysis, frequency power density analysis (PSD, SVD), spectral H/V ratio, motion analysis (Hodogram) and modal analysis. A further aspect investigated in this thesis is the comparison of the different analyses and the results obtained together with the evaluation of which one may be the optimal or most complete.File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.12608/72505