During individual construction in seismic areas, the designer often has to solve problems that violate certain requirements of regulatory documentation on the configuration and number of storeys of the building, architectural and planning solutions of its internal and underground space. In this case, it is necessary to develop special technical conditions (STC) with compensating measures for these deviations, ensuring high seismic resistance of construction objects. The article considers the possibility of using the technology of plastic deformation of the bearing structural elements of the building to ensure the seismic resistance of the object, and also offers a method for assessing the degree of plastic work of the structure.

The results of studying the stability of the compressed pipe-concrete structures are given. Formulated the calculation principles and assumptions. Expressions for critical forces are given it is shown that the direct application of the formulas of existing regulations can lead to errors. The comparison of the results of calculation of critical forces at the given formulas with the experimental data is given.

Reinforced concrete is a non-linear material. This nonlinearity is determined by the nonlinearity of the behavior of concrete during compression and tension, the formation of cracks in tension during the deformation of the structure, as well as the nonlinearity of the work of the reinforcement. Accounting for non-linear work of reinforced concrete is necessary to obtain reliable data on the stress-strain state and strength of structures. But unlike, for example, from steel, the nonlinearity of reinforced concrete manifests itself in a more complex form.
At present, the calculation of buildings and structures, as well as difficult working units of structures is performed using computer programs. The results of numerical studies published in scientific publications and in the reports of scientific conferences show that, unlike metals, it is still extremely difficult to obtain calculated results for the stress-strain state of reinforced concrete structures strictly corresponding to the experimental data.

The paper presents the results of testing full-size flexural pipeconcrete structures, which are used in the actual building objects. Technology of the structures met the construction conditions. Formulae for structural design of such constructions are presented. The formulae are based on the classical principle of structural mechanics as a condition of equilibrium of external and internal forces acting in the cross-section, as well as the conditions of equilibrium of these forces moments. Comparison of experimental and calculated data has been performed. Confirmation of the fact that the formulae developed give the results in good agreement with the experimental values is presented.

In this article, numerical and experimental studies of the strength of compressed steel-reinforced concrete elements made using high-strength concrete and square steel pipes of class C345 are considered in order to determine the bearing capacity. The main issue in the calculation of pipe-concrete structures is the question of the design strengths of materials working as part of a pipe-concrete section. These strengths differ from the strengths of materials in a uniaxial stressed state and depend on a number of parameters. Concrete with small eccentricities of longitudinal force is in a state of triaxial compression, and its strength increases compared to uniaxial compression. The steel of the pipe is in a flat stressed state. When the eccentricity of the longitudinal force application increases, the strengths of materials approach to the strength under uniaxial compression. The issue of changing the strength of materials with a change in the eccentricity of the longitudinal force has been studied quite well. Therefore, the main issue is the strength of materials in the central compression of the pipe-concrete structure. The work of materials in the composition of a square tube-concrete section is fundamentally different from the work of materials in the composition of a round tube-concrete section. The main difference lies in the uneven lateral compression of concrete in a square pipe.