NUMERICAL PROCEDURE FOR THE ASSESSMENT OF THE MECHANICAL BEHAVOIUR OF BELL TOWERS

During the past seismic events, the historical bell towers have been highly damaged due to their slenderness and geometrical features. The main characteristics of these structures are the high value of the ratio between the total height and the side length, the existence of significant openings and, usually, of one or more connections to the main religious building. Several studies have been conducted on such structural typology because of the great number of such structures in the European territory and of their high seismic vulnerability. The estimation of the modal parameters plays a key role in the seismic analysis of such structures which can be obtained by performing dynamic tests and by validating a numerical model based on the experimental results. The present paper aims to discuss the effect of a different level of complexity of the experimental setup and, consequently, of the numerical model which is defined to assess the unknown mechanical parameters. The paper highlights that the estimated modal parameters identified on simplified setup configurations can be utilised to assess the bell tower mechanical properties with good accuracy depending on the level of constraint due to the surrounding buildings. The analysis makes use of the case study of a masonry bell tower located in the South of Italy which is characterised by confining building on three facades for about a third of its total height.