EXPERIMENTAL INVESTIGATIONS ON THE BELL TOWER OF PIEVE SAN LORENZO

This study presents the diagnostic investigations conducted on the bell tower of Pieve of San Lorenzo in Minucciano, in the Lunigiana region of Tuscany, Italy. The bell tower is an integral part of a complex of great historical and architectural significance. The Lunigiana is characterized by high seismic activity, and several significant earthquakes have affected the bell tower over the years. The structure suffered severe damage in 1920, leading to restoration work after the collapse of its top level. More recently, the 2013 earthquake (Mw 5.2) caused new cracks, particularly in the pillars of the bell chamber, highlighting the need for structural assessment. For these reasons, the tower needed diagnostic investigations to assess its current condition and to plan possible interventions. The investigations were conducted both in situ and at the Structural and Material Testing Laboratory of the Department of Civil and Environmental Engineering of the University of Florence. Among dynamic tests, environmental vibration and sonic tests were carried out. Ambient vibration tests have been performed with accelerometers placed at various levels of the tower along the inner masonry wall. The vibrations of the structure caused by both environmental factors and the bells motion have been recorded. The signals obtained have been then processed and analysed, to determine the tower’s dynamic parameters. Sonic tests have instead been performed on the pillars adjacent to the mullioned windows located near the lower level of the tower’s octagonal section. Beyond assessing the health status of the tower under study, this paper aims to compare the results obtained from the various tests, evaluating their reliability and accuracy, as well as how they complement and integrate with each other for a comprehensive assessment of historical structures.