PSI - Issue 62

L. Innocenti et al. / Procedia Structural Integrity 62 (2024) 661–668 / Structural Integrity Procedia 00 (2019) 000 – 000

667

7

denoting the influence of the relative independent variable while the other ratios are constant. Regarding the relation between Φ debris and Δ A , Melville and Dongol (1992), Lagasse et al. (2010) and Pagliara and Carnacina (2011) illustrated that scour depth varies highly on debris width multiplied by debris thickness. Finally, Ebrahimi et al. (2020) carried out a multiple linear regression using literature data, concluding that the maximum local scour depth around piers considering the effect of debris accumulation, d s , from the scour depth without wood accumulation, d s, 0 , can be assumed equal to: = ǡͲ (6) 3. Conclusions The paper drafts a methodology for the evaluation of the effects of wood accumulation at bridges as a proposal for an update of the Italian technical standards for constructions (NTC 2018). The main aim is filling a gap of knowledge on the wood-related hydraulic issues that can pose under risk the bridge safety. First, the reference events for the evaluation of wood accumulation must be defined, based on the return period and on the potential wood entrainment caused by erosion or landslides. The probability of wood accumulation at bridges, then, depends on the possible interactions between LW and the structure, on the characteristics of the wood flux and of LW elements, and on the evidence of previous wood accumulation. In case of high probability of accumulation, the accumulation dimensions can be determined based on empirical relations that account for the flow velocity and the key-log maximum length. Finally, the scour at a bridge pier induced by wood accumulation can be derived considering the potential scour, without wood, and a correction factor that depends on the log dimension, submergence and blockage ratio. The application of the methodology requires hydraulic computations to identify the main hydraulic variables, i.e., water elevation and flow velocity upstream of the bridge, and the acquisition of technical information about maintenance and past events, as well as a careful evaluation of the expected log dimensions. Collaboration with bridge management authorities and local experts is foreseen to collect all the required information. Despite being only theoretically depicted, the methodology is based on sound literature formulations separately derived from experimental evidence and already applied to real test cases. A systematic application to additional test cases will help identify the most suitable approaches (e.g., 1D or 2D hydraulic modelling) and the expected confidence ranges for the accumulation size and connected scour. 4. Online license transfer All authors are required to complete the Procedia exclusive license transfer agreement before the article can be published, which they can do online. This transfer agreement enables Elsevier to protect the copyrighted material for the authors, but does not relinquish the authors’ proprietary rights. The copyright transfer covers the exc lusive rights to reproduce and distribute the article, including reprints, photographic reproductions, microfilm or any other reproductions of similar nature and translations. Authors are responsible for obtaining from the copyright holder, the permission to reproduce any figures for which copyright exists. Acknowledgements L. Innocenti’s and L. Solari’s contributions were supported by the project “A new interdisciplinary approach to advance understanding of sediment and large wood TRANSport in FORested Mountain catchments - TRANSFORM” - PNR - NextGenerationEU (DM 737/2021 - DR 1395 del 15/11/2022).

References Benda, L., Miller, D., Sias, J., Martin, D., Bilby, R., Veldhuisen, C., Dunne, T., 2003. Wood Recruitment Processes and Wood Budgeting. American Fisheries Society Symposium, 37(January), 49 – 73.