The bell tower of the San Frediano church – Lucca

The Basilica of San Frediano, dating back to the eleventh century, is one of the most fascinating monuments in Lucca, much of its fascination being due to the marvellous mosaics that adorn its façade. During the MONSTER project the bell tower has been fitted by a sensor network able to measure its vibrations during the day. In particular, some low cost accelerometers, developed by the Wireless Networks Lab of ISTI-CNR, have been installed, able to measure the most relevant vibrations of the tower, induced by the swinging of the bells or the traffic in the most busy hours. This instrumentation has been coupled with four high sensitivity seismic stations, made available by the Seismic Observatory of Arezzo (INGV), in order to catch the tower’s smallest movements. Some temperature and humidity sensors integrated the network.

Data coming from the monitorin system have been analysed via some dynamic identification procedures, such as the Stochastic Subspace Identification and the Enhanced Frequency Domain Decomposition method. Finally, a finite-element model of the tower has been created via the NOSA-ITACA code, updated to fit the experimental data and then used to simulate the tower’s response to static and dynamc actions.