Save what we can: experimentally validated design of stengthening interventions to reduce the seismic vulnerability of a bell-tower

The design of strengthening interventions on historical buildings is complex due to the numerous uncertainties in terms of geometric and mechanical properties. In addition to this, interventions must be critically examined in relation to their effectiveness and to their impact on the conservation of the assets. Accordingly, also in consideration of collapse mechanisms typically observed in historic buildings, a cognitive research must focus primarily on the history of the building, the geometry of various structural elements, construction techniques, as well as material degradation. Difficulties typically connected to knowledge are often in relation to available resources and the invasiveness of the research to be performed, this making necessary to compare by means of posterior models based on the observations and experimental verification of the mechanical behavior of the building. Accordingly, in the field of seismic strengthening interventions, dynamic tests, experimental modal analysis techniques and FE modeling may play an important role. The first two contribute to knowing the actual health state of the historical buildings, while the last is useful to evaluate, since a preliminary design stage, the effectiveness of the interventions. The present paper proposes a rationale for optimizing seismic safety measures and interventions, along with the description of the interesting case study of the bell-tower of the Fossan