PSI - Issue 64

Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2023) 000 – 000

www.elsevier.com/locate/procedia

ScienceDirect

Procedia Structural Integrity 64 (2024) 885–892

SMAR 2024 – 7th International Conference on Smart Monitoring, Assessment and Rehabilitation of Civil Structures Seismic retrofitting of an existing hospital with external steel brace Maximilian Fehr a , Michael Baur a, *, Giovacchino Genesio b a Lucerne School of Engineering and Architecture, Lucerne, Switzerland b Hilti Entwicklungsgesellschaft mbH, Kaufering, Germany Abstract Earthquakes may cause serious damage to buildings and result in heavy losses to society, therefore, it is necessary to enhance the seismic capacity of existing buildings via structural retrofitting. The traditional retrofitting approaches are based on the component-level, but their improvement effect for the overall structure is not obvious. Until now, the seismic retrofitting technology can be generally divided into three types. The first is strength-improving type, the second is ductility-improving type, and the third is seismic dissipation/isolation type. Commonly a combination of these three types is used in retrofitting solutions. Most of them are focused on member based or component-level improvements of strength and/or ductility applied to poorly reinforced concrete walls or columns and masonry walls. Meanwhile, the weak element of the existing structure can be strengthened by external sub-structures as steel frames to make the overall structural capacity or stiffness more uniform. In addition, because the construction is an external operation, it can achieve non-disturbing retrofitting without affecting the normal use of the inner structure, which is of great practical significance and social benefits for lifeline projects such as schools and hospitals that cannot be interrupted. In the present case study, the efficiency of a seismic retrofitting with external steel frame of the university hospital Zurich (USZ) will be discussed. The original 3-story reinforced concrete building with a rectangular floor plan of 44m x 24m was built in 1966. Subsequently, in 1970, the building was extended by 4 floors with a composite steel structure. On the roof floor there is a helipad for emergencies. The stiffening steel structure was connected to the building with post-installed anchors. The first results of a response spectrum analysis showed major deficiencies in terms of horizontal and torsional stiffness, so that a strengthening measure became necessary. The results were verified by means of a push-over analysis, which showed that the measure applied was very effective. Finally, the structural design and the connection details to the existing concrete structure are shown.

* Corresponding author. Tel.: +41 41 349 34 33. E-mail address: michael.baur@hslu.ch

2452-3216 © 2024 Maximilian FEHR, Michael BAUR, Giovacchino GENESIO. 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 SMAR 2024 Organizers

2452-3216 © 2024 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 SMAR 2024 Organizers 10.1016/j.prostr.2024.09.363