The Giotto's Bell Tower at Firenze (Italy): foundation assessment

Purpose: The paper is aimed at assessing the safety of the Giotto's Bell Tower, with special attention to its foundation system, i.e. the foundation works and soil. The tower, well known all over the world, has a squared plan, with sides of 14.45 m each, and a total height equal to 84.7 m. The structural response of the tower is assessed with reference to the gravitational load and to the expected seismic action, quantified according to the seismic hazard of the site and the foundation soil. Design/methodology/approach: A simplified analysis has been performed to check the safety level of the tower to seismic actions. Special attention has been paid to quantify the horizontal actions representing the seismic loads. Such quantification, indeed, has been made both through the elastic spectrum of the tower and by performing a site response analysis on the foundation soil, represented as a one-dimensional stratification of soil layers, described on the basis of experimental investigations. After defining the loading actions, a simplified assessment of the foundation safety has been made by considering the action over foundation, the geotechnical data and the safety factor. Findings: The findings of the paper concern the assessment of the safety of the tower's foundation system. A lot of experimental data on the foundation soil, provided by various geological investigations, have been provided and used for the assessment. Moreover, the mechanical properties of the materials used for the structure have been collected and shown in the paper. Originality/value: The paper collects a lot of technical information regarding the Giotto's Bell Tower, both regarding its foundation soil and the constituting materials. On the basis of the collected information, a structural analysis has been made to assess the seismic safety of the tower, and the results of such assessment are provided and discussed.