Analysis of influence factors on interfacial bond between BFRP bars and seawater sea-sand concrete

2020 ◽  
pp. 073168442094160
Author(s):  
Yuntao Hua ◽  
Shiping Yin ◽  
Zihan Wang
Keyword(s):  
Bond Strength ◽  
Bond Length ◽  
Failure Modes ◽  
Influence Factors ◽  
Basalt Fiber ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Bond Slip ◽  
Pull Out ◽  
Reinforced Polymer

In this paper, the influences of parameters such as the bond length, surface textures of reinforcement, reinforcement type and stirrups restraint were considered. Pull-out failure, splitting failure and splitting-pullout failure modes were observed during the test. The slip at the free end always lagged behind the slip at the loading end and the bond-slip curve of ribbed basalt fiber reinforced polymer (BFRP) bars included the micro-slip stage, slip stage, descent stage, and residual stage. Reducing the bond length and using ribbed-sand coated bars were beneficial to improve the bond performance. Increasing the bond length from 2.5 d to 5 d reduced the bond strength by 49.2%. The application of ribbed-sand coated bars instead of plain bars increased the bond strength by 1202.3%. The difference in bond strength between steel bars, BFRP bars and glass fiber reinforced polymer (GFRP) bars was small and the bond strengths of the three were much greater than that of carbon fiber reinforced polymer (CFRP) bars. This was mainly attributed to the different rib forms of the bars. The application of stirrups increased the bond strength by 11.5%, which indicated that the stirrup restraints can improve the bond behavior to a certain extent. Besides, the analysis of the bond-slip curve based on the energy perspective was consistent with test results.

scholarly journals Experimental Studies on Bond Performance of BFRP Bars Reinforced Coral Aggregate Concrete

2019 ◽  
Vol 13 (1) ◽  
Author(s):  
Lei Wang ◽  
Zhaoping Song ◽  
Jin Yi ◽  
Jiayi Li ◽  
Feng Fu ◽  
...  
Keyword(s):  
Failure Modes ◽  
Fiber Reinforced Polymer ◽  
Constitutive Relationship ◽  
Fiber Reinforced ◽  
Ocean Engineering ◽  
Aggregate Concrete ◽  
Bond Slip ◽  
Bond Performance ◽  
Pull Out ◽  
Reinforced Polymer

Abstract Basalt fiber reinforced polymer (BFRP) rebars reinforced coral aggregate concrete is a new type of concrete used in ocean engineering. In order to investigate the bond performance between BFRP rebars and coral concrete, 30 pull-out tests were carried out in 10 groups with different diameters of BFRP rebars, bonding lengths and strength of the coral concrete. The results show that good bonding between BFRP rebars and coral concrete were achieved. The main failure modes can be categorized as BFRP rebars pull out destruction, splitting failure of coral concrete and BFRP rebars fracture. The bond slip ($$\tau{\text{-}}s$$ τ - s ) curves of the BFRP rebars and coral concrete were obtained during the tests. It was found to be similar to the common concrete using fiber reinforced polymer (FRP) bars. The bond-slip relation can be roughly divided into micro-slip phase, slip phase, decline phase, and the residual stress stage. The bond between BFRP rebars and coral concrete increases with the increase of the bond length and diameter of BFRP rebars, but the average bond stress will decrease. Moreover, increasing the strength of coral concrete is effective to improve the bond performance of BFRP rebars. In this paper, the continuous bond slip model (Gao et al. in J Zhengzhou Univ 23:1–5, 2002) was used to represent the $$\tau{\text{-}}s$$ τ - s constitutive relationship of BFRP rebars and coral concrete. The analysis show that the proposed model has a high degree of accuracy in representing $$\tau{\text{-}}s$$ τ - s curve of BFRP rebars and coral concrete.

Experimental study on the bond behavior of the CFRP-steel interface under the freeze–thaw cycles

2019 ◽  
Vol 54 (1) ◽  
pp. 13-29 ◽  
Author(s):  
Yu-Yang Pang ◽  
Gang Wu ◽  
Hai-Tao Wang ◽  
Zhi-Long Su ◽  
Xiao-Yuan He
Keyword(s):  
Carbon Fiber ◽  
Bond Length ◽  
Ultimate Load ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Bond Slip ◽  
Freeze Thaw ◽  
Reinforced Polymer ◽  
Carbon Fiber Reinforced

The bond–slip degradation relationship between carbon fiber-reinforced polymer and steel in a freeze–thaw environment is crucial to evaluate the long-term service performance of steel structures strengthened with carbon fiber-reinforced polymer plates. However, limited studies on the durability and long-term performance of the carbon fiber-reinforced polymer-steel-bonded interface are the major obstacle for the application of carbon fiber-reinforced polymer plates in strengthening steel structures. This paper reports an experimental study to investigate the effects of the carbon fiber-reinforced polymer bond length and the freeze–thaw cycles on the bond behavior of the carbon fiber-reinforced polymer-steel-bonded interface. The three-dimensional digital image correlation technique is applied to obtain displacements and strains on the surface of the single-shear specimen. The experimental results present herein include the failure mode, the ultimate load, the carbon fiber-reinforced polymer strain distribution, the displacement distribution, and the bond–slip relationship. The results show that the ultimate load increases with increasing bond length until a certain bond length value is reached, after which the ultimate load remained approximately constant, and the ultimate loads of carbon fiber-reinforced polymer-steel interface decrease gradually under freeze–thaw cycles. The bond–slip parameters degradation models are proposed, and the bond–slip degradation relationship under the freeze–thaw cycles is established. Finally, the bond–slip degradation relationship is confirmed through comparisons with the experimental results.

scholarly journals Experimental Investigation of the Fatigue Behavior of Basalt Fiber Reinforced Polymer Grid-Concrete Interface

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Bo Wen ◽  
Chunfeng Wan ◽  
Lin Liu ◽  
Da Fang ◽  
Caiqian Yang
Keyword(s):  
Failure Modes ◽  
Fatigue Behavior ◽  
Basalt Fiber ◽  
Fiber Reinforced Polymer ◽  
Test Results ◽  
Fiber Reinforced ◽  
Loading Level ◽  
Reinforced Polymer ◽  
Concrete Interface ◽  
Basalt Fiber Reinforced Polymer

Fatigue behavior is an important factor for mechanical analysis of concrete members reinforced by basalt fiber reinforced polymer (BFRP) grid and polymer cement mortar (PCM) and plays a critical role in ensuring the safety of reinforced concrete bridges and other structures. In this study, on the basis of the static loading test results of concrete specimens reinforced by BFRP grid and PCM, a series of fatigue tests with different loading levels were conducted on interfaces between BFRP grid and concrete to investigate the fatigue behavior of BFRP grid-concrete interfaces. The test results indicate that with high loading level, the fatigue failure mode of interface is interfacial peeling failure while it transforms to the fatigue fracture of the BFRP grid under low loading level. The fatigue life (S-N) curves of BFRP grid-concrete interface are obtained and fitted in stages according to different failure modes, and the critical point of the two failure modes is pointed out. The relative slip evolution of interface during fatigue is further revealed in different stages with two failure modes, and the law of interface strain is studied with the increase of fatigue times. The relation of effective bonding length of interface and fatigue times is also described.

scholarly journals Experimental Study on Bond Performance of Carbon- and Glass-Fiber Reinforced Polymer (CFRP/GFRP) Bars and Steel Strands to Concrete

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1268
Author(s):  
Jun Zhao ◽  
Xin Luo ◽  
Zike Wang ◽  
Shuaikai Feng ◽  
Xinglong Gong ◽  
...  
Keyword(s):  
Bond Strength ◽  
Bond Length ◽  
Retention Rate ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Bond Performance ◽  
Gfrp Bars ◽  
Reinforced Polymer ◽  
Gfrp Bar ◽  
Strength Retention

FRP bars and steel strands are widely used in civil engineering. In this study, three different types of high-strength reinforcement materials, carbon fiber reinforced polymer (CFRP) bar, glass fiber reinforced polymer (GFRP) bar, and steel strand, were investigated for their interfacial bond performance with concrete. A total of 90 sets of specimens were conducted to analyze the effects of various parameters such as the diameter of reinforcement, bond length, the grade of concrete and stirrup on the bond strength and residual bond strength. The results show that CFRP bars possess a higher bond strength retention rate than steel bars in the residual section. In addition, with the increase in bond length and diameter of the CFRP bar, the residual bond strength decreases, and the bond strength retention rate decreases. Furthermore, the bond strength retention rate of GFRP bars was found to be higher than that of CFRP bars. With the increase in grade of concrete, the bond strength and residual bond strength between GFRP bars and concrete increases, but the bond strength retention rate decreases. With an increase in bond length and diameter of the GFRP bar, the bond strength starts to decrease. Further, stirrup can also increase the bond strength and reduce the slip at the free end of GFRP bars. Moreover, the bond strength retention rate of the steel strand was found to be lower than CFRP and GFRP bar.

Experimental study and modeling of bond of carbon-fiber-reinforced polymer grids to polymer mortar at room and elevated temperatures

2020 ◽  
Vol 23 (8) ◽  
pp. 1644-1655
Author(s):  
Zongquan Liu ◽  
Qingrui Yue ◽  
Rong Li ◽  
Xiaobing Chen
Keyword(s):  
Carbon Fiber ◽  
Elevated Temperatures ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Bond Slip ◽  
Pull Out ◽  
Reinforced Polymer ◽  
Polymer Mortar ◽  
Carbon Fiber Reinforced

Carbon-fiber-reinforced polymer grids encased with polymer mortar have received much attention lately as an effective technology for strengthening concrete structures. The objective of this study was to investigate the bond-slip behavior of carbon-fiber-reinforced polymer grids to polymer mortar at room and elevated temperatures. First, 20 pull-out specimens were tested at room temperature of 20°C, and the investigated parameters included the type of carbon-fiber-reinforced polymer grids, the embedment length of longitudinal bar, and the transverse bar length. Based on the experimental results, a two-branch bond-slip model at room temperature was proposed, with the characteristic bond stress and the corresponding slip determined by the regression analysis of test data. Second, 24 pull-out specimens were tested at elevated temperatures over a range of 20°C–300°C, and the investigated parameters included the type of carbon-fiber-reinforced polymer grids and the testing temperature. Based on the experimental results, a bond-slip model at elevated temperatures was further proposed by modeling the temperature-dependent reduction factors. The two proposed bond-slip models will be particularly useful in the theoretical analysis of structures with carbon-fiber-reinforced polymer grids and polymer mortar strengthening system under both room and elevated temperatures.

scholarly journals Bond-Slip Behavior of Basalt Fiber Reinforced Polymer Bar in Concrete Subjected to Simulated Marine Environment: Effects of BFRP Bar Size, Corrosion Age, and Concrete Strength

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Yongmin Yang ◽  
Zhaoheng Li ◽  
Tongsheng Zhang ◽  
Jiangxiong Wei ◽  
Qijun Yu
Keyword(s):  
Marine Environment ◽  
Concrete Strength ◽  
Concrete Structures ◽  
Basalt Fiber ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Bond Slip ◽  
Reinforced Polymer ◽  
Superior Corrosion Resistance ◽  
Basalt Fiber Reinforced Polymer

Basalt Fiber Reinforced Polymer (BFRP) bars have bright potential application in concrete structures subjected to marine environment due to their superior corrosion resistance. Available literatures mainly focused on the mechanical properties of BFRP concrete structures, while the bond-slip behavior of BFRP bars, which is a key factor influencing the safety and service life of ocean concrete structures, has not been clarified yet. In this paper, effects of BFRP bars size, corrosion age, and concrete strength on the bond-slip behavior of BFRP bars in concrete cured in artificial seawater were investigated, and then an improved Bertero, Popov, and Eligehausen (BPE) model was employed to describe the bond-slip behavior of BFRP bars in concrete. The results indicated that the maximum bond stress and corresponding slip decreased gradually with the increase of corrosion age and size of BFRP bars, and ultimate slip also decreased sharply. The ascending segment of bond-slip curve tends to be more rigid and the descending segment tends to be softer after corrosion. A horizontal end in bond-slip curve indicates that the friction between BFRP bars and concrete decreased sharply.

scholarly journals Experimental Study on Mechanical Properties of Interface between Basalt Fiber-Reinforced Polymer/Glass Fiber-Reinforced Polymer Composite Cement Plate and Concrete

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Lifeng Zhang ◽  
Hui Liu ◽  
Wenqiang Li ◽  
Hangjun Liu ◽  
Xuehui An ◽  
...  
Keyword(s):  
Shear Strength ◽  
Failure Modes ◽  
Shear Failure ◽  
Concrete Strength ◽  
Concrete Block ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Bond Slip ◽  
Reinforced Polymer ◽  
Composite Samples

The bonding behaviors of the plate-concrete interface of a composite structure consisting of a concrete block in the middle and two cement plates at both sides play a key role in its overall mechanical performance. In this paper, the authors conduct 3 groups of push-out shear tests on a total of 39 composite samples to assess the bonding performance. The influence of the FRP cement plates, the concrete strength, and the ribs installed in the cement plate on the interfacial shear strength, the relative bond-slip, strain, and the failure modes of the composite samples is recorded and analyzed. The results show that (1) the shear strength and bond-slip performance of the interface are largely improved if the GFRP/BRRP cement plates are used; (2) shear strength of the interface increases with the concrete strength, while the deformation behaviors show no significant improvement; (3) an inclusion of the ribs to the interface enhances the shear strength and shear stiffness but decreases the maximum relative slip at failure; (4) most of the samples present the shear failures along the interface; however, the bending shear failure prior to the interface shear failure is also observed on the concrete block for low concrete strength samples and the samples with ribs; and (5) regression method is used to develop a constitutive model of the stress-slip at the interface to describe the relationship between the shear strength with the cement plates, the concrete strength, and ribs.

scholarly journals PREDICTIVE MODEL TO THE BOND STRENGTH OF FRP-TO-CONCRETE UNDER DIRECT PULLOUT USING GENE EXPRESSION PROGRAMMING

2019 ◽  
Vol 25 (8) ◽  
pp. 773-784 ◽  
Author(s):  
Yasmin Murad ◽  
Ahmed Ashteyat ◽  
Rozan Hunaifat
Keyword(s):  
Gene Expression ◽  
Tensile Strength ◽  
Bond Strength ◽  
Gene Expression Programming ◽  
Fiber Reinforced Polymer ◽  
Analytical Models ◽  
Maximum Aggregate Size ◽  
Fiber Reinforced ◽  
Pull Out ◽  
Reinforced Polymer

Gene expression programming (GEP) is used in this research to develop an empirical model that predicts the bond strength between the concrete surface and carbon fiber reinforced polymer (CFRP) sheets under direct pull out. Therefore, a large and reliable database containing 770 test specimens is collected from the literature. The gene expression programming model is developed using eight parameters that predominantly control the bond strength. These parameters are concrete compressive strength, maximum aggregate size, fiber reinforced polymer (FRP) tensile strength, FRP thickness, FRP modulus of elasticity, adhesive tensile strength, FRP length, and FRP width. The model is validated using the experimental results and a statistical assessment is implemented to evaluate the performance of the proposed GEP model. Furthermore, the predicted bond results, obtained using the GEP model, are compared to the results obtained from several analytical models available in the literature and a parametric study is conducted to further ensure the consistency of the model by checking the trends between the input parameters and the predicted bond strength. The proposed model can reasonably predict the bond strength that is most fitting to the experimental database compared to the analytical models and the trends of the GEP model are in agreement with the overall trends of the analytical models and experimental tests.

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