Identification and assessment of the seismic behaviour of Giotto’s bell tower in Florence (Italy)

Among the different typologies of historic buildings, masonry towers represent a hallmark of many European town centres which embody an important heritage to be preserved and passing on to future generations. Giotto’s Bell Tower in Florence together with the Leaning Tower of Pisa and the San Marco Tower in Venice (which collapsed in 1902) is one of the iconic masonry towers ever built in Italy. The assessment of the structural behaviour of these structures, together with the development of proper preservation strategies, has attracted in recent decades the interest of a plethora of scholars. Most of the studies on towers vulnerability focuses on the assessment of their seismic behaviour, since their slenderness exposes them to the dynamic effects induced by medium-to-severe earthquakes. This paper, given this background, discusses the identification and the seismic behaviour of Giotto’s Bell Tower in Florence. In a first part of this paper a refined numerical model, built through the finite element technique based on a recent laser scanning survey, is reported together with the procedure adopted for its modal identification. The finite element model accounts for the soil-structure-interaction. In a second part of this paper the numerical model is employed to perform linear time-history analyses, by using natural accelerograms. The results of the analyses allow to assess the seismic behaviour of the Bell Tower of Giotto and suggest preservation strategies.