Identification of Bond-Slip Behavior of GFRP-ECC Using Smart Aggregate Transducers

AbstractThe article describes an experimental study on the bond–slip performance between the pultruded glass fiber-reinforced polymer (GFRP) tube and the nano-CaCO3 concrete. Taking the nano-CaCO3 concrete strength and GFRP tube thickness as primary parameters, nine specimens were designed and tested to study the influence of these parameters on the bond strength of the specimens. Besides, three specimens filled with the ordinary concrete were also tested by using the push-out tests to make comparisons with the bond performance of the specimens filled with nano-CaCO3 concrete. A total of four push-out tests were conducted on each specimen. The experimental results indicate that there are two types of axial load–slip curves for each specimen in four push-out tests. Moreover, comparison of the results of the push-out tests in the same direction shows that the bond failure load of the specimen decreases with the increase in the number of push-out tests. Based on the analysis of the test results, it is shown that the bond performance between the GFRP tube and the nano-CaCO3 concrete is better than that between the GFRP tube and the ordinary concrete. Furthermore, as the nano-CaCO3 concrete strength increases, the bond strength of the specimens decreases, indicating that the concrete strength has a negative effect on the bond strength. When the nano-CaCO3 concrete strength is relatively smaller (C20), the bond strength of the specimens decreases with the increase in the thickness of the GFRP tube. However, when the nano-CaCO3 concrete strength is relatively larger (C30 and C40), the bond strength of the specimens increases as the thickness of the GFRP tube increases.

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Design and Analysis of a Novel Piezoceramic Stack-based Smart Aggregate

Sensors ◽

10.3390/s20226438 ◽

2020 ◽

Vol 20 (22) ◽

pp. 6438

Author(s):

Guangtao Lu ◽

Xin Zhu ◽

Tao Wang ◽

Zhiqiang Hao ◽

Bohai Tan

Keyword(s):

Resonance Frequency ◽

Electromechanical Coupling ◽

Structural Parameters ◽

Electromechanical Coupling Factor ◽

Coupling Factor ◽

Stress Waves ◽

Parallel Connection ◽

Smart Aggregate ◽

In Series ◽

Piezoelectric Wafers

A novel piezoceramic stack-based smart aggregate (PiSSA) with piezoceramic wafers in series or parallel connection is developed to increase the efficiency and output performance over the conventional smart aggregate with only one piezoelectric patch. Due to the improvement, PiSSA is suitable for situations where the stress waves easily attenuate. In PiSSA, the piezoelectric wafers are electrically connected in series or parallel, and three types of piezoelectric wafers with different electrode patterns are designed for easy connection. Based on the theory of piezo-elasticity, a simplified one-dimensional model is derived to study the electromechanical, transmitting and sensing performance of PiSSAs with the wafers in series and parallel connection, and the model was verified by experiments. The theoretical results reveal that the first resonance frequency of PiSSAs in series and parallel decreases as the number or thickness of the PZT wafers increases, and the first electromechanical coupling factor increases firstly and then decrease gradually as the number or thickness increases. The results also show that both the first resonance frequency and the first electromechanical coupling factor of PiSSA in series and parallel change no more than 0.87% as the Young’s modulus of the epoxy increases from 0.5 to 1.5 times 3.2 GPa, which is helpful for the fabrication of PiSSAs. In addition, the displacement output of PiSSAs in parallel is about 2.18–22.49 times that in series at 1–50 kHz, while the voltage output of PiSSAs in parallel is much less than that in parallel, which indicates that PiSSA in parallel is much more suitable for working as an actuator to excite stress waves and PiSSA in series is suitable for working as a sensor to detect the waves. All the results demonstrate that the connecting type, number and thickness of the PZT wafers should be carefully selected to increase the efficiency and output of PiSSA actuators and sensors. This study contributes to providing a method to investigate the characteristics and optimize the structural parameters of the proposed PiSSAs.

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Assessment of bond-slip behavior of hybrid fiber reinforced engineered cementitious composites (ECC) and deformed rebar via AE monitoring

Cement and Concrete Composites ◽

10.1016/j.cemconcomp.2021.103961 ◽

2021 ◽

Vol 118 ◽

pp. 103961

Author(s):

Wenchen Shan ◽

Jiepeng Liu ◽

Yao Ding ◽

Weihao Mao ◽

Yubo Jiao

Keyword(s):

Cementitious Composites ◽

Fiber Reinforced ◽

Hybrid Fiber ◽

Engineered Cementitious Composites ◽

Bond Slip

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Analytical Investigation on the Effect of Test Setup on Bond Strength

CivilEng ◽

10.3390/civileng2010002 ◽

2021 ◽

Vol 2 (1) ◽

pp. 14-34

Author(s):

Konstantinos Tsiotsias ◽

Stavroula J. Pantazopoulou

Keyword(s):

Bond Strength ◽

Pullout Test ◽

Analytical Investigation ◽

Strength Increase ◽

Confining Stress ◽

Direct Tension ◽

Bond Slip ◽

Test Setup ◽

Long Time

Experimental procedures used for the study of reinforcement to concrete bond have been hampered for a long time by inconsistencies and large differences in the obtained behavior, such as bond strength and mode of failure, depending on the specimen form and setup used in the test. Bond is controlled by the mechanics of the interface between reinforcement and concrete, and is sensitive to the influences of extraneous factors, several of which underlie, but are not accounted for, in conventional pullout test setups. To understand and illustrate the importance of specimen form and testing arrangement, a series of computational simulations are used in the present work on eight distinct variants of conventional bar pullout test setups that are used routinely in experimental literature for the characterization of bond-slip laws. The resulting bond strength increase generated by unaccounted confining stress fields that arise around the bar because of the boundary conditions of the test setup is used to classify the tests with respect to their relevance with the intended use of the results. Of the pullout setups examined, the direct tension pullout test produced the most conservative bond strength results, completely eliminating the contributions from eccentricity and passive confinement.

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Experimental and Numerical Investigation on the Steel Reinforced Grout (SRG) Composite-to-Concrete Bond

Journal of Composites Science ◽

10.3390/jcs4040182 ◽

2020 ◽

Vol 4 (4) ◽

pp. 182

Author(s):

Luciano Ombres ◽

Salvatore Verre

Keyword(s):

Bond Length ◽

Failure Modes ◽

Peak Load ◽

Element Model ◽

Test Results ◽

Shear Tests ◽

Bond Slip ◽

Bond Behavior ◽

Direct Shear Tests ◽

Inorganic Matrix

In the paper, the bond between a composite strengthening system consisting of steel textiles embedded into an inorganic matrix (steel reinforced grout, SRG) and the concrete substrate, is investigated. An experimental investigation was carried out on medium density SRG specimens; direct shear tests were conducted on 20 specimens to analyze the effect of the bond length, and the age of the composite strip on the SRG-to-concrete bond behavior. In particular, the tests were conducted considering five bond length (100, 200, 250, 330, and 450 mm), and the composite strip’s age 14th, 21st, and 28th day after the bonding. Test results in the form of peak load, failure modes and, bond-slip diagrams were presented and discussed. A finite element model developed through commercial software to replicate the behavior of SRG strips, is also proposed. The effectiveness of the proposed numerical model was validated by the comparison between its predictions and experimental results.

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Bond-slip behavior between corroded I-shaped steel and concrete in a subsea tunnel

Engineering Failure Analysis ◽

10.1016/j.engfailanal.2020.105061 ◽

2021 ◽

Vol 120 ◽

pp. 105061

Author(s):

Yiteng Zhang ◽

Mingnian Wang ◽

Li Yu ◽

Xiaohan Guo ◽

Zhuhong Wang ◽

...

Keyword(s):

Bond Slip ◽

Subsea Tunnel

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Experimental Study on Bond-Slip Constitutive Relation between CFL and Concrete

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.302.359 ◽

2013 ◽

Vol 302 ◽

pp. 359-364

Author(s):

X.H. Zheng ◽

P.Y. Huang ◽

X.Y. Guo ◽

Q. Han

Keyword(s):

Constitutive Relation ◽

Displacement Sensor ◽

Key Factors ◽

Bond Slip ◽

Factors Affecting ◽

Slip Mechanism ◽

Double Shear ◽

Carbon Fiber Laminate ◽

Externally Bonded ◽

Longitudinal Strains

Externally bonded reinforcing technique with fiber reinforced polymer (FRP) has been widely used in civil engineering. The performance of the interface between FRP and concrete is one of the key factors affecting the behavior of the strengthened structures. This paper presents a detailed study on the bond-slip mechanism between carbon fiber laminate (CFL) and concrete based on double-shear tests. 8 specimens with different bonded length and width of CFL were tested under static loading. Strain gauges along the CFL face and displacement sensor were used to measure longitudinal strains and slip of the interface. The bond-slip constitutive relation of the interface between CFL and concrete was analyzed with the testing results. Compared with four different bond-slip models, a shear stress-slip model was proposed based on the experimental data.

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