the article deals with the issues of anchoring external composite reinforcement. The advantages of one of the reinforcement options are described - with the help of anchor harnesses. The procedure for performing work when reinforcing with anchor harnesses is presented. Also presented is a method for calculating pull-out anchors made of carbon fibers.

Keywords: reinforced concrete, concrete, composite materials, carbon fiber, reinforcement, external reinforcement, composite anchor

The results of experimental studies on the formation of cracks in reinforced concrete racks of two slenderness λh = 10 and 20, tested at three eccentricities of load application e0 = 0; 2.0cm (0.16h) and 4.0cm (0.32h). On the basis of the experimental data and the results of calculations on the formation of cracks, it was found that the values ​​of the theoretical moments of cracking of the experimental compressed elements differ significantly from the experimental ones. An analysis was made of the influence of the eccentricity of the load application and the flexibility of the samples on the convergence of the theoretical and experimental moments of cracking in the samples, and the possible reasons for the change in the bearing capacity of the samples were also considered.

Keywords: concrete, reinforced concrete, compressed elements, flexibility, eccentricity, crack, crack resistance

The article discusses the results of a survey of the technical condition of precast reinforced concrete columns of the building of the administrative building of the cotton mill in Shakhty. A calibration calculation for bearing capacity was made taking into account additional loads. Identified extensive damage the main ones are: - destruction of the protective layer of concrete, exposure and corrosive wear up to 10% of the cross section of the working and transverse reinforcement of columns; - cracks in the protective layer of concrete on the surface of the shelves of columns. The technical condition of the building structures of the administrative building for the period of the survey is assessed as unsuitable to the conditions of normal operation (partially operational). A calibration calculation was made and recommendations were developed for restoring the bearing capacity of precast concrete columns.

Keywords: concrete, bearing capacity, reinforced concrete, structures, reinforcement, constant load, strength, operational reliability, deformation, reinforcement

The history of development and efficiency of application of pipe-concrete structures during the erection of buildings and structures of various technical purposes is considered. The application of pipe-concrete columns for the purpose of restoring the operational reliability and load-carrying capacity of prefabricated reinforced concrete structures of the production building during its reconstruction is considered. Calculation of the bearing capacity taking into account additional loads and checking the strength of sections of the pipe-concrete column according to the deformation model have been made.

Keywords: concrete, pipe-concrete, load-bearing capacity, reinforced concrete, building structures, reinforcement, constant load, strength, operational reliability, deformation

The calculation by various methods and comparison of the economic efficiency of the use of metal, reinforced concrete and pipe-concrete columns during the development of the reconstruction project of the production building are considered. A technical and economic comparison is made for the following parameters: the mass of steel and concrete; cost of basic materials; labor intensity and cost of production. Analysis of options for calculating building structures can help in choosing the way to restore the operational reliability and load-bearing capacity of reinforced concrete compressed elements.

Keywords: concrete, pipe-concrete, load-carrying capacity, I-beam column, reinforced concrete, building structures, reinforcement, constant load, strength, operational reliability, deformation

To ensure sufficient strength, stability of buildings and structures, the possibility of their further normal operation, as well as during reconstruction, when it is necessary to increase the loads on existing structures, it is necessary to strengthen the damaged structures. Ways of strengthening and repairing damaged structures of buildings and structures can to a great extent differ both in technical and economic indicators and in the convenience of implementation, so that their proper choice in each particular case is extremely important. The article considers options for strengthening load-bearing building structures and verified computations for load-carrying capacity taking into account additional loads. The technical and economic comparison of the amplification variants in terms of the following parameters is made: the mass of the amplification elements; the cost of the basic materials needed to strengthen; labor intensity and cost of production; labor intensity and cost of performance of works on strengthening. Analysis of options for strengthening load-bearing building structures can help in choosing the method of reinforcing the load-bearing capacity of reinforced concrete bending elements.

Keywords: bearing capacity, reinforced concrete structures, reinforcement, constant load, strength, operational reliability, deformation

In this article, the problem of the application of high-strength steel reinforcement in flexible compressed reinforced concrete elements is considered. Conditions are considered for establishing the minimum necessary proportion of prestressed reinforcement in flexible columns with pre-stretched reinforcement with mixed reinforcement.

Keywords: concrete, reinforced concrete, structures, technologies, installation, reinforced concrete structures, tension, prestress, beams, reinforcement, efficiency

In this article, we consider ways to restore the operational reliability of reinforced concrete structures, the types of spacers, the method of reinforcing a reinforced concrete column with semi-circular steel sheets. The reinforcement of the elements by the biaxial transverse compression of concrete is also considered.

Keywords: concrete, reliability, reinforced concrete, structures, technologies, installation, reinforced concrete structures, struts, prestressing, columns, reinforcement, bearing capacity, reinforcement.