PSI - Issue 44

Brandonisio Giuseppe et al. / Procedia Structural Integrity 44 (2023) 1292–1299 Giuseppe Brandonisio et al. / Structural Integrity Procedia 00 (2022) 000–000

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buildings are separated by tight joints: the reduced clearance between adjacent portions is inappropriate to avoid pounding damages due to earthquake shaking.

Fig. 1. Overhead view of High School “R. Caccioppoli”, with location of the three jointed buildings

3. Seismic vulnerability at the current state Seismic assessment of the whole complex at the current state has been evaluated through push-over analysis on 3D models of these buildings. For each orthogonal direction, two different force distribution have been considered: one is proportional to the modal shapes, the other to the masses. The analyses have been performed by using the software CDS-WIN (Computer Design of Structure s, S.T.S. S.r.l., 2021). Fig. 2 shows the 3-D CDS finite element models of the buildings 1, 2, and 3. By way of example of the pushover analysis, the left side of Fig.3 shows the collapse mechanism for the Building 3 obtained through the pushover in X+-direction; on the right side it is visible the corresponding evaluation of seismic vulnerability assessment in ADRS plane (Fajfar, 1999) (Fajfar, 2000).

Fig. 2. The 3-D CDS finite element models of the buildings 1, 2, and 3. Table 1 shows the results of pushover analyses at the LLS (Life Limit State) for Buildings 1, 2, and 3 in terms of Seismic vulnerability index ( z E ), defined by the ratio between the maximum peak ground acceleration that building can withstand (PGA C ) and the demand peak ground acceleration (PGA D =0.191g at the return period T R =712 years).In particular, for “Building 1” the lowest value of seismic vulnerability index, z E = 0.0063, is related to modal force distributions in longitudinal direction; in this case, the first collapsing element is the shear wall of the inner staircase, undergoing shear failure. For “Building 2” the lowest value of seismic vulnerability index, z E = 0.11, is due to modal