Non-destructive characterization and dynamic identification of a modern heritage building for serviceability seismic analyses

Seismic risk mitigation in urban areas is a very relevant issue in European regions, such as Italy and Greece, characterized by the presence of a large stock of heritage structures. Enhancing the knowledge about the dynamics of structures is definitely useful in view of seismic assessment and design of risk mitigation interventions. However, this task can be difficult in the case of heritage structures, since several uncertainties affect material properties and structural patterns. In this paper, the opportunities provided by dynamic identification techniques for the non-destructive evaluation of heritage structures are discussed with focus on an interesting case study. This refers to the characterization of a modern heritage reinforced concrete building as a preliminary step towards seismic assessment. The structure under investigation is the Tower of the Nations, located in the Mostra D'Oltremare urban park in Naples, Italy. The paper shows how the combination of ambient vibration tests and model refinement can represent a valuable tool for an indirect non-invasive structural assessment of historical structures. Their proper analysis and modeling, in fact, is usually very challenging from the scientific and technical viewpoint due to their unique structural configurations, the several modeling uncertainties and the need to keep destructive investigations very limited. In this framework the present paper shows how a rational choice of the updating parameters and of the objective function can support the model optimization taking into account the ultimate objectives of the analysis, namely the setting of a reliable model for the assessment of the seismic performance of the structure in the linear regime. As a result, the paper describes the refinement of the model of the Tower of the Nations, in a way able to minimize the scatter with the experimental data and, at the same time, enhance the accuracy of response spectrum and seismic time-history linear analyses.