PSI - Issue 44

Available online at www.sciencedirect.com Structural Int grity Procedia 00 (2022) 000–000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2022) 000–000 Available online at www.sciencedirect.com ScienceDirect

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Procedia Structural Integrity 44 (2023) 1292–1299

© 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the XIX ANIDIS Conference, Seismic Engineering in Italy. A hybrid procedure for seismic retrofit of an existing R.C. structure by using base isolation system is discussed in this paper. The case study is a high school building in Naples, built at the end of 1970s, as result of a gravity-load design approach. It consists of three jointed R.C. portions, having different features in plan and elevation. In particular, “Building 1” and “Building 2” are characterized by resisting frames only in transversal direction. These ones support the actions transferred by the floors, whose load bearing elements are warped longitudinally. Both the two buildings are characterized by some R.C. shear walls, in correspondence of (internal/external) staircases. The three portions are separated by tight joints, whose width is inappropriate to avoid pounding damages due to earthquake shaking. Considering that the structure has no resisting frames in longitudinal direction, this school building has low seismic capacity longitudinally and a high lateral deformability, with a fundamental vibration period of T AS-IS =1.37s. In this case, seismic retrofit by using base isolation system has been necessary to improve its seismic response. On the other hand, the main aspects of modern capacity design approach are not complied with between dissipative and no-dissipative components. So, it is assumed that the current structural system has no ductility reserves, on local and global scale. For the seismic retrofit of the existing structure an “all rubber” base isolation system (BIS) has been assumed by using f 600 HDRBs, allowing to reach a T ISO = 4.0s. To maximize the effectiveness of BIS, the three bodies have been connected at each floor level and the upper structure has been strengthened previously, reducing to T FB =0.30s the fundamental period of the strengthened fixed base solution. The proposed hybrid solution for seismic retrofitting merges two conceptually opposite design strategies, opting for BIS applied to an existing structure, stiffened ad hoc by using shear walls. © 2022 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license ( https://creativecommons.org/licenses/by-nc-nd/4.0 ) Peer-review under responsibility of the scientific committee of the XIX ANIDIS Conference, Seismic Engineering in Italy XIX ANIDIS Conference, Seismic Engineering in Italy Hybrid strategy for the seismic retrofitting of existing buildings through Base Isolation System Brandonisio Giuseppe a , Laura Giovanna Guidi a *, Guido Camarda a , Paola Sorrentino a , Antonello De Luca a a Dept. of Structures for Engineering and Architecture, University of Naples Federico II, via Claudio 21, 80125 Naples, Italy Abstract A hybrid procedure for seismic retrofit of an existing R.C. structure by using base isolation system is discussed in this paper. The case study is a high school building in Naples, built at the end of 1970s, as result of a gravity-load design approach. It consists of three jointed R.C. portions, having different features in plan and elevation. In particular, “Building 1” and “Building 2” are characterized by resisting frames only in transversal direction. These ones support the actions transferred by the floors, whose load bearing elements are warped longitudinally. Both the two buildings are characterized by some R.C. shear walls, in correspondence of (internal/external) staircases. The three portions are separated by tight joints, whose width is inappropriate to avoid pounding damages due to earthquake shaking. Considering that the structure has no resisting frames in longitudinal direction, this school building has low seismic capacity longitudinally and a high lateral deformability, with a fundamental vibration period of T AS-IS =1.37s. In this case, seismic retrofit by using base isolation system has been necessary to improve its seismic response. On the other hand, the main aspects of modern capacity design approach are not complied with between dissipative and no-dissipative components. So, it is assumed that the current structural system has no ductility reserves, on local and global scale. For the seismic retrofit of the existing structure an “all rubber” base isolation system (BIS) has been assumed by using f 600 HDRBs, allowing to reach a T ISO = 4.0s. To maximize the effectiveness of BIS, the three bodies have been connected at each floor level and the upper structure has been strengthened previously, reducing to T FB =0.30s the fundamental period of the strengthened fixed base solution. The proposed hybrid solution for seismic retrofitting merges two conceptually opposite design strategies, opting for BIS applied to an existing structure, stiffened ad hoc by using shear walls. © 2022 The Authors. Published by ELSEVIER B.V. open a cess article under the CC BY- C-ND license ( https://creativecommons.org/licenses/by-nc-nd/4.0 ) Peer-review under responsibility of the scientific committee of the XIX ANIDIS Conference, Seismic Engineering in Italy XIX ANIDIS Conference, Seismic Engineering in Italy Hybrid strategy for the seismic retrofitting of existing buildings through Base Isolation System Brandonisio Giuseppe a , Laura Giovanna Guidi a *, Guido Camarda a , Paola Sorrentino a , Antonello De Luca a a Dept. of Structures for Engineering and Architecture, University of Naples Federico II, via Claudio 21, 80125 Naples, Italy Abstract

* Corresponding author. E-mail address: lauragiovanna.guidi@unina.it * Corresponding author. E-mail address: lauragiovanna.guidi@unina.it

2452-3216 © 2022 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the XIX ANIDIS Conference, Seismic Engineering in Italy 2452-3216 © 2022 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the XIX ANIDIS Conference, Seismic Engineering in Italy

2452-3216 © 2023 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the XIX ANIDIS Conference, Seismic Engineering in Italy. 10.1016/j.prostr.2023.01.166