Structural monitoring and integrity assessment of medieval towers

This investigation concerns the structural stability of two medieval buildings, “Torre Sineo” and “Torre Astesiano”, rising in the centre of Alba, a characteristic town in Piedmont (Italy). The geometrical and structural aspects of these masonry towers were analysed and tests were performed to assess the evolution of damage phenomena. The slant of the towers was determined with the customary topographic survey methods. Nondestructive testing methods were used, instead, to determine the extent of damage and cracking and to assess the evolution of these phenomena over time. The damage processes underway in some portions of the masonry were monitored using the Acoustic Emission (AE) technique. The latter method makes it possible to estimate the amount of energy released during the fracture process and to obtain information on the criticality of ongoing processes. Finally, an ad hoc theory based on fractal concepts for assessing the stability of masonry structures from the data obtained with the AE technique is proposed.