ESTIMATED JUSTIFICATION OF TECHNICAL DECISION ON STRENGTHENING REINFORCED CONCRETE MACHINE HALL FLOOR

Introduction. In connection with the long-term operation of hydraulic structures (HPP), the installation of significant temporary loads, the presence of alternating effects on individual structural elements, it is possible to reduce the carrying capacity and strength of reinforced concrete structures. One of the most crucial elements is the reinforced concrete overlap of the machine hall, the work presents field and design studies, a proposal to strengthen the structures with external reinforcement. Materials and methods. The scientific and technical documentation was analyzed, instrumental studies and visual inspections of the state of the structures were carried out, and a 3D mathematical model was developed based on the finite element method. Multivariate non-linear computational studies of the actual stress-strain state of structures have been carried out. Results. Conducted visual and instrumental examination showed the presence of cracking on the lower edge of the reinforced concrete floor of the machine room. The simulation of the actual state of the structures has been carried out; according to the results of calculations, a schematic diagram of the gain of structures has been proposed. Conclusions. As a result of computational studies of stress-strain state, the occurrence of cracks on the lower edge of reinforced concrete floor of the machine hall was confirmed. When applying temporary technological loads to overlap, it is possible to achieve the yield strength of the reinforcement in certain zones. In order to ensure further safe operation of the structures, a conceptual amplification scheme based on the results of stress-strain state calculations has been proposed

The results of the experimental studies of reinforced concrete structures of hydraulic structures with interconnect construction joints, reinforced by external reinforcement of carbon fiber

For the purposes of experimental validation of application of external reinforcement of carbon fiber to reinforce reinforced concrete structures of hydraulic structures the experimental models of typical structures of hydraulic structures with inter-block construction joints were tested. At the same time, beam-type models of concrete of class B15 with a reinforcement percentage of 0.39 % and concrete of class B25 with a reinforcement percentage of 0.83 % were tested for the effect of bending moment. The models of fragments of reinforced concrete structures of hydraulic structures of concrete class B15 with a reinforcement percentage of 0.445 % and concrete B25 with a reinforcement percentage of 0.7 % were tested for сentral extension. Reinforced concrete beam-type models were reinforced with external reinforcement of carbon tapes of the type FibArm 530/300. Models of hydraulic structures fragments were reinforced by external reinforcement from carbon tapes of the type FibArm Tape 530/300 and from carbon composite lamellae of the type FibArm Lamel 12/50. The reinforced concrete beam-type models were reinforced with carbon strips (longitudinal bands on the lower stretched face and transverse belts in the span and supporting zones). The models of fragments of reinforced concrete structures of hydraulic structures were reinforced with carbon strips and carbon composite slats directed along the action of longitudinal tensile force. The results of experimental studies showed a significant increase in the strength of reinforced concrete structures of hydraulic structures due to their reinforcement by external reinforcement of carbon fiber, and also revealed a special character of the crack formation due to the presence of inter-block construction joints. Subject of the research: the subject of the study: reinforced concrete structures of hydraulic structures (with interblock construction joints), reinforced with external reinforcement of carbon fiber. Materials and methods: reinforced concrete models were made from ordinary heavy-weight concrete of classes B15 and B25 and reinforcement of A500C class. The outer reinforcement was made of carbon tapes of the type FibArm Tape 530/300 and FibArm Lamel12 / 50. Experimental studies were carried out on the basis of physical modeling of characteristic reinforced concrete structures of hydraulic structures with interblock building joints. In this model, the beam type of concrete class B15 with a percentage of reinforcement of 0.39 % and of concrete class B25 with a percentage of reinforcement 0.83 % were tested for the action of bending moment. Models of fragments of reinforced concrete structures of hydraulic structures from concrete class B15 with a reinforcement percentage of 0.445 % and of concrete B25 with a reinforcement percentage of 0.7 % were tested for the effect of central stretching. Experimental models were equipped with control and measuring equipment for determining the values of deflections, deformations of concrete and reinforcement elements of models, crack opening width and interblock joints. Results: in the course of experimental studies, a significant increase in the strength of reinforced concrete structures of the hydraulic structures (in 1.47-2.34 times) was obtained under the action of the bending moment and the central extension due to their reinforcement by external reinforcement from the carbon fiber. Conclusions: based on the obtained experimental data on the significant increase in the strength of reinforced concrete structures of hydraulic structures (by 1.47-2.34 times) due to reinforcement by carbon composite tapes and carbon composite lamella, the substantiation of the use of external reinforcement from carbon bands and lamellas under the action of a bending moment and central extension. Also, a special type of cracking was observed, due to the presence of interblock joints, the study of which allows controlling the implementation of technical solutions for reinforcing, repairing, reconstructing reinforced concrete structures of hydraulic structures

METHODOLOGY FOR STRENGTH ANALYSIS OF NORMAL CROSS-SECTIONS OF REINFORCED CONCRETE HYDRAULIC STRUCTURES STRENGTHENED WITH CARBON COMPOSITE MATERIALS

The way to strengthen concrete structures in civil engineering by adding external reinforcement using carbon fiber composites is widely spreading in recent years. A method for calculating the strength of reinforced concrete in hydro technical constructions with reinforcing by carbon fiber composite materials was invented with the aim to justify the solutions of strengthening concrete structures. It was taken into consideration that the characteristic features of mass reinforced concrete structure with sand operating loads which including backpressure of water in the cracks and in opened construction joints. It has evolved the relations for calculation of strength in normal cross section of bending reinforced concrete member of hydro technical constructions which strengthening with external reinforcement by carbon fiber