PSI - Issue 44

Gaetano Della Corte et al. / Procedia Structural Integrity 44 (2023) 472–479 Cantisani, Della Corte / Structural Integrity Procedia 00 (2022) 000–000

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global system stiffness while minimizing the moment demand to the connections between the link and the existing RC frame members. However, short links might develop inelastic shear forces largely exceeding the yielding resistance, due to cyclic steel strain hardening effects and depending also on the link relative length and boundary conditions (Barecchia et al. (2006b), Della Corte et al. (2007), Della Corte et al. (2013), Manganiello et al. (2021)). This paper summarizes the main seismic response issues with relevant modelling options, while focusing on the following specific aspects: (i) out-of-plan stability, (ii) link plastic overstrength, (iii) ductility. An existing school building in Italy is taken as a case study (ReLUIS (2021)) to show a realistic application and relevant numerical results. 2. The Y-bracing system The considered system comprises two diagonal braces and a vertical shear link, which is used as the yielding element, as for ordinary eccentric bracing systems. The additional steel elements are connected to the existing building by means of two or more connection types. Fig. 1(a) shows a conceptual sketch of the considered system, while Fig. 1(b) shows a plan view of the case study building, with location of the eccentric braces. The structure is an existing school building which was already analyzed in Cantisani et al. (2021).

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Fig. 1. Case study structure: (a) conceptual sketch of the retrofitting system; (b) building plan; (c) connections between the link, the RC beam and the diagonal members; (d) connection between the diagonal member and the RC frame.