Continuous dynamic monitoring of historic masonry towers using few accelerometers: methodological aspects and typical results

The paper exemplifies the application of health monitoring using operational modal analysis to two historic masonry towers, built in stonework masonry and solid brick masonry, respectively. In both the presented case studies, simple dynamic monitoring systems (including few accelerometers and temperature sensors) were permanently installed in the upper part of the building and automatic identification of the tower modal parameters was performed. The results allowing to evaluate the effects of changing temperature on automatically identified natural frequencies and to verify the practical feasibility of damage detection methods based on natural frequencies shifts provide clear evidence of the possible key role of continuous dynamic monitoring in the preventive conservation of historic towers.