PSI - Issue 44

Elena Speranza et al. / Procedia Structural Integrity 44 (2023) 1784–1791 Elena Speranza et al../ Structural Integrity Procedia 00 (2022) 000–000

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(a) Reinforced concrete

(b) Masonry

(c) Mixed, steel or other

Fig. 2. Distribution of interventions and relevant cumulative percentages as a function of intended use for reinforced concrete (a), masonry (b) and mixed, steel or other structure (c).

Fig. 3 shows the distribution of the volumes for buildings with reinforced concrete structures (a), masonry structures (b), and mixed, steel, or other structural types (c). The graphs show that the volume is quite similar between reinforced concrete and masonry buildings, while it is higher for buildings with mixed, steel, or other structural types. On average, the volume is equal to 6,697 m 3 for reinforced concrete buildings, 6,252 m 3 for masonry buildings, and 6,170 m 3 for buildings with mixed, steel, or other structural types.

(a) Reinforced concrete

(b) Masonry

(c) Mixed, steel or other

Fig. 3. Distribution of interventions and relevant cumulative percentages as a function of volume for reinforced concrete (a), masonry (b), and mixed, steel or other structure (c).

The seismic structural safety of the building in the original configuration is used to check the structural capacity before the intervention. It is conveyed through a seismic safety index , α, representative of the percentage capacity of the building to resist the seismic actions required for the design of a new building at the ultimate limit state, SLV (Ministerial Decree 2008; Circular n. 617 2009). It is expressed as a ratio between demand and capacity peak ground acceleration. The seismic safety indices pre-interventions , α SLVante , is available for 1,121 buildings of the sample. The distribution for the three structural types as a function of α SLVante indices, grouped into 8 intervals with a step of 10%, ranging from 0 to 80%, is reported in Fig. 4a, Fig. 4b, and Fig. 4c respectively. As concerns reinforced concrete (505 buildings), in 56% of the cases the seismic safety indices α SLVante range between 0 and 20%, while for 26% of the items α SLVante is between 20% and 30% (i.e. 82% of buildings of the sample was capable to meet with at most 40% of the current seismic code action requirements), outlining the very high vulnerability of the stock. As concerns masonry buildings (465) and buildings with mixed, steel, or other structural types (164), 72% and 77% respectively were capable to resist at most 30% of the current seismic code action requirements, with similar considerations to those drawn for reinforced concrete buildings. In other words, these distributions confirm the prioritization criteria carried out by Regions in intervention scheduling.