Preserving the heritage of world’s monuments through Structural Health Monitoring – A case study: the Garisenda Tower

Abstract

The Italian peninsula has numerous heritage structures, including fifty-five sites registered under the UNESCO World Heritage Convention, living testimonies of the passage of man through times. Heritage structures are subject to aging and impact from the climate, resulting in deterioration of the structural behaviour. These phenomena can significantly reduce their usability, or even undermine the stability, and eventually induce safety, and rehabilitation issues. For those primary reasons, increasing attention is given by local authorities to understand the behaviour of structures and take the right action at the right time. To preserve the cultural heritage, Structural Health Monitoring (SHM) is becoming more important, as it allows to follow the evolution of structural behaviour. The study of meaningful variables allows to identify the activated structural mechanisms and, consequently, implement timely actions against ongoing degradation phenomena. A notable example is represented by the activities undertaken by the Municipality of Bologna on the Torre della Garisenda. The structure is monitored since 2019 to study the behaviour of its basement through measurements collected by deformation and temperature sensors. The installed monitoring system allows to carry out numerous analyses: evaluation of the structural response under dynamic actions, study of the evolution of the static behaviour of the tower and analysis of the effects induced by seasonal thermal variations. Advanced algorithms for data analysis allow to develop critical analysis and interpretation on the obtained results, providing information to support decision making process. Indications on the functionality of the system and typical examples of the collected results are provided.