PSI - Issue 37

G. Gusev et al. / Procedia Structural Integrity 37 (2022) 425–430 Gusev G./ Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 2. ( a) А finite element model of a precast reinforced concrete building on a foundation plate. The figure shows the distribution of the third main stresses in the supporting frame of the building, MPa. The gray color shows the zones with exceeding the limit values according to the developed criteria.; (b) a finite element model of a monolithic reinforced concrete building on a foundation plate. The figure shows the distribution of the third main stresses in the supporting frame of the building. 3. Development of evaluation criteria Reinforced concrete is a complex composite material. In engineering, there are no strength criteria that allow us to assess its stress-strain state close to critical even when crossing this boundary. In this paper, the limiting level of the deformed state of reinforced concrete structures is determined. In reality, it is quite far from the values that are laid down in the regulatory documentation. Therefore, a criterion was developed that allowed us to approach the solution of the task. A number of separate finite element models have been created that simulate the behavior of individual critical structural components. A very high level of sampling was set in the models. The solution was made in a physically nonlinear formulation, taking into account the possibility of cracks in the concrete body and plastic deformations of steel reinforcement. The decision was made taking into account the loading time. A number of nodal points of the building were selected and the stress-strain state was modeled taking into account the deformations of the earth's surface using the submodeling method.

Fig. 3. (a) a finite element model of a node of a reinforced concrete structure. The presence of reinforcement is shown.; (b) qualitative distribution of the intensity of deformations at the moment before the destruction of the structural unit.

The goal was to bring the stress-strain state of the catch to critical and surpass it. During the loading process, the deformation energies in a representative volume of elements were calculated. Both concrete and rebar were included in this volume. The dependences of the deformation energy on the average compressive stresses in a representative volume and on the loading time steps are constructed.