Structural health monitoring of a historic masonry tower

The paper summarizes the results of the first 15 months of continuous dynamic monitoring of the Gabbia tower in Mantua. After the Italian seismic events of May 2012 a wide investigation program was performed on the tower, suggesting the installation of a dynamic monitoring system in the upper region of the building. The continuously recorded signals allowed the automated identification of the natural frequencies of the key vibration modes of the structure and the clear detection of the effects of temperature on the natural frequencies. The study of the correlation between frequencies and temperature also revealed the non-reversible structural effects determined by a far-field earthquake, proving the effectiveness of damage detection techniques based on frequency shifts.