PSI - Issue 44

Giuseppe Brandonisio et al. / Procedia Structural Integrity 44 (2023) 1316–1323 Giuseppe Brandonisio et al. / Structural Integrity Procedia 00 (2022) 000–000

1323

8

building height, characterized by a “floating plane” that connects a wide upper and more deformable steel portion to a lower stiffer R.C. part. In this case, a hybrid approach for seismic retrofitting is proposed, applying an isolation system to a previously strengthened and stiffened structure. In particular, to regularize the stiffness distribution in the plan, due to the asymmetrical arrangement of shear walls, other two R.C. cores can be introduced, while the existing ones have to be strengthened. At the upper levels, characterized by very deformable steel frames, partially braced, the shear walls are the only elements having a certain horizontal stiffness to counteract seismic actions. Also, the existing SAP-type slabs have to be consolidated, creating a rigid diaphragm at each floor level to improve the seismic behavior of the overall structure. In this case, the isolation system is introduced below the floating plane, where the shear walls have to be cut to ensure the functioning of the isolation system. The use of BIS gives the possibility to elongate the vibration period of 5.42-times, reducing the seismic forces of 76% compared to the AS-IS configuration. This hybrid strategy is able to improve seismic response of such building greatly. Following an integrated design approach, this not-intrusive solution remains respectful of the original layout, proposing structural interventions easy to be put in practice, without interfering with the current functions. Acknowledgements The support provided by consortium ReLUIS is acknowledged. The research activities are related to the topics of WP5 “ Interventi di rapida esecuzione a basso impatto e integrati ” e and W15 “ Isolamento e dissipazione ”, included in the three-years project DPC-ReLUIS 2019-2021. Thanks to Eng. Antonio L’Arciprete and Eng. Feola Raffaele for their precious contributions in the numerical analyses. References Brandonisio, G., Ponzo. F., Mele, E., De Luca, A., (2017). “Prove sperimentali di isolatori elastomerici: influenza del carico verticale V e del fattore di forma secondario S2”. Atti del XVII Convegno ANIDIS, Associazione Nazionale Italiana di Ingegneria Sismica. Brandonisio, G., Guidi, L.G., De Luca, A. (2019). “Stability evaluation for rubber bearings: code requirements and comparison with experimental results”, Atti del XVIII Convegno ANIDIS, Associazione Nazionale Italiana di Ingegneria Sismica. CSI-Italia Srl. (2021). SAP2000 vers. 23 – Manuale. De Luca, A., Mele, E., Molina, J., Verzeletti, G., and Pinto, A. V. (2001). Base isolation for retrofitting historic buildings: evaluation of seismic performance through experimental investigation. Earthquake Eng. Struct. Dynam. 30, 1125–1145. doi: 10.1002/eqe.54. De Luca A, Brandonisio G, Luongo S, De Martino A, Mautone G, De Stefano G, D'Onofrio G. Una soluzione tutta gomma per l ’ isolamento di una struttura esistente in c.a.: le “ strutture di trasferimento ” . Atti del XVI Convegno ANIDIS, Associazione Nazionale Italiana di Ingegneria Sismica; 2015. De Luca, A. and Guidi, L.G. (2019). “State of Art on the Worldwide Evolution of Base Isolation Design”. Soil Dynamics and Earthquake Engineering, 125 (2019) 105722. https://doi.org/10.1016/j.soildyn.2019.105722. De Luca, A. and Guidi L.G. (2020). “Base isolation issues in Italy: Integrated Architectural and Structural Design”. Soil Dynamics and Earthquake Engineering, 130 (2020) 105912. https://doi.org/10.1016/j.soildyn.2019.105912. De Luca, A., Guidi, L.G., Brandonisio, G., Ponzo, F.C., (2022). “Horizontal capacity of base isolation rubber devices under large vertical design stress, valued through full-scale tests”. Soil Dynamics and Earthquake Engineering. Volume 159, August 2022, 107264. https://doi.org/10.1016/j.soildyn.2022.107264. Miyazaki M. The Next generation of seismic isolation. Going beyond seismic design dominated by earthquakes. J Disaster Res 2008;3(6):479 – 502. Ministero delle Infrastrutture (Italy), Aggiornamento delle norme tecniche per le Costruzioni. D.M. 17/01/2018. Gazzetta Ufficiale No.42 del 20/02/2018. S.T.S. S.r.l., (2021) Manuale d’uso. CDSWin + CDMaWin Strutture in c.a., acciaio, legno e muratura Youssef N, Hata O. Seismic retrofit and instrumentation of Los Angeles city Hall. SMIP05 seminar proceedings. California: Seminar on Utilization of Strong-Motion Data; 2005. p. 115–30. Walters Mason. Forell/elsesser engineers. The seismic retrofit of the Oakland city Hall. SMIP03 seminar proceedings. California: Seminar on Utilization of Strong- Motion Data; 2003. p. 149–64.