GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 2.2 GNGTS 2023 σ = ∑ −µ | ( ) 2 −2 (4) being nPGA the number of PGA considered for the evaluation of the seismic input, lnDI DSi the conditional natural logarithm of the damage indices evaluated by using the average spectra and n the number of the generated virtual buildings, - σ rtrDSi is estimated as (Lagomarsino and Cattari, 2014): σ = 1 2 · 16 − 84 ||| ||| (5) being and the mean values of the natural logarithm of the damage indices evaluated 16 84 respectively by using the spectra corresponding to the 84 th and the 16 th percentile of the selected records. Eqn. 4 provides a measure of the deviation of the i-th damage variable DI DSi from the corresponding mean value evaluated through Eqn. 2: σ mDSi represents the uncertainty due to the variability of the model, while σ rtrDSi (eqn. 5) represents the uncertainty due to the variability of the selected records. The described approach has been applied to define the fragility curves of the building populations generated on the base of the buildings’ characteristics belonging to the typologies identified in a real case study, that is the historical centre of Sora (Fig. 2), in province of Frosinone. Fig. 2. View of the historical centre of Sora. In this historical centre, investigated by the authors within the CARTIS project (DPC/ReLUIS 2019-2021), two masonry building typologies have been recognized, named respectively MUR1 and MUR2. MUR1 is characterized by buildings made of irregular masonry with rubble rough stones, with the age of construction prior to 1860 and mostly with wooden slabs. The buildings belonging to MUR2 are made of regular masonry with square stones, built between 1861 and 1945, and mainly characterized by slabs in hollow core concrete. Both the typologies are