Una nuova formulazione semi-empirica per la stima della prima frequenza naturale di torri storiche in muratura

The paper takes advantage of some experimental tests carried out in San Gimignano (Siena, Italy), with the aim to measure the natural frequencies of the medieval masonry towers still present in the historic city centre. These results were increased by means of collecting similar information of a wide amount of historic masonry towers widespread into the whole European territory, thus summing up the geometric, mechanic and dynamic caracteristics of 43 different case studies. These collected data were then used to identify the main physical parameters influencing the dynamic behaviour of slender masonry towers, and to critically evaluate the existing empirical formulations proposed for the estimation of the first natural frequency of such typology of structures. In this paper, correlations between fundamental frequencies and geometric characteristics and mechanical parameters are discussed, and a novel semi-empirical formulation is eventually proposed for a reliable prediction of the main frequency of slender masonry towers.