PSI - Issue 62

D’Amato Michele et al. / Procedia Structural Integrity 62 (2024) 137–144 D’Amato M. et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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The highest H-CoA are registered in the case of Viaduct I and Viaduct II, resulting respectively Medium-High and High H-CoA. They are strongly influenced by the partial CoAs related to scouring phenomena or by the failure of downstream hydraulic structures. In particular, it should be noted that the Italian Guidelines (MTI, 2020) provides an underestimation of the current H-CoA for Viaduct I, resulting in this case Medium-High although the high criticalities observed during the in-situ inspection. While, as for the Viaduct II, the High H-CoA is principal due to local scouring caused by the flow angle impacting the bridge piers. On the opposite, as for SF-CoA and S-CoA, the highest risk is registered on the Viaduct III and Viaduct IV, reporting evident scouring phenomena on piers and abutments foundations. The defect level is the most impactful parameter for defining SF-CoA and S-CoA since it significantly affects the vulnerability class. Nevertheless, the SF CoA plays a key role for the Overall Class of Attention (O-CoA), since a High SF-CoA also implies a High O-CoA, as in the case of the Viaduct III and Viaduct IV. From the hydraulic point of view, the Viaduct III and Viaduct IV result in a Medium H-CoA. In both cases, the final hydraulic risk is influenced by a Medium-Low vulnerability class for local scouring, which does not consider the evidence of material removal around piers and abutments. Nevertheless, in these cases the drainage system failure induces a deep local scouring around piers and abutments, that is a phenomenon deserving more attention. 5. Conclusion This research is focused on defects detected on piers and abutments of four bridges located in the State Road networks of the Basilicata region, by applying the multi-criteria approach proposed by the Italian Guidelines, with particular regard to the Level 0, Level 1 and Level 2. The results obtained highlight the importance of a multi-criteria approach for better evaluating the current Overall Class of Attention (O-CoA, Level 2), including structural and hydraulic aspects as well as their combination. Among the others, significant defects have been observed for bridges where drainage system failure induces deep local scouring around piers and abutments, leading to a High SF-CoA and O-CoA, even if it does not significantly influence the H-CoA. The evidences observed in this study, although limited to only four existing bridges, provide some useful indication in order to properly evaluate the current Overall Class of Attention, and to how it is possible to quickly reduce the vulnerability (such structural, seismic and hydraulic) in a very short time limiting the use of economic resources. Firstly, it is highlighted the necessity of continuous monitoring activities with the aim to better understand processes evolution over time, that may reveal risk conditions not easily detectable with a single inspection. Moreover, visual inspections are essential not only for assessing hydraulic phenomena, especially after unexpected flood events, but also to detect any stormwater drainage system damage. As discussed in some case considered, any prolonged malfunction over time could be responsible of important structural defects of bridges, localized at piers and abutments base. In these cases, fast and very cheap interventions may be planned at a territorial level, in order to reduce the current Overall Class of Attention (O-CoA, Level 2). Acknowledgements This study was supported by FABRE – “Research consortium for the evaluation and monitoring of bridges, viaducts and other structures” ( https://www.consorziofabre.it/) within the activities of the FABRE-ANAS 2021-2024 research program. Any opinion expressed in the paper does not necessarily reflect the view of the funder. References Biondini, F., Ballio, F., di Prisco, M., Bianchi, S., D’Angelo, M., Zani, G., Capacci, L., Anghileri, M., Scialbi, A., Flores Ferreira, K., 2022. Bridge Vulnerability and Hazard Assessment for Risk-Based Infrastructure Management. 11th International Conference on Bridge Maintenance, Safety and Management (IABMAS 2022), Barcelona, Spain. Blöschl, G., Hall, J., Viglione, A., Perdigão, R. A. P., Parajka, J., Merz, B., Lun, D., Arheimer, B., Aronica, G. T., Bili bashi, A., Boháč, M., Bonacci, O., Borga, M., Čanjevac, I., Castellarin, A., Chirico, G. B., Claps, P., Frolova, N., Ganora, D., … Živković, N. (2019). Changing climate both increases and decreases European river floods. Nature, 573(7772), 108 – 111.