Development of a Finite Element modelling strategy to investigate the soil-structure interaction of the Two Towers in Bologna

This thesis develops a finite element modelling strategy for analysing the soil–structure interaction of the Two Towers of Bologna. The study shows that the behaviour of Asinelli and Garisenda depends not only on their geometry and inclination, but also on the complexity of the supporting subsoil, characterized by fine-grained alluvial deposits, paleosol horizons, and weaker intermediate layers within the foundation influence zone. These conditions require a numerical approach in which towers, foundations, and soil are treated as an interacting system. A staged methodology was implemented in Abaqus. Preliminary two-dimensional analyses were used to verify the modelling workflow and the implementation of mapped fields, while the three-dimensional model allowed a more realistic representation of the stress-transfer mechanisms beneath the foundations. The comparison between linear elastic and Mohr–Coulomb constitutive laws, together with different interface friction coefficients, showed that both factors strongly influence the predicted stress field. The elastic models tend to produce artificial tensile regions, whereas the Mohr–Coulomb model gives a more realistic compressive response through yielding and stress redistribution. The results obtained at the main foundation depths and along selected sections confirm that the stress response beneath Garisenda is strongly influenced by edge loading associated with tower rotation. Fine-tuning of the analysis sequence further reduced artificial positive stresses and improved the physical consistency of the results. Overall, the thesis demonstrates that staged modelling, mapped heterogeneity, and controlled interface conditions provide a robust basis for studying the Two Towers.