PSI - Issue 44

R. Siano et al. / Procedia Structural Integrity 44 (2023) 1038–1044 R. Siano, A. Fatnassi, F. V. De Maio, P. Basso, M. Cademartori / Structural Integrity Procedia 00 (2022) 000–000

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 geometry of the structures: this is known thanks to the execution of detailed geometric surveys conducted on the entire building.  construction details.  mechanical properties of the structural materials. The definition of the mechanical properties of the materials was supported by exhaustive in situ surveys (LC3). 4. Seismic hazard One aspect that has received particular attention is given by the seismic site effects corresponding to the amplifications and modifications that the seismic loads suffer once reached the surface as a function of the geotechnical characteristics of each site. A seismic framework of the area is presented where the tectonic aspects and some elements of the historical seismicity of the area are described. The characteristic magnitudes of the earthquakes were also identified, depending on the return period and therefore on the limit state of interest. A local seismic response analysis was performed to determine the design spectra with reference to SLO, SLD and SLV. This analysis was carried out by propagating a set of accelerograms through a 1D numerical model of the column of soil present at the site. A non-linear modeling of the behavior of the soil was carried out, considering a hyperbolic model calibrated on the decay curves of the stiffness and damping of the soils crossed, selected from literature data in the absence of direct measurements. The analyses were repeated using two geotechnical models with two different shear wave velocity profiles, respectively representative of the west-southwest area and the north-east area of the area . The results show that for low return periods, associated with SLD and SLO, the response on the surface presents an amplification of the seismic motion with respect to the spectrum on rock, while for SLV the motion on rock is reduced for low response periods (less than 0.3s) and amplified for longer response periods (although to a lesser extent than the other limit states). The horizontal design spectra were finally defined by applying the regularization procedure described in Circolare Ministeriale no. 55 . The figures below (Fig. 1) report the results provided by the local seismic response analysis in terms of seismic design spectra for SLV and SLD.

Fig. 1. Seismic Design Spectrum define in the area for SLV and SLD

5. Main results of the vulnerability analysis 5.1. Retrofit solutions

Once performed the seismic assessment of the buildings sample, different conceptual retrofit scenarios were defined and compared starting from the observation of the specific vulnerability defined for each building. The