Experiment and Research on Calculation Methods on Flexural Mechanical Behaviors of Non-Metallic Reinforced ECC Beams

Engineered cementitious composites (ECC) has high tenacity and the characteristics of strain hardening. In the bending test, ECC beams equipped with carbon fiber reinforced polymer (CFRP) in the tensile region show good deformation ability and bending ability. In this paper, the constitutive models of ECC and CFRP materials are established by uniaxial tensile compression test. Based on the plane section supposition, the analysis theory of bending capacity of cross section for ECC beams with non-metallic reinforcement is proposed. The calculation results are compared with the four-point bending test results. The results show that: (1) ECC beams with non-metallic reinforcement reflect the advantages of the two materials, and have strong deformation capacity before bending failure. (2) The calculation results based on the theory of flexural capacity of normal section are in good agreement with the experimental results, and the maximum error is less than 4%. The research results can provide the basis and reference for the calculation analysis and practical application of non-metallic reinforced high toughness material structure.

Load-Bearing Capacity of Beams Reinforced with Composite Rebar in Regard to Existing Guidelines

Non-metallic reinforcement such as fiber-reinforced polymer (FRP) is now being increasingly used in construction. Despite numerous similarities, elements reinforced with non-metallic bars work differently from the ones reinforced with steel bars, including cracking and failure mode. The examination of the stress state in these elements, so important for their proper design, raises many difficulties. The article presents the results of tests of bended beams reinforced with GFRP bars. The results of the experimental tests were compared with calculations based on selected design instructions. The results have shown that beams reinforced with GFRP exhibit increased cracking, higher deflection, and often mode of failure through crushing of concrete. The results have shown that in bended elements reinforced with the GFRP bars, the rebar often does not achieve the strength declared by the manufacturer. The study has shown that theoretical values of load-bearing capacity of beams reinforced with composite rebar differ greatly between different guidelines and instruction. The analysis showed that the use of GFRP bars as a replacement for steel bars is possible in demanding environmental conditions. However, excessive deflections and cracks may result in limited application due to overall serviceability requirements of the element.

Prospects For Application Of Non-Metal Composite Valves As Working Without Stress In Compressed Elements

An analysis is given of the possibility of using glass-composite non-metallic reinforcement in compressed concrete elements. The results of comparison of studies of strength and deformability with high-strength composite and steel (class A800) working reinforcement in our country and abroad are presented. Proposals are given for further research of composite reinforcement as longitudinal in compressed elements.

The Use of Non-Destructive Testing (NDT) to Detect Bed Joint Reinforcement in AAC Masonry

Detecting non-metallic reinforcement made of FRP (Fibre Reinforced Polymers) can be problematic, particularly at the stage of work inspection and constructional evaluation. In contrast to steel reinforcement, detecting non-metallic reinforcement is difficult using NDT (Non-Destructive Testing) techniques. These difficulties mainly arise from considerably lower density, radiation resistance or electromagnetic impedance and cross-section of rebars when compared to steel reinforcement. Specific problems with the reinforcement detection are experienced in masonry structures, in which reinforcement is laid in bed joints. Measurements are made on a masonry face in the plane perpendicular to the reinforcement plane, and not the parallel one compared to reinforced concrete structures. Thus, the interpretation of results obtained from NDT can be complicated due to many physical phenomena occurring during tests, methods of presenting measurements and their accuracy. This paper compares different testing techniques used to detect non-metallic reinforcement in the masonry wall made of autoclaved aerated concrete (AAC). For the purpose of the tests, fibreglass and basalt meshes, traditional steel trusses and steel wire meshes were placed in bed joints of the masonry wall. An ultrasonic tomography and GPR (Ground-Penetrating Radar) scanner operating within a broad range of frequencies were used for the tests. We also used the electromagnetic device to detect metal meshes. As expected, the tests confirmed problems with detecting the non-metallic reinforcement. Only the radar method was effective in detecting the non-metallic method, whereas other methods failed. The electromagnetic method detected only the steel reinforcement in the masonry.

Comparative Analysis Of Bending Concrete Elements Reinforced With Steel And Fiber-Glass Reinforcement

The main advantages and disadvantages of using non-metallic composite reinforcement as a reinforcing element of bending concrete structures without pre-stressing are considered. The characteristics of composite and steel reinforcement are compared. Numerical comparative analysis of strength and deformation characteristics of bending concrete elements with plastic and steel reinforcement is performed. It is established that to ensure the strength of the normal sections of the bending elements, the consumption of non-metallic reinforcement is up to 40% higher than that of steel reinforcement. Results of calculations on deformations according to which rigidity of the bending designs reinforced with steel reinforcement is 15-20% higher, than for reinforced with non-metallic reinforcement are presented. The conclusion is substantiated that the use of non-metallic composite reinforcement in non-stressed bendable concrete structures is impractical. Recommendations on the possible use of plastic reinforcement in building structures are presented, as well as directions and prospects for further research are outlined.

Analysis of Deflection and Cracking of Concrete Beams with Non-Metallic Reinforcement

The composite bars have become a useful substitute for conventional reinforcement in civil engineering structures for which load capacity and resistance to influences of environmental factors' are required. Considering the requirements of responsible design of engineering structures with particular emphasis on durability, the use of non-metallic reinforcement in reinforced structural elements allows to reduce the costs related to erection of buildings, as well as the costs of building maintenance and renovations. The behaviour of model beams made of concrete reinforced with composite bars (fiber reinforced polymer bars) in three-point bending test was analyzed. The strength parameters of composite bars were tested. The bending capacity, deformation of concrete, and beam deflection were determined. Crack propagation in the model beams under load was analyzed using the Aramis 5M optical measuring system. Due to the strength characteristics of the composite reinforcing bars, the beams exhibited significant tensile strains, which resulted in the development of cracks of considerable width.

The Use of Non-destructive Methods to Detect Non-metallic Reinforcement in Concrete and Masonry

An increasing use of non-metallic reinforcement is problematic as it has to be detected at the stage of accepting construction works, or later when expert opinions are prepared for the building. In contrast to metallic reinforcement, location of this type of reinforcement is difficult using non-destructive techniques. Small diameters of rebars and their location in a tested element were troublesome. This article describes an attempt to locate non-metallic reinforcement in a concrete element and the masonry. Tests were performed using an ultrasonic tomograph and GPR with a broad range of frequencies.