Thesis is applied to the study of the stress-strained state of concrete beams reinforced carbon fiber-based composite materials in stretched, fine-grained concrete and steel-fiber concrete in compressed zonesfor the actions of a single and low-cycle loading. New experimental data concerning the carrying capacity, deformation and fracture of the reinforced concrete beams reinforced carbon fiber-based composite materials in stretched, fine-grained concrete and steel-fiber concrete in compressed zones. The system of carbon-reinforced plastics for reinforcement of the stretched zone of reinforced concrete beams is represented by two types of reinforcement products: carbon fiber plastic tape Sika® CarboDur® S-512 for reinforcement of beam structures in the area of the bending moment and carbon fiber SikaWrap®-230 C/45 and creating a clip. To enhance the compressed zone of reinforced concrete beams, fine-grained concrete of class C16/20 and 3% wire fiber 50 mm long were used; the layer thickness was 50 mm. The concrete matrix for all samples was made from a single concrete composition. For research was made twelve research beams. Reinforced concrete beams with dimensions of 100 ? 200 ? 2000 mm, concrete of class C16 / 20. Longitudinal working core reinforcement 2?10 A 500С and transverse reinforcement ?6 А240С with a step of 50 mm, except for the zone of pure bending. Upper mounting fittings from wire ?4 В500 (Вр-I). Carbon fibers - a material consisting of thin filaments with a diameter of 5 to 15 microns, formed mainly by carbon atoms. Composite tapes consist of 99% carbon fibers placed in 1% synthetic fibers. Steel fiber concrete is a composite material with a concrete matrix, reinforced with short steel fibers - fibers with a diameter of df = 0.25 ... 1.2 mm, with a ratio of length to diameter lf / df = 50 ... 120, volume content ?fv = 0.5 ... 3% Experimental studies of the strength of normal cross sections, stiffness and crack resistance of bending reinforced concrete beams before and after reinforcement with composite materials based on carbon plastics in the stretched zone, concrete and steel fiber concrete in the compressed zone, for the actions of single and low-cycle loads of various levels on them were performed. Reinforcement of flexible concrete elements increases the carrying capacity. With a single load, there was an increase in bearing capacity: in beams reinforced with concrete by 57%, in beams reinforced with steel fiber concrete by 46%. With a low-cycle load for the first by 32%, for the second by 60.9%. For beams reinforced under concrete load by 66%, in beams reinforced with steel fiber reinforced concrete by 65%. It has been established that reinforcement reduces deflections of reinforced concrete beams, in beams reinforced with concrete by 50%, in beams reinforced with steel fiber concrete by 40%. With a low-cycle load for the first at 16%, for the second at 10%. For beams reinforced under load by concrete by 10%, in beams reinforced with steel fiber reinforced concrete by 9%. The moment of cracking in reinforced beams doubled, and this indicates an increase in their stiffness. The width of the opening of normal cracks in concrete and the deformation of internal steel reinforcement also decreased. It has been established that the amplification system increases the carrying capacity of the beams and crack resistance, postpones the time of formation of the first crack, significantly reduces the width of the disclosure of a normal cracks compared to beams without reinforcement. A method for calculation of reinforced concrete beams reinforced with composite materials on the basis of carbon plastics in the stretched zone, steel fiber concrete in the compressed zone. Recommendations were composed for practical use of the research findings.
