PSI - Issue 84

Available online at www.sciencedirect.com

ScienceDirect

Procedia Structural Integrity 84 (2026) 952–958

© 2026 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the Conference Keywords: RC viaducts; extreme flash floods; debris impact; FEM. Abstract Extreme flash floods are increasing in frequency and intensity due to climate change, and the built environment is at significant risk of structural damage from flood actions, including impacts from waterborne debris. Here, reinforced concrete (RC) viaducts are particularly vulnerable because they frequently cross floodplains. As such, viaduct piers are directly exposed to flash flood actions. These piers frequently have a rectangular box cross-section and various heights. Recent advancements have proposed different structural models to assess the impact forces exerted by waterborne log debris on wall structures, accounting for both structural and debris properties. This study aims to evaluate whether a wall-like model can be used to analyse the impacts of log debris on RC viaduct piers. High-fidelity simulations, directly representing the debris-structure interaction with debris and structure explicitly represented and interacting with each other, are used. An initial reference simulation of the entire pier is performed. Successively, an equivalent wall model is proposed to represent the pier portion impacted by the debris. Different boundary conditions are analysed. Results show that the equivalent wall can represent the local structural behaviour under debris impacts, provided appropriate boundary conditions are specified. This equivalent wall model is significantly advantageous in terms of computational costs. III Fabre Conference: Existing Bridges, Viaducts, and Tunnels: Research, Innovation, and Applications Equivalent wall model to analyse waterborne debris impacts on reinforced concrete viaduct piers Alessandro De Iasio a, *, Bahman Ghiassi b , Gabriele Milani c , Giovanni Fabbrocino a a Università degli Studi del Molise, Via De Sanctis 1, 86100, Campobasso, Italy b University of Birmingham, B15 2TT, Birmingham, United Kingdom c Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milan, Italy

* Corresponding author. E-mail address: alessandro.deiasio@unimol.it

2452-3216 © 2026 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the Conference 10.1016/j.prostr.2026.06.122