Dynamic identification and seismic damage accumulation effects in masonry bell-towers

Historic masonry bell-towers, due to their high slenderness and mass are extremely sensible to the effects of the seismic loadings. Another element that contributes to their high vulnerability is the possible presence of a previous damage or the effects of damage accumulation during a seismic sequence. This paper focuses on the effects of damage accumulation through the discussion of a specific case study. In a first part of the paper, thanks to the construction of an Artificial Neural Network, the dynamic behavior of the bell-tower case study is identified based on the results of an experimental investigation. In a second part, the identified numerical model is first used to perform and compares static and time-history nonlinear analyses. Subsequently, the two types of analyses are combined by submitting the structure to a pushover analysis after a time-history analysis (in order to take into account the occurrence of damage). Depending on the accelerogram employed and its peak acceleration, it is possible, by tracing the different pushover curves, to evaluate the worsening of the seismic capacity of the structure