PSI - Issue 44

A. Sandoli et al. / Procedia Structural Integrity 44 (2023) 1332–1339 / Structural Integrity Procedia 00 (2022) 000 – 000

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Thanks to a collection of historical photos, documents and interviews with local technicians, building inventory and damage scenarios occurred in the aftermath of 1980 have been reconstructed. Similarly, through in-situ inspections and interviews, damage scenario relative to the current urban configuration has been predicted. Balvano represented an interesting case study for the paper purposes because it allowed: ( i ) to validate the effectiveness of the methodology by comparing the predicted damage scenario with the occurred one in 1980, based on a consistent number of damaged buildings; ( ii ) to assess the seismic vulnerability in the actual configuration of the towns, highlighting the role of first seismic prescriptions released by the Italian Government at the middle of 1970s and of that specifically introduced for the reconstruction process of the zones hit by 1980 earthquakes. In addition, the proposed methodology has been integrated with a simplified approach for monetary losses estimation and with disaggregation analyses of the hazard aimed at defining multiple seismic scenarios. 2. Buildings inventory and urban compartments Urban compartments have been defined as a function of the urban development of Balvano that occurred in the aftermath of 1980 Irpinia- Basilicata earthquake (for the sake of simplicity, named with Irpinia earthquake in the following). In Fig. 2a, a map of Balvano before 1980 provided by local technicians is represented: during the post earthquake reconstruction process, the historical core of Balvano, identified with the compartment C_02 (Fig. 2a), was never reconstructed due to a significant number of damaged and collapsed buildings. Contrariwise, the zone indicated with compartment C_01 was subjected to an intense reconstruction process, where about 80% of the buildings were realized ex novo (with RC structures). Thus, for the case pre-1980 two compartments have been defined, namely C_01 and C_02; while, for the case post-1980 a single compartment C_01 (almost coincident with that pre-1980) has been identified (Fig. 2b). Building inventory has been defined by adopting the building classes proposed in Sandoli et al. 2021 for URM buildings and in Sandoli and Calderoni 2018 for the RC ones, which are representative for the Italian building stock. The detailed description of the characteristic of each building class is beyond the scope of the paper (see the reference papers), then the main characteristics of the building classes recognized in Balvano have been recalled in the following only: a) URM-1 are masonry buildings, having floors made with wooden or iron steel beams simply supported to masonry walls or with masonry vaults; they are not provided with anti-seismic devices or details devoted to inhibit out-of-plane failure mechanisms of the façade walls; b) URM-2 are masonry buildings constructed in the same age and with the same structural features of the URM-1 but, as a consequence of earthquakes damaging, they have been subjected to diffused local interventions aimed at preventing out-of-plane mechanisms; c) RC-4 are reinforced concrete buildings designed according to first seismic prescriptions released by codes or specific guidelines for the zone hit by earthquake (Law n. 64 2 February 1974; 1975 Ministerial Decree n. 93, Law n. 219 14 May 1981). As main contents, these codes categorized the national territory in zones with different seismic hazards (Balvano was classified with maximum seismic intensity, with a design peak-ground acceleration a g >0.25 g ), introducing the needs to consider horizontal seismic actions to design new buildings and the possibility of performing linear static or dynamic analyses. Nevertheless, no seismic details devoted to obtaining ductile and dissipative structures were still provided.

a)

b)

C_01

Fig. 2. (a) Urban compartments pre-1980; (b) Urban compartment post-1980