Semiempirical Formulations for Estimating the Main Frequency of Slender Masonry Towers

The paper focuses on the analysis of the outcomes of some experimental tests carried out in San Gimignano (Siena, Italy), aimed at measuring the natural frequencies of the medieval masonry towers still present in the historic city center. Information on the investigated towers was inserted into a wider database that collected dynamic, mechanical, and geometrical features of masonry towers. A large amount of data was collected from a literature review, then summing up as many as 43 different case studies. Collected data were then used to identify the main physical parameters influencing the dynamic behavior of slender masonry towers and to critically evaluate the existing empirical formulations proposed for the estimation of the first natural frequency of such structural typology. Correlations between fundamental frequencies and the geometric characteristics and mechanical parameters are discussed, and a novel semiempirical formulation is eventually proposed for a reliable prediction of the main frequency of slender masonry towers.