PSI - Issue 64

Sabatino Di Benedetto et al. / Procedia Structural Integrity 64 (2024) 983–990 S. Di Benedetto / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 3. Photos of pinned connections.

Fig. 4. Connection of the bracings to the column (at level 1).

Considering that the structure was built in 1982, all design documents are available, providing information on the geometry, structural details, and material properties of the analysed building, leading to a knowledge level of KL3 and a confidence factor of 1, as per NTC2018 and Circular No. 7 (2019). Specifically, members of the structural elevation are composed of S235 nominal steel grade, while the foundation consists of C20/25 concrete and FeB44K type bars. The composite slab at the first floor carries a weight of 2 kN/m 2 (G k1 ), with an additional 1.6 kN/m 2 contributed by the screed, false ceiling, and partition walls (G k2 ). Conversely, the roof level bears a load of 2 kN/m 2 , including components such as the steel substructure, waterproof membrane, lightweight screed, insulation panel, corrugated sheet, and false ceiling. The variable load (Q k ) at the first level is 3 kN/m 2 , while the roof snow load is 1.07 kN/m 2 . Wind load is applied to the facades based on Italian regulations and the structure's location. The facades consist of precast concrete panels with insulating cores, each weighing approximately 3.30 kN/m 2 . Considering these loads, the seismic mass of the building, defined using the G k1 +G k2 +0.6Q k combination, is approximately 2000 tons. Design spectra for DL and LS limit states were established in accordance with NTC2018 regulations for the Municipality of Avellino, assuming a nominal life of 50 years, service class III, a utilization factor of 1.5, and soil category C. As the original structure lacks specific devices for seismic energy dissipation, a behaviour factor of

q=1.5 can be adopted at the LS Limit State. 3. Assessment of the existing structure

According to the Italian code NTC2018, the seismic vulnerability of a structure can be quantified using a risk index denoted as  E , which is calculated as the ratio between the maximum seismic force that the structure can withstand, and the maximum seismic force used in designing a new construction. Typically, the term "maximum seismic force" refers to the highest design horizontal peak ground acceleration at the reference site, expressed in terms of capacity (PGA C ) and demand (PGA D ).