SEISMIC HAZARD OF URBAN AREAS: A CASE-STUDY

Abstract. This work deals with the evaluation of the seismic vulnerability of urban areas. The city of Florence has been selected to be the case-study of the analysis. The work is organized in two main parts. The first one consists of the representation of the area hazard. Starting from the PGA of the area, a map of the amplification factors and of the fundamental frequen-cies has been made, by performing an extensive experimental campaign. The second step is focused on the buildings properties, and on the increase in the seismic hazard – and the con-sequent vulnerability – due to the possible occurrence of resonance. A large data-bank of the buildings has been collected, and they have been classified after their structural material (masonry versus reinforced concrete) and height. As a result of the collected information, a map of the fundamental period of vibration of the buildings has been obtained, by adopting the expressions provided by the current International Codes. The comparison between the pe-riod of each building and the one of its foundation soil has provided the resonance index (RI), which can be considered as an hazard parameter related to each building.