Parametric analysis on the seismic response of masonry bell towers

The Italy is a country rich of historical buildings, often made up of bricks, which were seriously damaged or suffered collapse after recent devastating earthquakes. In this framework the current work shows the results of instrumental researches and structural analysis aiming at the description of the seismic behaviour of masonry belfries or bell towers. Forty case studies belonging to thirteen Italian regions, so to be representative of the different seismic areas of the country, have been herein examined. A global modelling approach based on macro-elements models able to reproduce the seismic behaviour of bell towers with the support of the equivalent frame technique has been implemented through the 3MURI software. This numerical approach has allowed to reproduce the sequence of the main damage mechanisms of structures as horizontal forces increase. Therefore, a parametric analysis has been performed to evaluate the seismic response of investigated structures by changing their geometrical parameters. From the achieved results the individuation of the bell towers most at risk placed in different parts of Italy (North, Centre and South) has been faced. Finally, a new third order polynomial formula is proposed to calculate the principal vibration period of light squared stone towers as a function of their slenderness.