Beam Test Research on Bond Behavior between Steel Bar and Concrete in Salt-Frost Environment

2011 ◽  
Vol 261-263 ◽  
pp. 50-55
Author(s):  
Gang Xu ◽  
Tian Cheng Ai ◽  
Qing Wang ◽  
Jiang Bo Huang
Keyword(s):  
Bond Strength ◽  
Concrete Beam ◽  
Saline Solution ◽  
Freezing And Thawing ◽  
Bond Failure ◽  
Actual Structure ◽  
Bond Behavior ◽  
Steel Bar ◽  
Bond Property ◽  
Freezing And Thawing Cycles

Salt-frost action is one of the main causes that induced the decrease of force resistance behavior of concrete structure in cold areas. By the freezing and thawing cycles of 0, 50, 100 and 200 times for the reinforcement concrete beam specimens in saline solution, the effects of freezing and thawing cycles on the bond behavior between steel bar and concrete are studied. The results show that: with the increase of freezing and thawing cycles, the bond strength and the bond stiffness trend to degenerate. The co-operating capacity between steel bar and concrete falls down. The ductility of the specimens reduces, and the bond failure presents brittle. The degradation speed of bond strength after salt-frosting is relevant to the size and stirrup ratio of specimens, the larger the specimen’s size is, and the higher the stirrup ratio is, The stronger the capacity of resisting freezing-thawing cycle is, the more slowly the bond property degenerate, the study using small specimens will probably underestimate the frost resistance of actual structure.

scholarly journals An Experimental Study of Bond Behavior of Micro Steel Fibers Added Self-compacting Concrete with Steel Reinforcement

2020 ◽  
Author(s):  
Abdul Salam ◽  
Shah Room ◽  
Shahid Iqbal ◽  
Khalid Mahmood ◽  
Qaiser Iqbal
Keyword(s):  
Bond Strength ◽  
Steel Fibers ◽  
Self Compacting Concrete ◽  
Bond Failure ◽  
Maximum Increase ◽  
Bond Behavior ◽  
Micro Cracks ◽  
Steel Bar ◽  
Experimental Values ◽  
Major Emphasis

The obstruction offered by the surrounding concrete to the pulling out of embedded steel bar is known as bond strength. Steel fibers addition to concrete improves its bond strength by arresting the cracks due to their bridging effect. Bond failure occurs when cracks in the surrounding concrete initiates, providing enough space for bar to be pulled-out. Micro steel fibers efficiently control the formation of micro cracks and may improve bond strength to a greater extent compared to the longer steel fibers. However, it reduces the workability of concrete which is of greater importance in case of self-compacting concrete (SCC). Reduction of workability is less pronounced when straight micro steel fibers are used due to their shorter lengths and straight geometry. Thus, different amount of straight micro steel fibers (0.25 %, 0.5 %, 0.75 %) were incorporated in to SCC to investigate their fresh and mechanical properties with major emphasis on the bond strength. Results indicate that steel fibers addition to SCC improve the splitting tensile strength and bond strength significantly with a maximum increase of 33.5 % and 54.9 % respectively with 0.75 % fibers addition. An equation is proposed for the calculation of bond strength with micro steel fibers addition to SCC with a maximum variation of 4 % to those of experimental values.

scholarly journals Effect of Coating Thickness on Bond Behaviors of Polymer Cement Coated Plain Steel Bar with Concrete and Finite Element Modeling

2016 ◽  
Vol 10 (1) ◽  
pp. 571-577 ◽  
Author(s):  
Xiong Yuanliang ◽  
Wang Kunrong ◽  
Liu Zhiyong ◽  
Yang Zhengguang
Keyword(s):  
Finite Element ◽  
Bond Strength ◽  
Coating Thickness ◽  
Failure Modes ◽  
Bond Behavior ◽  
Finite Element Software ◽  
Pullout Tests ◽  
Steel Bar ◽  
Contact Surfaces ◽  
Hot Rolled

The pullout tests were carried out to investigate the effect of coating thickness on bond behavior (failure modes, bond strength, bond stress slip curves) between hot rolled plain steel bar (HPB) coated with polymer cement based coating and concrete. The results indicated the failure mode of the specimens is pullout. Suitable coating thickness could enhance the bond strength of steel bar embedded with concrete. By using contact surfaces with cohesive behavior in finite element software, the slip between coated plain steel bar and concrete can be realized. The results of numerical simulation are close to that of experiments, indicating that the model using contact surfaces with cohesive behavior can reasonably predict the results of pullout tests of HPB in concrete.

scholarly journals Finite element analysis on the bond behavior of steel bar in salt–frost-damaged recycled coarse aggregate concrete

2021 ◽  
Vol 60 (1) ◽  
pp. 853-861
Author(s):  
Tian Su ◽  
Ting Wang ◽  
Haihe Yi ◽  
Rui Zheng ◽  
Yizhe Liu ◽  
...  
Keyword(s):  
Bond Strength ◽  
Concrete Cover ◽  
Bond Slip ◽  
Bond Behavior ◽  
Steel Bar ◽  
Calculation Results ◽  
Cover Thickness ◽  
Bar Diameter ◽  
Good Agreement ◽  
Ultimate Bond Strength

Abstract In this article, the ABAQUS finite element software is used to simulate the bond behavior of the steel bar in salt–frost-damaged recycled coarse aggregate concrete, and the influence of the steel bar diameter and the concrete cover thickness on the bond strength is investigated. The result shows that the calculated bond–slip curve is in good agreement with the experimental bond–slip curve; the mean value of the ratio of the calculation results of ultimate bond strength to the experiment results of ultimate bond strength is 1.035, the standard deviation is 0.0165, and the coefficient of variation is 0.0159, which proves that the calculation results of the ultimate bond strength are in good agreement with the experimental results; with the increase of steel bar diameter and the concrete cover thickness, the ultimate bonding strength of RAC and steel increases; the calculation formulas for the ultimate bond strength of specimens with different steel bar diameters (concrete cover thickness) after different salt–frost cycles are obtained.

scholarly journals Fatigue Characteristics of Prestressed Concrete Beam under Freezing and Thawing Cycles

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Yuanxun Zheng ◽  
Lei Yang ◽  
Pan Guo ◽  
Peibing Yang
Keyword(s):  
Fatigue Life ◽  
Prestressed Concrete ◽  
Life Prediction ◽  
Concrete Beam ◽  
Concrete Beams ◽  
Freezing And Thawing ◽  
Freeze Thaw ◽  
Prestressed Concrete Beam ◽  
Fatigue Characteristics ◽  
Freezing And Thawing Cycles

In order to reveal the influence of freezing and thawing on fatigue properties of the prestressed concrete beam, a kind of novel freeze-thaw test method for large concrete structure components was proposed, and the freeze-thaw experiments and fatigue failure test of prestressed concrete hollow beams were performed in this paper. Firstly, the compressive strength and dynamic elastic modulus of standard specimens subjected to different numbers of freeze-thaw cycles (0, 50, 75, and 100) were determined. Then, the static and dynamic experiments were performed for prestressed concrete beams under different freeze-thaw cycles. Depending on the static failure test results, the fatigue load for the prestressed concrete beam model was carried out, the fatigue tests for prestressed concrete beam under freezing and thawing cycles were done, and the influence of fatigue loading times on dynamic and static characteristics of prestressed concrete beam was also studied. Finally, the relation between fatigue characteristics and numbers of freeze-thaw cycles was established, and the fatigue life prediction formulas of prestressed concrete beams under freeze-thaw cycles were developed. The research shows that the freezing and thawing cycles had obvious influence on fatigue life, and the freezing and thawing cycles should be taken into account for life prediction and quality evaluation of prestressed concrete beams.

scholarly journals A study of the bond behavior of FRP bars in MPC seawater concrete

2020 ◽  
pp. 136943322095681
Author(s):  
Wen Sun ◽  
Yu Zheng ◽  
Linzhu Zhou ◽  
Jiapeng Song ◽  
Yun Bai
Keyword(s):  
Bond Strength ◽  
Potassium Phosphate ◽  
Fiber Reinforced Polymer ◽  
Reinforcing Bars ◽  
Bond Behavior ◽  
Reinforced Polymer ◽  
Steel Bar ◽  
Gfrp Bar ◽  
Frp Bar ◽  
Frp Bars

Using magnesium potassium phosphate cement (MPC) and fiber-reinforced polymer (FRP) bar to produce reinforced concrete can overcome the durability problems facing conventional steel reinforced PC concrete. In addition, FRP bar reinforced MPC concrete can also mitigate the CO2 emission issues caused by Portland cement (PC) production and the shortage of natural resources such as virgin aggregates and freshwater. This paper, therefore, is aimed at investigating the bond behavior of the FRP bars in MPC seawater concrete. The direct pullout tests were conducted with a steel bar, BFRP bar, and GFRP bar embedded into different concretes. The effects of reinforcing bars, type of concrete and mixing water on the bond behavior of FRP and steel bars were investigated and discussed. The results showed that the MPC concrete increases the bond strength of BFRP and GFRP bars by 51.06% and 24.42%, respectively, compared with that in PC concrete. Using seawater in MPC concrete can enhance the bond strength of GFRP bar by 13.75%. The damage interface of the FRP bar -MPC is more severe than that of PC with a complete rupture of the FRP ribs and peeling-off of the resin compared to that in steel reinforced MPC specimens. Moreover, the bond stress-slip models were developed to describe the bond behavior of MPC-FRP specimen, and the analytical results match well with the experimental data. In conclusion, the FRP bars showed better bond behavior in the MPC seawater concrete than that in the PC counterparts.

Effect of Elevated Temperature on Bond Strength of Concrete

2019 ◽  
Vol 972 ◽  
pp. 26-33
Author(s):  
Muhammad Harunur Rashid ◽  
Md. Maruf Molla ◽  
Imam Muhammad Taki
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperature ◽  
Bond Strength ◽  
Elevated Temperatures ◽  
Reinforced Concrete Structure ◽  
Bond Behavior ◽  
Pull Out ◽  
Steel Bar ◽  
Residual Capacity ◽  
Water Curing

In the case of exposure of reinforced concrete structure to accidental fire, an assessment of its residual capacity is needed. Bond strength of concrete was observed under elevated temperatures (150°, 250°, 350° and 500°C) in this study. Cylindrical specimens were prepared for pull-out tests to find out the bond behavior and to observe the mechanical properties of concrete. All the specimens were 100 mm diameter and 200 mm height. The pull-out specimens contain a 10 mm steel bar at its center. The specimens were tested at 52 days age following a 28 days water curing. Samples were preheated for 3 hours at 100°C temperature and then put into the furnace for 1 hour at the target temperature. Samples were tested before preheating as controlled specimens. In case of mechanical properties and the bond strength of concrete, there were no remarkable changes due to elevated temperature up to 150°C. However, the mechanical properties and bond strength were decreased gradually after 150°C temperature. Maximum reduction of bond strength observed was 52.13% and 49.8% at 500°C for testing within 1 hour and after 24 hours of heating respectively when compared to the controlled specimens. Bond strength was found to reduce at a greater rate than compressive strength due to the elevated temperature.

Experimental investigation on bond strength between BFRP bars and concrete under freeze-thaw cycles

2021 ◽  
pp. 002072092199659
Author(s):  
Xiao-Yong Wu ◽  
Kai Zhou ◽  
Xiao-Lu Yuan ◽  
Yong-Shuai Zhu ◽  
Pei Fan ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Bond Strength ◽  
Concrete Strength ◽  
Freezing And Thawing ◽  
Freeze Thaw ◽  
Thawing Cycle ◽  
Pull Out ◽  
The Times ◽  
Freezing And Thawing Cycles ◽  
Ultimate Bond Strength

To investigate the bond strength between BFRP bars and concrete under freezing and thawing cycles, a total of 36 specimens for freezing and thawing cycles tests and center pull-out tests were carried out with different times of freezing and thawing cycles (0, 10, 20, and 40 times) and different concrete strength grades (C30, C35, and C40). The results of this study showed that the specimens without freezing and thawing cycle (0 times) and specimens of C30 with freeze-thaw for 40 times were pulled out, and the remaining specimens were split. With the increase of the concrete strength grade, the debonding strength increases gradually and the ultimate bond strength does not increase in proportion. The debonding strength of BFRP bars and concrete decreases gradually with the times of freezing and thawing cycles. The ultimate bond strength and peak slip indicated a trend of increasing and then decreasing with the increasing times of freezing and thawing, while the peak slip of specimens of C30 with 40 times freeze-thaw increases slightly.

scholarly journals The Effects of Prophylactic Ozone Pretreatment of Enamel on Shear Bond Strength of Orthodontic Brackets Bonded with Total or Self-Etch Adhesive Systems

2010 ◽  
Vol 04 (04) ◽  
pp. 367-373 ◽  
Author(s):  
Sevi Burcak Cehreli ◽  
Asli Guzey ◽  
Neslihan Arhun ◽  
Alev Cetinsahin ◽  
Bahtiyar Unver
Keyword(s):  
Bond Strength ◽  
Shear Bond Strength ◽  
Orthophosphoric Acid ◽  
Ozone Treatment ◽  
Bond Failure ◽  
Group 4 ◽  
Group 3 ◽  
Group 2 ◽  
Self Etch ◽  
Group 1

Objectives: The aim of this in vitro study is to determine (1) shear bond strength (SBS) of brackets bonded with self-etch and total-etch adhesive after ozone treatment (2) bond failure interface using a modified Adhesive Remnant Index (ARI).Methods: 52 premolars were randomly assigned into four groups (n=13) and received the following treatments: Group 1: 30 s Ozone (Biozonix, Ozonytron, Vehos Medikal, Ankara, Turkey) application + Transbond Plus Self-Etching Primer (SEP) (3M) + Transbond XT (3M), Group 2: Transbond Plus SEP + Transbond XT, Group 3: 30 s Ozone application + 37% orthophosphoric acid + Transbond XT Primer (3M) + Transbond XT, Group 4: 37% orthophosphoric acid + Transbond XT Primer + Transbond XT. All samples were stored in deionised water at 37oC for 24 hours. Shear debonding test was performed by applying a vertical force to the base of the bracket at a cross-head speed of 1 mm/min.Results: The mean SBS results were Group 1: 10.48 MPa; Group 2: 8.89 MPa; Group 3: 9.41 MPa; Group 4: 9.82 MPa. One-Way Variance Test revealed that the difference between the groups was not statistically significant (P=0.267). Debonded brackets were examined by an optical microscope at X16 magnification to determine the bond failure interface using a modified ARI. The results were (mean) Group 1: 2.38; Group 2: 1.31; Group 3: 3.00; Group 4: 1.92. Multiple comparisons showed that Groups 1 and 2, 2 and 3, 3 and 4 were statistically different (P=0.014, P<.001 and P=0.025).Conclusions: Ozone treatment prior to bracket bonding does not affect the shear bond strength. (Eur J Dent 2010;4:367-373)

Deformation Characteristics of Reinforced Concrete Beam-Column Joint Cores under Earthquake Loading

2003 ◽  
Vol 6 (1) ◽  
pp. 15-21 ◽  
Author(s):  
Sayed A. Attaalla ◽  
Mehran Agbabian
Keyword(s):  
Reinforced Concrete ◽  
Shear Deformation ◽  
Concrete Beam ◽  
Reinforced Concrete Beam ◽  
Reinforced Concrete Frame ◽  
Bond Failure ◽  
Strain Compatibility ◽  
Concrete Frame ◽  
Column Joint ◽  
Reinforced Concrete Frame Structures

The characteristics of the shear deformation inside the beam-column joint core of reinforced concrete frame structures subjected to seismic loading are discussed in this paper. The paper presents the formulation of an analytical model based on experimental observations. The model is intended to predict the expansions of beam-column joint core in the horizontal and vertical directions. The model describes the strain compatibility inside the joint in an average sense. Its predictions are verified utilizing experimental measurements obtained from tests conducted on beam-column connections. The model is found to adequately predict the components of shear deformation in the joint core and satisfactorily estimates the average strains in the joint hoops up to bond failure. The model may be considered as a simple, yet, important step towards analytical understanding of the sophisticated shear mechanism inside the joint and may be implemented in a controlled-deformation design technique of the joint.

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