Bond clause proposals for FRP bars/rods in concrete based on CEB/FIP Model Code 90. Part 1: Design bond stress for FRP reinforcing bars

2006 ◽  
Vol 7 (2) ◽  
pp. 47-55 ◽  
Author(s):  
R. Tepfers
Keyword(s):  
Bond Stress ◽  
Reinforcing Bars ◽  
Model Code ◽  
Frp Bars

Stress along tensile lap-spliced fibre reinforced polymer reinforcing bars in concrete

2007 ◽  
Vol 34 (9) ◽  
pp. 1149-1158 ◽  
Author(s):  
Ragi Aly
Keyword(s):  
Mathematical Model ◽  
Large Scale ◽  
Bond Stress ◽  
Experimental Results ◽  
Reinforcing Bars ◽  
Reinforced Polymer ◽  
Pullout Tests ◽  
Fibre Reinforced Polymer ◽  
Displacement Theory ◽  
Frp Bars

A theoretical study was carried out to investigate stress along tensile lap-spliced spaced or bundled fibre reinforced polymer (FRP) bars in concrete. R. Tepfers developed a mathematical model, which could be applied for any type of reinforcing bar, based on the modulus of displacement theory. The mathematical model can predict the bond stress and stresses in the reinforcing bars and the surrounding concrete. In this paper, the model developed by Tepfers was represented by applying the modulus of displacement theory, and theoretical predictions are compared with the experimental results from testing 16 large-scale concrete beams. Good agreement between the theoretical values and experimental results was observed at three stages of loading. Recommendations for investigating the modulus of displacement from pullout tests have been included. Lastly, the maximum average bond stress of spliced FRP bars can be estimated using the ultimate failure pattern analysis, in which the contributions of the splitting resistance were included.Key words: beams, fibre reinforced polymer (FRP) bars, bundled bars, concrete, tensile lap-splice, pullout tests, modulus of displacement, flexural tests.

scholarly journals Modeling Local Bond Stress–Slip Relationships of Reinforcing Bars Embedded in Concrete with Different Strengths

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3701
Author(s):  
Chao-Wei Tang ◽  
Chiu-Kuei Cheng
Keyword(s):  
Prediction Models ◽  
Concrete Strength ◽  
Bond Stress ◽  
Analytical Models ◽  
Test Results ◽  
Reinforcing Bars ◽  
Model Code ◽  
Steel Bar ◽  
Proposed Model ◽  
Comparison Results

Although many different analytical models of local bond stress–slip have been proposed, considering the possible differences between materials in different countries, their applicability needs to be further explored. In this paper, the local bond stress–slip characteristics of reinforcing bars embedded in concrete with different strengths were experimentally studied. The experimental variables included the concrete strength (20, 40, and 60 MPa) and deformed rebar size (#4, #6, and #8). The experimental results of the bond stress–slip relationship were compared with the Euro-International Concrete Committee (CEB-Comité Euro-International du Béton)-International Federation for Prestressing (FIP-Fédération Internationale de la Précontrainte) Model Code and prediction models found in the literature. In addition, based on the test results, an empirical model of the bond stress–slip relationship was proposed. The evaluation and comparison results show that, regardless of the concrete strength grades, the predicted value calculated using the CEB-FIP Model Code will underestimate the bond strength of the specimens with different steel bar diameters. From this perspective, it is more conservative. In contrast, the proposed model can predict the test results with a reasonable accuracy.

Experimental Study on Bond Behavior of GFRP-to-Cement Mortar

2011 ◽  
Vol 94-96 ◽  
pp. 543-546
Author(s):  
Ning Zhang ◽  
Ai Zhong Lu ◽  
Yun Qian Xu ◽  
Pan Cui
Keyword(s):  
Aluminium Alloy ◽  
Cement Mortar ◽  
Bond Stress ◽  
Reinforcing Bars ◽  
Bond Performance ◽  
Gfrp Bars ◽  
Pull Out ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Average Bond

Direct pull-out tests were performed to evaluate the bond performance of glass fiber-reinforced polymer (GFRP) reinforcing bars in cement mortar. Specimens with different bar diameters and different grouted lengths (i.e., 5d, 10d and 15d, d is the diameter of bars) are prepared for the pull-out tests. For comparison, specimens with plain aluminium alloy bars (AAB) were tested as well. The result shows that the average bond stress between plain aluminium alloy bars and cement is much smaller than that between the deformed GFRP bars and cement; thin GFRP bars tended to have larger average bond stress; the shorter the grouted length, the smaller the maximum average bond stress. Only part of grouted length undertakes the bond stress and the length depends on the shear modulus of GFRP and the surrounding material.

Investigation of bond between fibre-reinforced polymer bars and concrete under sustained loads

2006 ◽  
Vol 33 (11) ◽  
pp. 1426-1437 ◽  
Author(s):  
F Shahidi ◽  
L D Wegner ◽  
B F Sparling
Keyword(s):  
Reinforced Concrete ◽  
Sustained Load ◽  
Reinforcing Bars ◽  
Bond Slip ◽  
Reinforced Polymer ◽  
Sustained Loads ◽  
Fibre Reinforced Polymer ◽  
Term Performance ◽  
Frp Bars

Although the use of fibre-reinforced polymer (FRP) bars to replace steel in reinforced concrete is becoming more common, uncertainty remains concerning the long-term performance of FRP, including the effect of a sustained load on the bond between the FRP bars and the concrete. An experimental study was therefore undertaken to investigate the long-term durability of the bond for various types of bars embedded in concrete: one type of glass FRP, two types of carbon FRP, and conventional steel reinforcing bars. Pullout specimens were tested both statically to failure and under sustained loads for periods of up to 1 year while free-end slip was monitored. Results revealed lower short-term bond strengths for FRP bars relative to steel and significant variability in long-term bond-slip performance among FRP bars of different types. Post-testing investigations revealed damage to bar surfaces at the macroscopic level, as well as broken longitudinal fibres and damage to the surface coatings at the microscopic level.Key words: reinforced concrete, fibre-reinforced polymer (FRP), bond, creep, pullout, sustained loads.

Evaluation on the Bond Stress-slip Relationship of GFRP Reinforcing Bars with Spiral Ribs

2018 ◽  
Vol 30 (1) ◽  
pp. 31-38 ◽  
Author(s):  
Hye-Jin Lee ◽  
Keun-Hyeok Yang ◽  
Si-Jun Kim ◽  
Sang-Hun Park
Keyword(s):  
Bond Stress ◽  
Reinforcing Bars ◽  
Relationship Of

NUMERICAL ANALYSIS OF CONCRETE BEAM REINFORCED WITH GLASS FIBER REINFORCED POLYMER BARS

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Osama A. Mohamed ◽  
Rania Khattab
Keyword(s):  
Finite Element ◽  
Numerical Analysis ◽  
Concrete Beam ◽  
Concrete Beams ◽  
Fiber Reinforced Polymer ◽  
Reinforcing Bars ◽  
Gfrp Bars ◽  
Reinforced Polymer ◽  
Steel Bars ◽  
Frp Bars

The use of fiber reinforced polymer (FRP) bars to reinforce concrete beams has received significant attention in the past decade due to their corrosion resistance, high tensile strength, and excellent non-magnetic properties. Glass FRP (GFRP) reinforcing bars have gained popularity due to the relatively lower cost compared to carbon FRP (CFRP) bars. In this study, sixteen concrete beam finite element models were created using the finite element computer program ANSYS to perform linear and non-linear analyses. Twelve beams were longitudinally reinforced with GFRP bars, while the remaining four beams were reinforced with conventional steel bars as control specimens. In terms of mechanical properties, FRP reinforcing bars have lower modulus of elasticity compared to conventional reinforcing steel and remain linear elastic up to failure. This leads to lack of plasticity and a brittle failure of beams reinforced with FRP bars. The objective of this study is to investigate flexural behavior of concrete beams reinforced with GFRP reinforcing bars. Some of the parameters incorporated in the numerical analysis include longitudinal reinforcement ratio and compressive strength of concrete, both of which affect the flexural capacity of beams. It is shown in this study that replacement of traditional reinforcing steel reinforced bars by GFRP bars significantly decreases mid-span deflection and increases ultimate load. The strain distribution along GFRP longitudinal reinforcing bars is totally different from that of traditional steel bars.

scholarly journals Experimental Study on Bond Behavior between Plain Reinforcing Bars and Concrete

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Guohua Xing ◽  
Cheng Zhou ◽  
Tao Wu ◽  
Boquan Liu
Keyword(s):  
Aluminium Alloy ◽  
Structural Characteristics ◽  
Bond Stress ◽  
Reinforcing Bars ◽  
Bond Slip ◽  
Bond Behavior ◽  
Reinforcing Bar ◽  
Test Parameters ◽  
Steel Bars ◽  
Plain Bars

To evaluate the bond behavior between the reinforcing bar and surrounding concrete, a total of six-group pullout specimens with plain steel bars and two-group specimens with deformed steel bars, serving as a reference, are experimentally investigated and presented in this study. The main test parameters of this investigation include embedment length, surface type of reinforcing bars, and bar diameter. In particular, the bond mechanism of plain steel reinforcing bars against the surrounding concrete was analyzed by comparing with six-group pullout specimens with aluminium alloy bars. The results indicated that the bond stress experienced by plain bars is quite lower than that of the deformed bars given equal structural characteristics and details. Averagely, plain bars appeared to develop only 18.3% of the bond stress of deformed bars. Differing from the bond strength of plain steel bars, which is based primarily on chemical adhesion and friction force, the bond stress of aluminium alloy bars is mainly experienced by chemical adhesion and about 0.21~0.56 MPa, which is just one-tenth of that of plain steel bars. Based on the test results, a bond-slip model at the interface between concrete and plain bars is put forward.

Crack Calculation of Beams Reinforced with FRP Bars Based on Linear Bond-Slip Model

2014 ◽  
Vol 919-921 ◽  
pp. 1377-1380
Author(s):  
Xiao Dong Li ◽  
Hao Chen Feng ◽  
Wei Ning Yuan
Keyword(s):  
Stress Distribution ◽  
Crack Width ◽  
Bond Stress ◽  
Distribution Model ◽  
Slip Model ◽  
Bond Slip ◽  
Frp Bars

This paper mainly gets a equation of crack width calculation. To get the result, the lineared bond-slip model between FRP bars and concrete is used, combining with the bond stress distribution model which is found by You Chunan. Finally, the value of this paper is compared with the value of ACI440.1R-06 and JSCE code, which prove the result is right.

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