Statistical Analysis of Seismic Damage Observed in Historic Masonry Bell Towers

In Italy, the considerable structural vulnerability and large exposure of historic masonry towers combined with the high seismic hazard makes the conservation of these structures a compelling engineering task. The observational data obtained from post-earthquake investigations are valuable sources of information to develop assessment strategies to provide a rapid screening of the structural condition of the investigated buildings. In this context, a database of 129 Italian historic masonry bell towers struck by past seismic events is herein presented, including the EMS98 severity classification of the damage observed in the distinct damage mechanisms, the corresponding seismic events and their characteristics, as well as the tower typology. First, the severities of the observed damage are exploited to quantify the global damage index and extent. Then, the Damage Probability Matrices (DPMs) are developed, not only considering the global damage extents but also accounting for the damage severities observed within each specific damage mechanism. This distinction allows to explore the impact of the individual mechanisms on the global damage. The DPMs are initially presented by considering the earthquake events individually, and, successively, by distinguishing the towers according to their structural typology, i.e., in isolated and bounded.