Simplified Vulnerability Assessment of Masonry Bell Towers

Masonry bell towers represent some of the most iconic historical assets of European heritage. However, the typical poor mechanical characteristics of masonry, lack of maintenance and conservation interventions as well as their high slenderness could lead to significant vulnerability against natural actions, such as earthquakes. Given their widespread diffusion in the European and, especially, Italian territories, the seismic vulnerability assessment of such buildings at territorial level can benefit from simplified large-scale methods based on a low amount of input data. Such methodologies, combined with hazard and exposure quantification, are thus adopted for simplified risk analyses leading to the definition of prioritisation rankings aimed at planning intervention activities. In this paper, a novel methodology for fast seismic vulnerability assessment developed by the authors is described. This is formulated as a simplification based on parameter reduction of an existing analytical approach providing a force-based estimation of the structural capacity under horizontal loading. The capacity is then turned into a suitable vulnerability index ranging from zero to one. The methodology is applied to a sample of about 25 bell towers of Naples to perform a preliminary seismic risk analysis by means of purposedly developed fragility curves.