GNGTS 2021 - Atti del 39° Convegno Nazionale

GNGTS 2021 S essione 2.2 274 empirical formulation given by Lagomarsino and Giovinazzi (2006), starting from the vulnerability index achieved from the proposed vulnerability form (Chieffo and Formisano, 2020). Differently, by increasing the distance up to a maximum of 30 km and by leaving unaltered the magnitude, the seismic effects are reduced and damage level D1 (moderate damage) is expected in 69 % of the cases. Finally, the empirical fragility curves, have been derived through the Maximum Likelihood Estimation Method (MLE) applied to PGA values. In particular, in order to quantify the expected damage level associated to different PGA values for each building, the empirical formulation proposed by Gaugenti and Petrini (1989) has been used to correlate the macroseismic intensity with the corresponding PGA. Thus, the worst damage scenario for Mw= 6.5 and R= 10 km has been developed. The empirically derived curves have been compared to those proposed by the literature data. It is possible to notice how for lower PGAs thresholds, the considered literature curves (Dolce et al., 2020) tend to underestimate the expected damage. In this overview, referring to the typological class C, for an expected PGA equal to 0.4, the probability of exceeding the damage threshold D3 is equal to 70%, while according to what is proposed by Dolce et al. it is 20%, with an expected underestimation of 71%. This discrepancy arises from the fact that the considered derivation procedure is based on a different lognormal evaluation procedure, in which the mean and standard deviation parameters have been calibrated on a statistical basis for a larger number of buildings. The summary of the above-mentioned simulation is presented in Fig. 2. Conclusion The research analysed the seismic vulnerability of the historical centre of Latronico by using a proper parametric-deterministic approach. The main study outcomes are summarized below: • From the typological-structural characterization of the urban sector examined, the prevailing masonry class was the MUR1 (rough-stone), which represented 75% of the building asset. The analysis results showed a medium vulnerability (0.4<VI<0.6) of the analysed sector. Fig. 2: Calculated DPMs and fragility curves.