PSI - Issue 44

Sergio Ruggieri et al. / Procedia Structural Integrity 44 (2023) 1964–1971 Sergio Ruggieri et al./ Structural Integrity Procedia 00 (2022) 000–000

1970

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and a dispersion of 0.27 for brittle mechanisms, a median of 0.352 and a dispersion of 0.36 for ductile mechanisms. For B2, a median of 0.215, a dispersion of 0.30 for brittle mechanisms, a median of 0.483, and a dispersion of 0.396 for ductile mechanisms have been obtained.

Fig. 3. Fragility curves for B1 and B2, accounting for brittle and ductile mechanisms.

A fuse of fragility curves has been obtained for both investigated failure mechanisms, which cover a probable range in which the vulnerability of buildings can be allocated. As expected, B1 is more vulnerable than B2 under seismic actions, since the design does not account for seismic details. Anyway, fragility curves for ductile mechanisms are shifted to the right respect to brittle mechanisms. On the other hand, the higher number of storeys and the presence of higher ground floor in B2 does not allow a significant improvement of B2 fragility than B1. 6. Conclusions and further developments The paper presents a procedure to investigate seismic vulnerability of existing buildings starting from a photo, combining two automated processes: (i) definition of the main structural features of the building pictured in a photograph through VULMA framework; (ii) simulated design, modelling and analysis starting from the input data previously extracted and defining unknown parameters (e.g., geometrical and mechanical) accounting for a certain variability. The procedure has been specified with reference to the Italian context and has been applied on two case study buildings in Southern Italy, Puglia, for which photographs are available. By applying all the phases of the proposed procedure, a fuse of fragility curves has been obtained for the investigated limit states and failure mechanisms: their mean fragility curve indicates the seismic vulnerability of the buildings under study. The results can be used for providing qualitative indications about the building stock of a specific area, on which photographs are available. The main advantages of the procedure are: (a) part of the structural features are automatically defined by using VULMA starting from a photo and, using few additional data, a mechanical modelling can be processed; (b) properly assuming unknown parameters, an automatic procedure generates the models representing ideal buildings, performs analyses to predict the structural behavior of the building under study considering the uncertainties; (c) as a final result, a range of fragility curves is obtained, which describes the vulnerability of the building under study and can be investigated in a probabilistic way (e.g., mean and fractiles). As further development of the procedure, the number of curves for estimating fragility of the examined buildings can be increased, for example by treating the unknown parameters as random variables or by opting for a denser discretization of the employed parameters. In addition, the procedure can be better automatized and extended to other types of buildings, such as masonry or steel ones, in order to provide a tool that can be widely appliable for risk mitigation plans. Acknowledgements Authors acknowledge the FABRE Consortium for the financial support, within the agreement named “ Supporto tecnico-scientifico per lo sviluppo della metodologia per il censimento, ispezioni iniziali e individuazione delle Classi di Attenzione di un campione di ponti e viadotti gestiti da Anas Spa; prioritarizzazione delle operazioni di valutazione di livello 4; verifica della qualità e di omogeneità dei risultati ”.