PSI - Issue 66

Umberto De Maio et al. / Procedia Structural Integrity 66 (2024) 486–494 Author name / Structural Integrity Procedia 00 (2025) 000–000

488

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Finally, the physical response of the building is evaluated using structural analysis and building physics to compare the resulting stresses. Based on a simplified quasi-static analysis, in (Xiao and Li, 2013) the failure process of a rural masonry building, induced by impact action of flood, is investigated considering the structure dissected into eight node block elements and Goodman elements to simulate brick and mortar. However, despite the great effort offer by the researchers for developing integrated numerical models able to analyze the flooding effects on the structure, there are notable research gaps in understanding the physical damage to buildings and the interaction mechanisms between flows and structures. In this context, the present work, aims to develop a numerical multilevel framework able to simulate flooding action and its effects on the structural behavior of masonry buildings in terms of load carrying capacity and damage patterns by using the computational fluid dynamics and a damage-plasticity model for the fluid flow and the structure, respectively. 2. Multilevel fluid/structure modelling In this section the proposed numerical framework to simulate the flash flood action and the structural behavior of masonry buildings is briefly explained. In particular, the urban flooding event is simulated using a macroscale model illustrated in Section 2.1, able to analyze fluid flow considering a rigid solid representing the building. This provides the “fluid pressure function” showing pressure distribution on the building’s surfaces over time. Meanwhile, a mesoscale model, described in Section 2.2, assesses the building's structural behavior, including load capacity and damage, under the computed pressure distribution by using a well-known damage approach. 2.1. Fluid model Based on the Computational Fluid Dynamics (CFD), a 3D numerical model is employed to simulate the free stream flow of the fluid and its interaction with surfaces defined by boundary conditions. In particular, this model relies on the Navier-Stokes equations and the standard two-equation k-  model to describe the flow and the turbulence effects of the fluid, respectively. The turbulence model introduces two dependent variables: the turbulent kinetic energy ( k ), and the turbulent dissipation rate (  ), providing a modified viscosity parameter � as follows: 2 T k C      (1) where C � and ρ are a model constant and the fluid density, respectively. The transport equations for k and  take the following forms:

T                              u k k P k T  k k t        u      



(2)

2





1 C P C   k



 

 

 

 

2



t

k

k







where C �� , C �� , σ � , and σ � are model constants determined from experimental data (Wilcox, 1994). 2.2. Structural model A refined 3D damage model is introduced to address the nonlinear structural behavior of a classical masonry structure under fluid pressure. Typically, damage models used in civil engineering rely on strain- or plasticity-based frameworks, such as the Mazars damage model for concrete (Ragueneau et al., 2000), phase field (Li et al., 2023) and cohesive approaches (Ammendolea et al., 2023; Gaetano et al., 2022), or the Drucker–Prager and Mohr Coulomb models. In this study, a plasticity model based on the Mohr-Coulomb (Chen and Mizuno, 1990), yield