Cyclic numerical analyses of Noto Cathedral: soil-structure interaction modelling

In a country like Italy, characterised by high seismic hazard and vast cultural heritage, the protection of historical monuments against the effects of seismic events is of great importance. the seismic safety of these structures is usually evaluated by disregarding soil-structure interaction, that can instead play an important role. The aim of this paper consists in introducing a simplified approach for taking numerically into account this aspect. Soil-structure interaction in cyclic conditions is taken into consideration by interpreting the foundation system as a macro-element, whose mechanical response is described by an elasto-hypoplastic constitutive relationship. The model allows for both isotropic and kinematic hardening and its constitutive parameters are calibrated with reference to granular soils. It is shown that the numerical implementation of this model in a standard FEM code allows the mechanical response of a 2-D cross section of Noto Cathedral to be realistically reproduced. In particular, the beneficial effect of tie rods connecting footings is highlighted. It is further shown that the cyclic accumulation of vertical settlements under the action of strong earthquakes may eventually lead to footing failure due to vertical force redistribution.