Ambient Vibrations of Age-old Masonry Towers: Results of Long-term Dynamic Monitoring in the Historic Centre of Lucca

ABSTRACT

The paper presents the results of an ambient vibration monitoring campaign conducted on the so-called “Clock Tower” (Torre delle Ore), one of the best known and most visited monuments in the historic centre of Lucca. The vibrations of the tower were continuously monitored from November 2017 to March 2018 using high-sensitivity instrumentation. In particular, four seismic stations provided by the Istituto Nazionale di Geofisica e Vulcanologia and two three-axial accelerometers developed by AGI S.r.l., spin-off of the National Institute for Astrophysics, were installed on the tower. The measured vibration level was generally very low, since the structure lies in the middle of a limited traffic area. Nevertheless, the availability of two different types of highly sensitive and accurate instruments allowed the authors to follow the dynamic behaviour of the tower during the entire monitoring period and has moreover provided cross-validation of the results.

Keywords:

• masonry towers
• long-term monitoring
• vibration sources
• operational modal analysis
• environmental effects

Acknowledgements

This research has been partially supported by the Fondazione Cassa di Risparmio di Lucca (TITANIO project, 2016-2018) and the Region of Tuscany and MIUR (MOSCARDO project 2016-2018, FAR-FAS 2014). These supports are gratefully acknowledged.

Disclosure statement

No potential conflict of interest was reported by the authors.