PSI - Issue 66

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

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criterion is employed to determine the stress conditions leading to plastic deformation, effectively defining the failure surface. According to this criterion, failure occurs when the shear and normal stresses on a material element meet the specified equation: tan 0 c       (3) where τ , c , and ϕ are the shear stress, cohesion and angle of internal friction, respectively. This criterion can be written by using the Mohr’s circle as follows:     1 3 1 3 1 1 sin cos 0 2 2            (4) This criterion forms an irregular hexagonal pyramid in the principal stress space. Additionally, to prevent predicting tensile strengths greater than those observed experimentally, a tension cut-off criterion is incorporated into the adopted method. The theoretical approach is then implemented into the commercial FE software, COMSOL Multiphysics. 3. Numerical results The numerical strategy has here employed to evaluate the structural response of a real-scale masonry construction subjected to the flooding phenomenon, already numerically analyzed by (Lonetti and Maletta, 2018). The first step of the analysis involves the macroscale fluid dynamic model to obtain the pressure distribution of the fluid on the structure walls. The geometric and boundary conditions of the urban area are reported in Fig. 1. In particular, a solid element, having the geometric dimensions of the building under observation, is subjected to a fluid flow with velocity U 0 and water depth H w . The water depth is taken constant and equal to 1 m, while three different initial velocities, equal to 1, 3, and 5 m/s are employed for the analyses. Outlet conditions are imposed at the perimetral walls of the test, while an inlet condition with a constant velocity field equal to U 0 is enforced at the water surface.

Fig. 1. Geometric and boundary conditions of the numerical test.

A dynamic analysis is conducted by adopting a time step equal to 0.2 s. The numerical results in terms of maximum pressure acting on the wall that is most affected by the fluid action, specifically the front wall facing the surface where the fluid inlet is set, are reported in Fig. 2. We can see that for each inlet velocity considered, the peak value of the pressure is recorded at the initial impact stage of the fluid on the wall, subsequently, the pressure value stabilizes at a constant value throughout the entire analysis.