Bond Behavior of GRFP Bars to Concrete in Beam Test (original) (raw)
Related papers
Beam Bond Tests of GFRP and Steel Reinforcement to Concrete
Archives of Civil Engineering, 2018
The paper presents research program of bond between glass fiber reinforced polymer bars and concrete in reference to the steel bars. Bond between the reinforcement and concrete is a crucial parameter governing a behaviour of reinforced concrete members and transferring of the internal forces from concrete to the reinforcement. The use of FRP bars as an equivalent reinforcement to steel in concrete structures has increased in recent years. The FRP bars are very different from steel, mainly due to much lower elasticity modulus and their anisotropic structure. Good performance of FRP reinforced concrete requires sufficient interfacial bond between bars and concrete. However, there are no specific standards referring to the surface preparation of these bars, that leads to variable bond behaviour of the composite reinforcement to the concrete. The objective of the study was to investigate the influence of variable parameters on the bond behaviour to concrete. The experimental program con...
Effect of Bonding Area on Bond Stress Behavior of GFRP Bars in Concrete
Civil Engineering Journal, 2023
The application of Glass Fiber Reinforced Polymer (GFRP) bars is suitable for concrete structures that are susceptible to corrosion, owing to their corrosion-resistant characteristics. Therefore, it is feasible to reduce the concrete cover on reinforced concrete beams by utilizing GFRP bars. However, this can reduce the bonding strength between GFRP bars and concrete. Therefore, this study aims to investigate the bonding behavior between GFRP bars and concrete as a preliminary test for structural applications. The bond stress behavior between GFRP bars and concrete was analyzed by 18 pull-out tests. The test specimens comprised GFRP bars with three different variations, namely GFRP bars with concrete cover (GFRP-C), GFRP bars without concrete cover (GFRP-E), and GFRP bars with a complete wrapping of GFRP sheet (GFRP-C-Sheet). The bond stress-slip curve, bond strength, and failure pattern were utilized to analyze the effect of each variation. The research results indicate that the bonding stress between GFRP bars and concrete was strongly influenced by the concrete cover, where the bonding strength decreased by 65%. Nevertheless, the utilization of a complete wrapping GFR) sheet resulted in a 26.4% increase in bonding stress. The present study has identified three distinct modes of failure, including pull-out (GFRP-C), concrete crushing (GFRP-E), and GFRP sheet debonding (GFRP-C-Sheet).
Bond behavior of Concrete Beam Reinforcement by GFPR Bars
2014
In recent years, some attempts have been performed to extend general design rules reported in the codes for steel reinforced concrete to Fiber Reinforced Polymer (FRP) materials; this is the case of relationships adopted in the evaluation of the development length clearly derived by extension of the formulations used for steel bars. However, such relationships seem to be inappropriate for FRP reinforcing bars: in fact, experimental test results have shown that bond behavior of FRP bars is different from that observed in case of deformed steel ones. As a consequence, a new procedure for the evaluation of development length based on an analytical approach is needed in order to directly account for the actual bond-slip constitutive law as obtained by experimental tests on different types of FRP reinforcing bars. During this research contribution, an experimental study of GFRP bar concrete bond test is carried out and presented to investigate the bond stress–slip behavior for normal and...
Investigation of bond in concrete member with fibre reinforced polymer (FRP) bars
Construction and Building Materials, 1998
Bond strength of fibre reinforced polymer FRP rebars was experimentally investigated in this study and compared to that of steel rebars. A total of 64 concrete beams reinforced with two types of FRP rebars, respectively, were tested. Four nominal diameters of FRP and steel rebars, namely, 12.7, 15.9, 19.1 and 25.4 mm and three embedment lengths, six, 10 and 16 times the rebar diameter were used. Moreover, three concrete depths of 200, 600 and 1000 mm were investigated in the 18 pullout specimens. Results of the tests indicated that the applied tensile load approached the tensile strength of rebars as the embedment length increased and the GFRP rebars showed lower bond strength values compared to steel rebars. The average maximum bond strength of the FRP rebars varied from 5.1 to 12.3 MPa depending on the diameter and the embedment length. The GFRP rebars showed lower bond strength values compared to steel rebars. A modification factor of 1.30 is recommended for computing the development length, to account for the top bar effect. A new model is proposed for the ascending branch of the bond᎐slip law.
Buildings
It is becoming accepted that glass-fibre-reinforced polymer (GFRP) is a credible and effective replacement for steel in reinforced concrete (RC) to meet structural requirements whilst addressing durability concerns posed by steel over the long term. A better understanding of the bond behaviour between GFRP and concrete is essential for reliably and efficiently designing concrete structures with reinforced GFRP bars. This paper presents a parametric study of the bond behaviour of GFRP bars to concrete where the effects of the length, diameter, concrete strength, concrete cover thickness and rebar surface morphology of GFRP bars were investigated via a series of pull-out tests. The test results indicate that the bond strength of GFRP bars is predominantly influenced by their surface morphology, embedment length and diameter. On the other hand, the effects of concrete strength and cover thickness appear to have a limited impact on the bond strengths of GFRP rebars to concrete. It is sh...
Bond mechanism and bond strength of GFRP bars to concrete: A review
Glass fiber-reinforced polymer (GFRP) reinforcements are taken as an alternative solution for the deterioration of civil infrastructures. GFRP bars have received increasing attention due to low cost compared to carbon fiber-reinforced polymer (CFRP) bars. Bond characteristic of GFRP bars in concrete is the most critical parameter for implementation of the material to the corrosion-free concrete structures. Unlike steel reinforcement, GFRP materials behave anisotropic, non-homogeneous and linear elastic properties, which may result in different force transfer mechanism between reinforcement and concrete. With the purpose of covering the most valuable contributions regarding bond mechanism in the past work, a comprehensive review focusing on the failure mode and bond strength is carried out in this paper. A database consisted of 682 pullout-test specimens was created to observe the factors affecting bond behavior. Basic relationship between bond strength/slip and factors was analyzed accordingly. In addition , the development of bond degradation under environmental conditions, such as freezing-thawing cycling, wet-dry cycling, alkaline solutions and high temperature was presented thereafter. These environmental influences need to be further investigated.
Bond Behavior of Ribbed-Surface, Headed-End, GFRP Bars Embedded in High-Strength Concrete
Glass Fiber Reinforced Polymer (GFRP) bars as a proper substitute for traditional reinforcing steel bars not only eliminate the durability problem due to corrosion of reinforcing steel, but also provide remarkably enhanced capacity due to their high tensile strength compared to that of the steel bars. This paper presents the experimental findings of pullout tests conducted on GFRP bars embedded into highstrength concrete blocks covering different parameters. The studied parameters were bar diameter size, embedment length, bar end condition (headed), and concrete cover to bar. Based on the results of the parametric study, the bond stress was shown to be inversely proportional to the embedment length and bar diameter as expected. In addition, the smaller concrete cover appeared to have significant effect on bond stress, leading to side blow-out failure rather than bar pullout or concrete splitting in the case of headed-end GFRP bars. In addition, the GFRP bar with headed-end showed significant increase in pullout strength compared to that for the straight-end bars. Finally, an empirical expression was proposed to calculate the development length of GFRP bars with headed-end cast in high-strength concrete.
Bond Behavior of GFRP-reinforced lightweight concrete beams
Zenodo (CERN European Organization for Nuclear Research), 2023
More study is required to better understand the flexural behaviour and cracking performance of fiberreinforced polymer (FRP) bars used in lightweight concrete (LWC) beams because there is a paucity of experimental research in this field. This article describes an experimental investigation that evaluated the flexural behaviour, cracking capability, and bond-dependent (Kb) properties of beams made of lightweight concrete. There are three thin concrete beams in all (one of them reinforced with steel bars as a reference beam and the other beams reinforced with GFR bars) measured 150 mm wide x 300 mm deep x 2000 mm long were constructed and tested up to failure in four-point bending over a clear span of 1800 mm. The test parameters were: (a) reinforcement type (Steel bars and GFRP bars), and (b) concrete cover (20 mm and 35 mm). The test results included information on the cracking behaviour, deflection, crack width, reinforcing strain, flexural capacity, and mechanism of failure. The experiment's findings showed that the GFRP-reinforced beams behaved linearly to cracking until concrete crushing caused them to fail. Additionally, the predicted moment capacities of the GFRP beams were computed using the straincompatibility approach in the design standards. The outcomes showed that the experimental results and predictions had a good degree of agreement. According to the analysis of the kb factor, recommended Kb values for smooth GFRP bars are thus given as = 1.65 based on the experimental findings of the tested beams.
Bond of GFRP Bars in Concrete: Experimental Study and Analytical Interpretation
Journal of Composites for Construction, 2006
The local bond mechanics of glass-fiber reinforced polymer ͑GFRP͒ bars in normal strength concrete was investigated through experimental testing and analytical modeling. The experimental program was comprised of 30 direct tension pullout specimens with short anchorages. A novel test setup, specially designed so as to minimize the spurious influence of testing conditions on measured bond properties was adopted in the study. Parameters considered were the bar roughness and diameter, the size effect expressed by the constant cover to bar diameter ratio, and the external confining pressure exerted over the anchorage length by transverse externally bonded FRP sheets. Results of the study were summarized in the form of local bond-slip curves, whereby performance limit states were quantified by the amount of loaded end slip and bond strength. An analytical model of the bond stress-slip response of a GFRP bar was derived from first principles and calibrated against the test data of the present investigation. Using the calibrated model, design values for bond and slip were estimated with reference to the code limit state model for bond.