Research of the effect of changing the ratio of the content of steel and basalt-plastic reinforcement on the strength indicators of beams with hybrid reinforcement

Introduction.The current stage of development of the construction industry is associated with the introduction of new materials into practice, compared with the «traditional» (steel, concrete, wood) have certain advantages in the form of improved strength, corrosion resistance, etc. These materials include non-metallic composite reinforcement.Problems Statement. The main disadvantage of non-metallic composite reinforcement (except for carbon fiber reinforcement) is significantly lower modulus of elasticity compared to metal reinforcement. This is the reason for the occurrence of excessive deformations in concrete structures, does not ensure the fulfillment of the requirements for the second group of limiting states. One of the ways to reduce the de-formations of concrete structures, without a significant increase in the percentage of reinforcement of the section, is the use of hybrid reinforcement, when reinforcement is performed simultaneously with metal and composite reinforcement. Currently, there is a very limited amount of experimental data on the stress-strain state of structures with such reinforcement.Purpose. Research of the stress-strain state of structures with hybrid reinforcement, establishing its effectiveness and the optimal ratio of the content of metal and composite reinforcement to achieve sat-isfactory strength and stiffness of a concrete structure.Materials and Methods. The work of beams under load, reinforced with basalt-plastic reinforce-ment, metal reinforcement (control series) and with hybrid reinforcement with metal and basalt-plastic re-inforcement simultaneously was researched. To find out the effect of changes in the content of basalt-plas-tic reinforcement in relation to metal on the performance of beams with hybrid reinforcement, various series of samples of beams with different ratios of basalt-plastic and metal reinforcement.Results. On the basis of the conducted studies, the nature of the work and destruction of concrete beams with hybrid reinforcement was assessed depending on the percentage of metal and basalt-plas-tic reinforcement. The strength indicators of concrete beams with hybrid reinforcement were obtained and analyzed. The test results showed that the strength of beams with hybrid reinforcement increased in comparison with beams of the control series and was at the level of beams reinforced with basalt-plastic reinforcement. At the same time, the deflections and crack width of the beams decreased.Conclusion. The use of hybrid reinforcement makes it possible to increase the bearing capacity of concrete beams, depending on the percentage of reinforcement in the section. The determining factors for the strength of beams with hybrid reinforcement are the strength of the concrete in the compressed zone and the percentage of section reinforcement. The optimal percentage of the ratio of metal and basalt reinforcement in concrete beams with hybrid reinforcement is 60 % / 40 %.Keywords:beams with hybrid reinforcement, basaltoplastic reinforcement, steel reinforcement, strength, deformability.