PSI - Issue 44

Fabrizio Comodini et al. / Procedia Structural Integrity 44 (2023) 1076–1083 Author name / Structural Integrity Procedia 00 (2022) 000–000

1083

8

Table 3 Results of seismic assessment Collapse mechanisms

Seismic Capacity (C)

Seismic Demand (D)

Ratio C/D

ξ E

ag/g

Return Time

ag/g

Return Time

Shear collapse Flexion collapse

0,140 0,153 0,227 0,227

176 227 712 712

0,227 0,227 0,227 0,227

712 712 712 712

0,62 0,67 > 1,0 > 1,0

Joint collapse

Foundations collapse

6. Conclusions This paper has presented the results of a seismic improvement intervention that applied the exoskeleton technique to a real case study. In particular, a new device was used to couple the exoskeletons to the existing structure. The chosen device allows the transfer of seismic plane forces between the two coupled structures without generating critical axial stresses for the existing columns. The shear connector element has an elastic/plastic behavior with a modular elastic limit as a function of its geometric values. The connector represents the sacrificial element of the device overall and can be replaced after its plasticization. The design of the exoskeletons studied in this paper was based on two fundamental principles: adequate stiffness, so that the higher rate of the expected seismic demand is transferred to them, and the ability to overstrength against the expected seismic action. The results of the numerical analysis demonstrate the effectiveness of the exoskeletons as they produce the expected capacity. Increase. The use of this technique, even if accompanied by other localized interventions, permits the continued use of the structure during the execution of the works. These techniques have consequences and benefits at various levels and promote the upcycling of the building structure; improve its seismic resistance and resilience; reduce the environmental impacts associated with seismic risk; increase the real estate value; protect economic investments in the long term; reduce renovation costs following the increase in resilience; allow architectural, energy and structural renovations to coexist on a single site. 7. Bibliografia Comodini Fabrizio; D'Ambrisi Angelo; Mezzi Marco (2021), Nodal dissipative devices for seismic protection of precast rc structures, COMPDYN 2021 8th International Conference. Conference proceedings - Volume I DOI:10.7712/120121.8824.19434. pp.4772-4781. Eurostat, (2001), “Owner-Occupied Dwellings by Type and Year of Construction of the Building” Eurostat, Luxembourg. Fajfar, P., (1999), “Capacity Spectrum Method Based on Inelastic Demand”, Spectra Earthquake Engng. Struct. Dyn., 28, 979-993. Federal Emergency Management Agency (FEMA), (2006), “Techniques for the Seismic Rehabilitation of Existing Buildings”, FEMA 547/2006. Feroldi, F., Marini, A., Belleri, A., Passoni, C., Riva, P., Preti, M., Giuriani, E., Plizzari, G. (2014). Sustainable seismic retrofit of modern RC buildings through an integrated structural, energetic and architectural approach adopting external engineered double skin façades”, Progettazione Sismica, 5 (2), 1-15 (in Italian). Foraboschi, P., Giani, H., (2018), “Esoscheletri: Miglioramento sismico e rigenerazione architettonica (Seconda Parte)”, Structural, 215, 1-19. Di Lorenzo G., Colacurcio E., Di Filippo A., Formisano A., Massimilla A., Landolfo R., (2020). State-of-the-art on steel exoskeletons for seismic retrofit of existing rc buildings, International Journal of earthquake Engineering , Vol.n.1 XXXVII year . Reggio A., Restuccia L., Ferro G.A., (2018). Feasibility and effectiveness of exoskeleton structures for seismic protection. Procedia Structural Integrity ,Volume 9, Pages 303-310. NTC2018, Norme tecniche per le costruzioni, D.M. 16 Gennaio 2018, Italy