GNGTS 2021 - Atti del 39° Convegno Nazionale

353 GNGTS 2021 S essione 2.2 In the present paper, district fragility curves have been developed with reference to a case study of the Saviano municipality, located in the province of Naples (Italy). It is a town having about of 16000 people, a territorial surface about of 14 km 2 and a mean seismic hazard with characterized by a peak-ground acceleration a g =0.178 g (at Ultimate Limit State - ULS). Data for elaborating fragility curves have been provided by the authors within the CarTiS research project. CarTiS is promoted by ReLUIS consortium in collaboration with the Italian Department of Civil Protection (DPC), whose aim consists of elaborating a large database containing information on typological and structural features of Italian buildings. Fig. 2a reports a map of the municipality of Saviano. On this map seven different districts have been identified, with emphasis to the urban center. They have been defined thanks to in situ inspections, which allowed for recognizing the structural-typological building classes present in each district and their number (Tab. 2). Moreover, to have information of structural features of buildings or on typical retrofit interventions adopted in the zone of interest, interviews to local technicians have been also carried out. In Fig. 2b are represented the fragility curves relative to each district of Saviano. Such curves have been obtained through the Log-normal distribution given by the eq. (1). It is characterized by new averages and new standard deviations, both obtained as ‘weighted’ values between those used for defining typological fragility curves and the number of building for each typology. Fragility curves shown in Fig. 2 offer a complete vision of the seismic vulnerability level of each district (and then of the great part of the municipality). With this aim, a comparison between the average values of PGAs obtained from the curves (i.e., PGA at CDF=50%) with the a g provided by the Italian code was performed. It can be noted that for a CDF=50% (at ULS) the PGAs ranges into the interval 0.55g (district 1) to 0.12g (district 4), while the expected a g referred to a mean response spectrum (at ULS) is equal to 0.178 g . The districts 1 and 3 are the most vulnerable because comprise the major number of buildings belonging to the typology URM-1 and URM-2 (that under seismic actions are the most vulnerable). On the contrary, districts which include several RC buildings are less vulnerable. Note that in this application the classes RC-1 and 2 have been grouped in a single class because have comparable structural and typological characteristics, while buildings of class RC-3 and 4 are not present in Saviano. By looking at the fragility curves indicated in Fig. 2, a damage scenario con be also predicted. In fact, the results shown that for the expected earthquakes (i.e., a g =0.178 g ) almost the Fig. 2 - a) Identification of the urban districts for Saviano municipality, b) District Fragility Curves GRAFICO DA SOSTIUIRE 0,0 0,2 0,4 0,6 0,8 1,0 0 0,05 0,1 0,15 0,2 0,25 0,3 CDF PGA/g urban dist. 1 urban dist. 2 urban dist. 3 urban dist. 4 urban dist. 5 urban dist. 6 urban dist. 7 expected ag a g =0,178g a) b)