GNGTS 2013 - Atti del 32° Convegno Nazionale

In order to obtain a risk scenario it is required to create a correlation between the Building Typology, and hence vulnerability class, and the age of buildings. For masonry building this result can be obtained using a statistical study of a sample of about 50,000 dwellings after the 1980 Irpinia earthquake (Di Pasquale et al. , 2005), where the percentage of building for each vulnerability class (the MSK macroseismic scale (Medvedev, 1977)) and age of construction are reported. In Tab. 1 a conversion table between the Building Typology used and vulnerability class according to (Di Pasquale et al. , 2005) is reported and hence the percentages of masonry buildings dating back to a specified age of construction and belonging to a particular Vulnerability class (Tab. 2). Afterwards it is possible to obtain a vulnerability curve representative of a specified Vulnerability class considering equal probability of belonging of the Building Typologies that make up that Vulnerability class. Tab. 1 – Vulnerability classes vs. horizontal and vertical structural elements (Modified from: (Di Pasquale et al. , 2005)) Horizontal structure Building types Rubble stone Simple stone Unreinforced Masonry Vaults M1_v (A) M3_v (A) M5_v (A) Wood slabs M1_w (A) M3_w (A) M5_w (B) Composite steel and masonry slabs - M3_sm (B) M5_sm (C) Reinforced concrete slabs - - M6 (C) Tab. 2 – Vulnerability classes vs. age for masonry buildings (Modified from: (Di Pasquale et al. , 2005)) Age Vulnerability class A B C1 < 1919 0.74 0.23 0.03 1919-45 0.52 0.40 0.08 1946-60 0.25 0.47 0.28 1961-71 0.04 0.31 0.65 1972-91 0.02 0.19 0.79 At this point the behavior of a masonry building dating back to a generic age of construction is evaluated considering the percentages of belonging to each Vulnerability class as the probability that the building belongs to that class, and hence as the probability that the building belongs to the Building Typologies that compose that class. As regards R.C. buildings are considered all constituted of Reinforced Concrete Moment Frame. In addition R.C. buildings falling in seismic zone has been considered to belong to a low ductility class, as Italian technical standards prior to OPCM 3274 (20/3/2003) were not able to provide a high degree of ductility to the structures, as lacking of requirements relating to 54 GNGTS 2013 S essione 2.1