This work is a continuation of a scientific study to determine the effectiveness of composite materials based on carbon fabric in the field of strengthening bending and compressed elements. The article is devoted to the determination of the geometric characteristics of prototypes, the description of the structure of the internal metal frame and the methodology for strengthening reinforced concrete samples. The importance of this scientific work lies in the fact that one of the most popular companies selling composite materials in Russia (“Gidrozo”) proposes to use a new technology for reinforcing reinforced concrete structures that differs from that recommended in the norms. However, according to the manufacturer's specialists, this technique not only ensures reliable adhesion and joint operation of reinforcement materials and structural concrete, but also significantly increases the efficiency of the composite material.

Keywords: steel, heavy concrete, reinforced concrete, composite material, reinforcement, carbon fiber, test, stand, beam, sample

Construction practice shows that in addition to the need to strengthen the supporting structures of buildings and structures, there is a need for repair and restoration work of reinforced concrete power transmission line supports. With local damage, followed by corrosion of the internal reinforcement, which plays the most important role in containing the resulting bending moments, modern reinforcement methods are either expensive or impossible to perform. In this scientific work, a proposal is presented to strengthen such structures by replacing damaged metal rods with new ones, while new rods are connected to existing special ferrules. The reinforcement process ends with the sealing of damaged areas with high-strength putty. The paper presents the amplification technology and presents all the positive properties of the new amplification method.

Keywords: heavy concrete, power transmission line support, reinforced concrete, compressed elements, coupling, reinforcement

Reinforced concrete structures with prestressed reinforcement are a problem when it is necessary to restore or strengthen them, especially when the prestressed reinforcement is damaged or has significant corrosion. Typically, such structures have large dimensions or cover large spans. Given the scale of work to replace such structures, the development of options for strengthening or restoration is an urgent issue. One of the most complex structures with prestressed reinforcement is a high-rise power line support with an annular section. Its work in the natural environment is exposed to destructive factors that lead to the removal and destruction of prestressed reinforcement. This article is devoted to the development of a method for strengthening the damaged section of the reinforced concrete pylon of a power transmission line by replacing and prestressing the destroyed rod. The paper presents the technology of the amplification method and the main positive properties.

Keywords: heavy concrete, power transmission line support, reinforced concrete, compressed elements, threaded coupling, reinforcement

This paper studies the dependence of the ratio of prismatic strength (Rb) from cube strength (R) for high-strength concrete of classes B70 ... B110. Experiments were carried on the concrete cubes with an edge of 150 mm and prisms with a base 150x150 mm and a height 600 mm. The tendency to reduce the ratio Rb / R with increasing strength of the concrete is founded. A new relationship Rb = f (R) is offered

Keywords: high-strength concrete, physical experiment, prismatic strength, cube strength, the coefficient of the prismatic strength

The paper proposes a new relationship for the analytical description of the diagram «b–b» for high-strength concrete of classes C55/67 ... C90/105. The formula developed on the basis of the accepted in EU relation of Sargin and agrees well with the experimental data. A new relation of the ultimate relative deformation of concrete from the strength is developed

Keywords: high-strength concrete, physical experiment, state diagram of concrete, the stress-strain dependence in concrete, the ultimate relative deformation of concrete

The article discusses issues related to the study of the influence on the deformability of concrete beams of heavy concrete reinforcing steel to replace the carbon fiber arranged in two rows. Found that delamination of the composite beams with reinforcement throughout the range of loads up to 46-54% compared with the reference.

Keywords: concrete, steel, carbon-fiber reinforcement, test samples, strength, steps of loading, deformability, cracking, load level

The article discusses issues related to the strength of the normal sections of reinforced concrete beams in which the steel reinforcement is completely or partially replaced by a carbon fiber rod arranged in two rows. Found that the strength of these beams is only 13% higher than that of the reference.

Keywords: concrete, steel, composite reinforcing, test samples, strength, failure modes, load level

An approach to the calculation of the optimal values ​​of the protective layer of longitudinally reinforced concrete columns, operating at a central compression. Modeling performed using FEM - Ansys package for the design and implementation of spatial models of flat section of the column.

Keywords: reinforced concrete column, longitudinal reinforcement, a protective layer of concrete, finite element method, critical load

The effect of not repeatedly re-exposure to the compressive strength of concrete elements of expanded clay-fiber concrete. The experimental results of reinforced concrete columns after repeated unambiguous and alternating loadings. The influence of repeated loading regimes on the bearing capacity, deformation and fracture of columns. Proposed dependence of the bearing capacity of the columns on the level of repeated loadings.
Keywords: Keramzitofibrobeton, bearing capacity, crack, deformation, reinforced concrete column, mixed reinforcement.

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The influence of non-multi - repeated loads on columns of keramzito fibrobetona. Comparative results of tests Depends on the flexibility of columns, the eccentricity of the external force, the coefficient of reinforcement options and loading. The obtained results suggest that repeated loading nemnogokratno increase the carrying capacity of columns, compared with a single loading. This is especially effective for columns with low flexibility and small eccentricities external force.
Keywords: stand, keramzitofibrozhelezobeton, bearing capacity, nemnogokratno repeated loading, mixed reinforcement flexibility.

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