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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building sample compared to the 1.034 interventions of 2021, enables to strengthen the accuracy of statistical analyses and improves the reliability of some relationships previously found, particularly for reinforced concrete, passed from 63 to 111 items. The analyses of the upgraded dataset show that the number of reinforced concrete and masonry buildings is approximately the same, but higher than the number of buildings with mixed, steel, or other structural types.The granted interventions were mainly carried out in City halls, school buildings, and hospitals. The building volume, on average, is approximately the same for the three structural types: 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. As concerns the pre- intervention safety indices (α SLVante ), the statistical analyses show lower α SLVante for reinforced concrete buildings than for masonry buildings and buildings with mixed, steel, or other structural types. The results obtained in terms of unitary costs (€/m 3 ) outline average unitary costs equal to 61€/m 3 for local strengthening, 131€/m 3 for seismic upgrading, and 207€/m 3 for demolition and reconstruction. On average, the unitary cost is the same for the three structural types, but lower, for the first two interventions, than the conventional cost assumed as the maximum grantable cost. To date, 510 interventions have been concluded, 61 of which relevant to local strengthening, 426 to seismic upgrading, and 23 to demolitions and reconstructions. For a subset of 353 seismic upgrading interventions, the increase in seismic safety and the unitary marginal cost (unitary cost to attain a 1% increase in the building safety index) have been analyzed. Reinforced concrete buildings show higher benefits since associated with greater Δα SLV increases, compared to the other two structural types. On average, marginal costs are lower for reinforced concrete (2.1 €/m 3 /%) than for masonry buildings (2.7 €/m 3 /%). This behavior can be explained by the fact that, typically, masonry structures show several complexities in behavior requiring specific structural interventions. While observing the variation of marginal costs against the safety increase (Δα SLV ), one can note that by increasing the Δα SLV , marginal costs tend to decrease for the three structural types according to an exponential trend, although sharper for reinforced concrete buildings. This can be attributed to the enlargement of the dataset of r.c. buildings, determining higher regression factors and more reliable equations compared to those obtained in 2021 by the authors. This is confirmed by an increase in R 2 values, which rise from 0.2 to 0.43. A similar adjustment can be expected for masonry and mixed (steel and other) structures when more data will become available. The formulations MC/ Δα SLV , calibrated for the three structural types, can be used according to the method defined by Dolce et al 2021, to decide the best risk mitigation strategy for a given portfolio of buildings, based on the economic resources available and of the safety index to be attained. The availability of further data in the future will allow to further refine the correlation proposed in this paper. 7. References Borzi B., Onida M., Faravelli M. et al. (2021) IRMA platform for the calculation of damages and risks of Italian residential buildings. Bull Earthquake Eng 19, 3033–3055. https://doi.org/10.1007/s10518-020-00924-x Di Ludovico M, Prota A, Moroni C, Manfredi G, Dolce M (2017a) Reconstruction process of damaged residential buildings outside historical centres after the L’Aquila earthquake: part I— “light damage” reconstruction. Bull Earthq Eng 15(2):667–692 Di Ludovico M., Prota A., Moroni C., Manfredi G., Dolce M. (2017b) Reconstruction process of damaged residential buildings outside historical centres after the L’Aquila earthquake-part II: “heavy damage” reconstruction. Bull Earthq Eng 15(2):693–729 Di Ludovico et al., (2022) Di Ludovico M., De Martino G., Prota A., Manfredi G., Dolce M., (2022), “Relationships between empirical damage and direct/indirect costs for the assessment of seismic loss scenarios”, Bulletin of Earthquake Engineering, 20, 229-254, DOI: 10.1007/s10518-021-01235-5 Dolce M. (2009). Mitigation of Seismic Risk in Italy Following the 2002 S. Giuliano Earthquake. WCCEECCE-TCCE Joint Conference Earthquake & Tsunami. Istanbul. Keynote lecture. Dolce M. (2012). The Italian national seismic prevention program. In: Proceedings of 15th world conference on earthquake engineering. September 24–28, Lisbon. Dolce M., Speranza E., De Martino G., Conte C., Giordano F. (2021) The implementation of the Italian National Seismic Prevention Plan: A focus on the seismic upgrading of critical buildings. International Journal of Disaster Risk Reduction 62. DOI: 10.1016/j.ijdrr.2021.102391 Italian Civil Protection Department (2018) National Risk Assessment 2018. Overview of the potential major disasters in Italy. Updated December 2018 Piano Nazionale per la prevenzione del rischio sismico, https://rischi.protezionecivile.gov.it/it/sismico/attivita/piano-nazionale-la-prevenzione-del rischio-sismico