A multilevel fluid/structure model for predicting the damage behavior induced by flash floods in masonry structures

In recent years, the increased frequency and intensity of flash flood events have posed significant risks to urban infrastructure, particularly masonry buildings. Understanding the structural behavior of these constructions under such extreme conditions is crucial for enhancing their resilience and mitigating potential damages. This study addresses this challenge by developing a 3D multilevel fluid/structure model to simulate the fluid-structure interactions that occur during flash floods, providing valuable insights into the dynamic response and failure mechanisms of masonry buildings. In particular, the proposed model takes advantage of two sub-models: the first is a macroscale fluid model able to simulate the dynamic free-stream flow of a fluid impacting rigid surfaces defined by suitable boundary conditions. It relies on the Navier-Stokes equations and the standard two-equation k-e model to describe the flow and the turbulence effects, respectively, of the fluid. The second one is a mesoscale structural model, based on a damage-plasticity material approach, able to solve the nonlinear structural problem of classical masonry buildings under fluid pressure previously computed by the fluid dynamic analysis. Both sub-models are suitably validated by performing standard benchmarks, such as dam-break flow and flood-exposed masonry walls, and by comparing the obtained results with experimental and numerical outcomes available in the scientific literature. Subsequently, the proposed multilevel model is employed to simulate the structural response of real-scale masonry constructions under flooding. Parametric analyses are performed by varying the main flow characteristics, such as water depth and inlet velocity, in order to evaluate the different damage scenarios leading to the masonry building failure.