This thesis will analyze the pavilion of the former Neuro-Psychiatric Hospital of Racconigi named "Chiarugi". The criticality of the structural framework, which has progressively worsened over the years, is essentially due to the poor mechanical characteristics of the substrates present below the laying surface of the foundations which show a liquefaction problem which combined with the relatively shallow hydrometric level of the aquifer has generated a series of differential settlements responsible of the current cracking framework and the most serious and recent collapses. The complex soil-structure interaction will be assessed through a reverse process: normally the first data to start from are the results of the geotechnical investigations to calculate the structure's subsidence, displacements and vibrations; the starting point in this case will instead be the experimental data obtained from a series of accelerometers placed inside the building; the acceleration values, originating from natural vibrations induced for example by the surrounding vehicular traffic or by the wind, have made it possible to trace the structure's ways of vibrating through specific algorithms; the parameters obtained were taken as a reference for calibrating a finite element model.