Ambient-noise measurements for seismic risk mitigation of school buildings

Abstract: Seismic risk management of relevant and strategic structures is a notable issue in seismic Italian codes. In order to delineate a rational strategy for seismic risk mitigation on a wide territory, it is necessary to create some decision-making tools useful to define a prioritization of intervention. For this purpose, useful data have to be collected for each structure involved on the territory. The method of ambient-noise measurement on the structure, that is a rapid and cheap technique for acquiring directly the data, is presented in this work. This technique permits to analyse the data within an holistic framework, considering both site effects and structural dynamical characteristics. It is therefore possible to check the presence of some vulnerability parameters that can increase the propension to damage of the building. These parameters are both connected to site amplification factors and to structural seismic behavior, that can heighten the stresses on particular structural elements. Further, joined analysis of site and structure permits to identify the presence of double resonance effects, that are known to be perilous for the structure. Some example of application of the method are presented for school buildings of Friuli Venezia Giulia Region (NE of Italy), that have been analysed during ASSESS project.