Effect of Non-Metallic Composite Reinforcement on Load-Bearing Capacity

It is known that non-metallic composite reinforcement was invented in the 60's of the last century, and already then, a large number of scientists began to investigate its physical and mechanical characteristics. Despite its rather old age, this reinforcement has not been sufficiently studied for its work in building structures. Fiberglass composite reinforcement (Arvit) is a high quality construction material with many advantages: 4-5 times less weight compared to metal of the same diameter; it does not rust or oxidize; tensile strength is 2 times higher than metal reinforcement; it does not conduct electricity; high resistance to temperature changes from -70 to +200 ° C; easy to transport. The distinctive features of work of fiberglass composite reinforcement in bending spacer elements are still insufficiently studied, which in design and production practices leads to the non-use of such reinforcement in the construction of elements of buildings and structures. The experimental results of the test specimens are presented in the article. In first test specimen, longitudinal working reinforcement was made of two metal rods Ø8 class A400S, in second - two fiberglass rods Ø8 AKS 600.

NONLINEAR DEFORMATION-FORCE MODEL OF A CONCRETE BAR WITH NON-METALLIC COMPOSITE REINFORCEMENT IN THE GENERAL CASE OF A STRESSED STATE

The article discusses a nonlinear deformation-force model of a concrete bar structure with a non-metallic composite reinforcement (NKA-FRP) in the general case of a stressed state, when all four internal force factors from an external load (namely, bending and twisting moments, transverse and longitudinal forces). A sufficiently deep and meaningful analysis of well-known studies on the selected topic is given. It has been established that the proposed nonlinear deformation-force model of a bar structure with FRP in the general case of a stressed state can be practically useful due to the possibility of its application in the design or reinforcement of beams, girders, columns and elements of rosette trusses of rectangular cross-section, which are operated under aggressive environmental conditions. This model can also be used to check the bearing capacity of existing FRP concrete bar structures, which operate not only under the influence of an aggressive environment, but also under conditions of a complex stress-strain state. In the course of the research, an algorithm was developed for determining the bearing capacity of the design section of a concrete rod with FRP under its complex stress state. General physical relations for the design section are given in the form of a stiffness matrix. The algorithm for calculating a concrete bar with FRP consists of a block for inputting the initial data, the main part, auxiliary subroutines for checking the conditions for increasing the load vector and depletion of the bearing capacity, as well as a block for printing the calculation results. At each stage of a simple static stepwise increasing load, the calculation is carried out by performing a certain number of iterations until the accuracy of determining all components of the deformation vector satisfies a certain predetermined value. The features and patterns of changes in normal and tangential stresses, generalized linear and angular deformations, as well as the equations of equilibrium of a concrete bar with FRP, which operates under the influence of an aggressive environment under conditions of a complex stress state, are also considered.

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.

Research of non-metal composite basalt reinforcement of periodic profile and prospects of its use

Introduction. The results of research of physical and mechanical characteristics of non-metallic composite basalt reinforcement obtained by researchers, in particular, the shear strength of basalt reinforcement, coupling of basalt reinforcement to concrete, leaching of basalt fiber, durability of structures reinforced with non-metallic composite basalt reinforcement.Problem Statement. In the road industry, the main part of the costs for repair and restoration of reinforced concrete structures of bridges and overpasses is associated with corrosion of metal reinforcement. The use of non-metallic armature is a promising fundamental solution to this problem. Technical characteristics allow to apply basalt armature for road construction, at strengthening of bridges, for enclosing designs, in the designs which are exposed to aggressive environments.The effect of the use of basalt reinforcement is obtained, in particular, from reducing the cost of construction through the use of reinforcement of smaller diameter (hereinafter Ø) compared to metal while providing the necessary strength characteristics, reducing the weight of structures with such reinforcement. Also, due to the absence of certain types of corrosion of the armature during operation, the durability of the structure increases, reduce or eliminate certain types of repair work.However, the use of non-metallic composite basalt reinforcement of periodic profile, made of basalt fibers, designed for reinforcement of concrete structures of transport structures, is constrained by the lack of a sufficient number of research results of the characteristics of such reinforcement. On the basis of such researches it will be necessary, further, to make changes in norms on designing, standards on test methods, etc.Purpose. Investigate the armature of one of the main manufacturers, which were manufactured at the time of the study in Ukraine. Determine the geometric dimensions, mass, color, temporary resistance, elongation after rupture of the basalt reinforcement of the periodic profile with a diameter of 6 mm, 10 mm. To process the results of tests of physical and mechanical characteristics of non-metallic composite basalt reinforcement of periodic profile with a diameter of 6 mm, 10 mm, analysis of test results. Develop, based on the conclusions of the analysis of test results, proposals for the requirements for non-metallic composite basalt reinforcement for public transport structures.Materials and methods. Experimental studies of physical and mechanical characteristics of basalt reinforcement of periodic profile type A, nominal diameter 6 mm, 10 mm, manufactured according to TU U V.2.7-25.2-34323267-001, in particular, the curvature of the bar, surface quality, color of reinforcement, inner diameter reinforcement, temporary resistance, elongation after breaking.Results. As a result of researches it is established that curvature of a bar, quality of a surface, color of armature correspond to TU U V.2.7-25.2-34323267-001. The inner diameter of the valve, for individualbars, exceeds the permissible deviations within 0.3 mm in accordance with TU U V.2.7-25.2-34323267-001, DSTU B V.2.7-312:2016. However, as a result of the analysis of the obtained mechanical characteristics it was found that such deviations do not significantly affect the values of the mechanical characteristics of the tested samples (they are not less than necessary).However, in the future, when using basalt reinforcement, it is necessary to check such reinforcement for compliance with the requirements of DSTU B B.2.7-312:2016 and compliance must be ensured.Determined for basalt reinforcement temporary resistance, elongation after breaking, respectively: for Ø 6 mm ― 1 105 MPa and 2,13 %; for Ø 10 mm ― 1 068 MPa and 2,10 %.Conclusions1. Analysis of research on non-metallic composite reinforcement has shown that in recent years, scientists have paid considerable attention to reinforcement, as they see the prospect of its widespread use in the future. Studies of basalt reinforcement have shown that it has high strength, low density, has sufficient resistance to alkaline environment.2. As a result of researches of armature with a diameter of 6 mm and 10 mm it is established that curvature of a bar, quality of a surface, color of armature correspond to TU U V.2.7-25.2-34323267-001, DSTU B V.2.7-312:2016. The inner diameter of the valve, for individual bars, exceeds the permissible deviations within 0.3 mm (according to TU U V.2.7-25.2-34323267-001 and DSTU B B.2.7-312:2016). However, as a result of the analysis of the obtained mechanical characteristics it was found that such deviations do not significantly affect the values of the mechanical characteristics of the tested samples (they are not less than necessary). However, in the future, when using basalt reinforcement, it is necessary to check such reinforcement for compliance with the requirements of DSTU B V.2.7-312:2016 and compliance must be ensured.3. Defined for basalt reinforcement temporary resistance, elongation after breaking, respectively: for Ø 6 mm ― 1105 MPa and 2,13 %; for Ø 10 mm ― 1068 MPa and 2,10 %.4. The strain corresponding to the maximum static tensile load (Pmax) before the failure of basalt reinforcement samples was set when testing the reinforcement sample Ø 6 mm and is near 1153 MPa, which corresponds to the tensile strength of high-strength steel reinforcement class A-1000. The relative elongation of the basalt reinforcement δ is in the range from 2,0 % to 2,3 %, and is proportional to the δof the reinforcement A-1000, which is equal to 2,0 %.5. The results of tests for static loads show high performance characteristics of basalt reinforcement Ø 6 mm and Ø 10 mm, which is a prerequisite for the use of the tested reinforcement in the construction of transport facilities.Keywords:reinforcement, basalt, basaltoplastic, test, diameter, research, bridge, periodic profile, size, series, transport structure, characteristic.

Design of a Lightweight Multifunctional Composite Railway Axle Utilising Coaxial Skins

The rising economic and environmental pressures associated with the generation and consumption of energy necessitates the need for lightweighting of railway vehicles. The railway axle is a prime candidate for lightweighting of the unsprung mass. The reduction of unsprung mass correlates to reduced track damage, energy consumption and total operating costs. This paper presents the design of a lightweight multifunctional hybrid metallic-composite railway axle utilising coaxial skins. The lightweight axle assembly comprises a carbon fibre reinforced polymer composite tube with steel stub axles bonded into either end. The structural hybrid metallic-composite railway axle is surrounded by coaxial skins each performing a specific function to meet the secondary requirements. A parametric sizing study is conducted to explore the sensitivity of the design parameters of the composite tube and the stub axle interaction through the adhesive joint. The optimised design parameters of the axle consist of a; composite tube outer diameter of 225 mm, composite tube thickness of 7 mm, steel stub axle extension thickness of 10 mm and a bond overlap length of 100 mm. The optimised hybrid metallic-composite railway axle design concept has a mass of 200 kg representing a reduction of 50% over the solid steel version.