PSI - Issue 44

Alessandra Gubana et al. / Procedia Structural Integrity 44 (2023) 512–519 A. Gubana and A. Mazelli / Structural Integrity Procedia 00 (2022) 000–000

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Fragility curves were evaluated by means of formulation (1) for each direction and for both the selected IMs. Fig. shows the FCs for each DL of Table 1. Fig. illustrates the comparison between the FCs for each direction and for DL1 (grey) and DL4-5 (black).

Fig. 7. Fragility curves for the bidirectional case and for PGA (a) and S a (T 1 ).

Fig. 8. Comparison between FCs in terms of PGA (a) and S a (T 1 ) (b) for all analysis directions (note: -45° behaviour is very similar to the +45° behaviour, and the graph has been removed to improve clarity).

In this specific case study, the loss of stiffness in the transversal direction Y, due to the shear collapse of the RC cores, led to double the fundamental period and consequently to a different position in the pseudo acceleration response spectrum. In this case, choosing S a (T 1 ) as IM led to the Y behaviour being the strongest one in opposition to pushover

and IDA results. 6. Conclusions In this work, a case study of fragility analyses for an RC hospital building was presented. Before these analyses elastic modal and pushover analyses were performed.

As expectable, in all the different approaches, the results obtained showed a completely different behaviour between the two directions, with the transverse one as the weakest, due to the high shear fragility of the walls. Nonetheless, the structure has a ductile behaviour in the longitudinal direction. Furthermore, the evaluation of the fragility curves highlighted that the choice of the intensity measure still requires a deeper evaluation. The variation of the first mode