PSI - Issue 84

Alessandro De Iasio et al. / Procedia Structural Integrity 84 (2026) 952–958

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(Intel(R) Core(TM) i9-10980XE, 3.00 GHz, 16 cores utilised) resulted in simulation times of around 36 hours for the entire model and 9 hours for the equivalent models, i.e. x4 faster simulations when using equivalent wall models.

Fig. 4. Comparison between the entire model and the equivalent wall models: (a) Impact force and (b) displacement . 4. Conclusions This paper investigated the impact of waterborne debris on reinforced concrete (RC) viaduct piers in flash flood scenarios. In particular, the study focused on the accuracy of equivalent wall models for simulating the structural response of piers to such impacts. The pier of a real viaduct with a multi-cell hollow cross-section was considered. The debris was treated as log debris, meeting the minimum design parameters for debris impact design per ASCE/SEI 7-22. The impact was assumed to be orthogonal to the shorter cross-section side and compatible with physically justified inundation scenarios. Analyses were carried out with dynamic explicit Finite Element simulations implemented in the commercial software Abaqus. Impact simulations were initially carried out by modelling the entire viaduct pier to obtain reference results for global and local structural behaviour. Successively, different equivalent wall models were analysed. Results showed that the structural response of the pier was mostly local around the impact area. At the same time, the rest of the structure experienced displacements up to two orders of magnitude lower. As such, the equivalent wall was taken as the part of the structure that locally displaced under the impact action, resulting in a wall having the same width as the pier cross-section, height equal to twice the impact distance from the ground level, and thickness equal to the pier cross-section thickness. Two sets of boundary conditions were considered: one with fully fixed edges and one with mixed fixed-supported edges. Data showed that both equivalent wall models accurately replicated the impact force, whereas only the fully fixed model accurately estimated the peak displacement. These results demonstrated the potential of these equivalent wall models, provided that appropriate boundary conditions are implemented, with significant advantages in computational time (x4 faster simulations in the presented research). Future studies will generalise such boundary conditions for different pier geometries and impact locations. Acknowledgements This research is included in the 2025/2027 Activity Plan of the HPC4DR Consortium (High Performance Computing for Disaster Resilience) for structural analysis and vulnerability under extreme flood actions. References Abaqus, 2024. Abaqus User Manual. Dassault Systèmes Simulia Corp. ASCE, 2022. Minimum Design Loads and Associated Criteria for Buildings and Other Structures (ASCE/SEI 7-22).