Dynamic monitoring for the structural assessment of a historic masonry tower

The paper describes the experimental procedures applied to assess the structural condition and the seismic vulnerability of the "Gabbia" tower in Mantua, after the seismic sequence of Spring 2012. An extensive diagnostic campaign was carried, between July and October 2012, to support the future preservation actions. The experimental investigation (including direct survey, historic and documentary research, testing of materials and ambient vibration tests) highlighted the poor state of preservation of the upper part of the building and suggested the installation of a dynamic monitoring system in the tower to check the possible evolution of the structural behaviour. After a brief description of the tower and the preliminary survey, the paper presents the monitoring results for a period of 6 months, demonstrating the practical feasibility of damage detection methods based on natural frequencies shifts and the key role of permanent dynamic monitoring in the diagnosis of the investigated historic building.