Soil-Structure Interaction by 3D finite element analyses

In recent years the development of more and more advanced design softwares, able to take into account complex aspects in structural modelling, allows the interaction between the structure and the foundation soil to be properly modelled. Soil-structure interaction is certainly a typical subject but, nevertheless, still new in its applicative aspects. Further studies are necessary for converting the research highlights in practical tools for routine structural analysis. Dynamic soil–structure interaction problems can be treated in different ways; the main distinction is between direct and the substructure approaches. In this work, the F.E. software DIANA (TNO, Delft) has been adopted to solve SSI problems. Soil has been modeled as a 3D elastic medium, discretized by eight-node solid brick elements. In the first stage of the modeling, it was necessary to evaluate the proper sizes of the soil volume to be included in the F.E. model and of the mesh elements. Validation of the developed F.E. model was carried out by comparing the impedances obtained from DIANA analyses to the values provided in literature for shallow foundations. In the final part, the paper illustrates an application of the above procedure on a real building, the Bell Tower of S. Maria del Carmine Church in Na-ples, representative of many other masonry towers present in Italy and vulnerable to seismic loads.