GNGTS 2019 - Atti del 38° Convegno Nazionale

GNGTS 2019 S essione 2.2 419 with f 1 =0.05 [ g ] and f 2 =1.66, resulting very similar to Margottini et al. (1992) ( f 1 =0.043 [ g ] and f 2 =1.66). The lognormal fragility curve parameters (median value and dispersion) are then given analytically by: where the dispersion is given by two contributions: • β 1 = ( a k f 2 + b k ) V + ( c k f 2 + d k ) is implicit in the EMS 98 macroseismic model and has been obtained by fitting the analytical curves through the coefficients in Tab. 2; Table 2 - Coefficients for the evaluation of the dispersion β 1 . D1 D2 D3 - D4 D5 a k 0.625 0.75 0.719 0.75 b k -0.5075 -0.675 -0.523 -0.535 c k 0.281 0.219 0.25 0.3125 d k 0.0131 -0.1031 -0.245 -0.309 • β 2 = 0.36 – 0.06 k is related to the variability obtained by fitting damage data observed after different earthquakes (in particular Irpinia 1980 and L’Aquila 2009), and might be eliminated if a regional vulnerability should be introduced in the future. The parameters of the fragility curves for the EMS 98 vulnerability classes are given in Tab. 3. Table 3 - Median (PGA) and dispersion ( β ) of the lognormal fragility curves for vulnerability classes. Vulnerability     D1      D2      D3      D4      D5 class PGA [g] β [-] PGA [g] β [-] PGA [g] β [-] PGA [g] β [-] PGA [g] β [-] A 0.064 1.00 0.161 0.81 0.309 0.79 0.594 0.78 1.491 0.85 B 0.104 0.92 0.232 0.72 0.409 0.69 0.722 0.68 1.605 0.74 C1 0.180 0.83 0.350 0.63 0.560 0.57 0.898 0.56 1.744 0.61 D 0.275 0.76 0.481 0.55 0.716 0.49 1.064 0.47 1.860 0.51 The vulnerability index V was obtained for the masonry buildings subtypes, which may be defined by ISTAT data by considering age and storey class (Low 1-2; Medium 3-5; High >5). Therefore, the percentage of buildings in each class was identified (Tab. 4), in order to reproduce the observed vulnerability. Table 4 - Composition of the masonry building stock in terms of percentages of vulnerability classes. Vulnerability Pre-1919 1919-45 1946-61 1962-81 Post 1981 class L M H L M H L M H L M H L M H A 80% 60% 100% 25% 60% B 20% 40% 75% 90% 40% 50% 70% 85% 20% 45% C1 10% 50% 30% 15% 70% 80% 55% 40% 70% D 30% 100% 60% 30%