One of the main tasks, which is solved at the design stage of the reinforced concrete element, is the analysis of the stress-strain state, as well as the determination of the service life. The article is devoted to modeling of nonlinear creep of reinforced concrete structural elements taking into account damages and return of the creep. The high priority of the research topic is substantiated, the purpose and objectives are formulated. A combination of a plastic model with fracture mechanics is proposed to simulate the behavior of concrete in accordance with its characteristics, including not only stress and deformation, but also the degradation of its stiffness. The resulting equations of state correspond to the law reverse deformations. The finite element method is used to solve the boundary value problem. For the sake of numerical modeling of thin-walled structures, the use of special shell elements is proposed. The mathematical formulation of the problem of creep of reinforced concrete structural elements taking into account anisotropy of material properties and creep deformations and return of the creep is presented. Creep problems of thin-walled structural elements were solved with the help of developed software. Analyzed the deformation of reinforced concrete panel of cylinder. The analysis of the results allows us to judge the effectiveness of the proposed model as a whole. The equation of state reflects the anisotropy of the material properties and takes into account the damage, which allows for a reliable assessment of the strength, stiffness and durability of reinforced concrete structures. Conclusions about the adequacy of the analysis of reliability and durability of reinforced concrete structures using the proposed model.

One of the main tasks that is solved at the design stage of a reinforced concrete structure and its elements is the analysis of the stress-strain state, as well as the determination of the service life of the structure. The article is devoted to modeling the nonlinear creep of reinforced concrete structural elements taking into account damage and shrinkage of concrete. The high priority of the research topic is substantiated, the goals and objectives of the research are formulated. A combination of a plastic model with fracture mechanics is proposed to simulate the behavior of concrete in accordance with its characteristics, including not only stress and deformation, but also the change in its characteristics over time. The obtained equations of state correspond to the incremental creep law, taking into account the damage and shrinkage. The finite element method is used to solve a boundary value problem. For the purpose of numerical modeling of thin-walled structures, it is proposed to use special shell elements. The mathematical formulation of the problem of creep of reinforced concrete structural elements taking into account creep deformations and volumetric deformations of concrete shrinkage is presented. The problems of creep of thin-walled structural elements were solved using the developed proprietary software. Deformations of a reinforced concrete cylindrical panel are analyzed. Analysis of the results allows us to judge the effectiveness of the proposed model as a whole. The equation of state reflects the properties of the material and takes into account damage, allows you to reliably assess the strength, rigidity and durability of thin-walled reinforced concrete structures. Conclusions are presented regarding the adequacy of the analysis of the reliability and durability of reinforced concrete structures using the proposed model.