Bond Stress and Development Length Calculation of CFRP Grid through Direct Pullout Test

2021 ◽  
Vol 12 (4) ◽  
pp. 66-72
Author(s):  
Dongyoung Choi ◽  
◽  
Sohyeon Heo ◽  
Yeongseok Jeong ◽  
Minho Kwon
Keyword(s):  
Pullout Test ◽  
Bond Stress ◽  
Development Length

scholarly journals Optimization of the effect of corrosion on bond behaviour between steel and concrete

2021 ◽  
Author(s):  
Zahir Aldulaymi
Keyword(s):  
Compressive Strength ◽  
Bond Strength ◽  
Laboratory Study ◽  
Crack Width ◽  
Electrochemical Corrosion ◽  
Pullout Test ◽  
Concrete Cover ◽  
Bond Stress ◽  
Chloride Ingress ◽  
Four Levels

This research program consists of laboratory study of corrosion phenomenon in reinforced concrete and further analytical study of the experimental results obtained by Amleh (2000). The laboratory study examined the influence of increasing levels of corrosion on the progressive deterioration of bond between the steel and concrete and determined the extent to which the various water to cement (w/c) ratio in concrete mixtures influence the corrosion of the steel reinforcement as well as the chloride ion penetration. The influence of corrosion on the bond characteristics of the reinforcing bars in pullout test specimens made with two different w/c ratios and two different concrete cover thicknesses were investigated using control specimens to study the effect of the concrete cover ratio and the concrete compressive strength. The two w/c ratios were 0.47 and 0.37, with two concrete cover thicknesses of 40 mm and 65 mm. Hence, the effect of w/c ratio on different parameters like rate of corrosion, compressive strength and the effect of concrete cover thickness on the corrosion rate were studied. An accelerated electrochemical corrosion procedure was used to develop four levels of corrosion including no corrosion to complete corrosion, with over 25 percent steel bar weight loss due to corrosion, with wide longitudinal cracks. This research study clearly indicated that the bond stress-slip response of the embedded bar in the pullout specimen, was adversely affected by the width of the crack, and the level of corrosion. The crack width was found to develop faster and longer in specimens with lower compressive strength and as a result the maximum bond strength in the pullout test is affected signifcantly by the number and size of cracks, and thus, the level of corrosion. For a given crack width due to corrosion, it is observed that the available bond strength is higher for larger concrete cover thicknesses than for smaller cover thicknesses. Certainly, the quality of concrete in terms of its permeability is equally important for the corrision protection. A relationship between the effect of w/c ratio on chloride ingress was developed to count for the deterioration in bond stress, and the induced current used in corroding the speciments of Amleh (2000) and of this investigation program were incorporated to consider for the lack of chloride lot content measured due to the shorter immersing time in this investigation and the high current used to force the specimens to corrode in the accelerated corrosion process.

scholarly journals Development Length of GFRP Rebar Based on Non-uniform Bond Stress

2021 ◽  
Author(s):  
Elyas Makhmalbaf ◽  
Ghani Razaqpur
Keyword(s):  
Stress Distribution ◽  
Growth Function ◽  
Test Methods ◽  
Bond Stress ◽  
Test Method ◽  
Logistic Growth ◽  
Development Length ◽  
Design Standards ◽  
Pullout Tests ◽  
Highly Nonlinear

Due to the assumption of uniform bond stress, the development length of FRP bars by design standards can be unnecessarily long and difficult to provide in practice. Hence, the bond stress distribution and required development length of a GFRP rebar is investigated. Four beam-bond specimens, two following RILEM specifications and two based on a procedure by ACI are tested to evaluate the effect of test method on bond strength. Ten pullout tests are also performed using the same bar. The two test methods yield similar results, but the ACI test is easier to perform. The bond stress distribution in the beams is highly nonlinear but in the pullout tests approaches uniformity. The actual development length is found to be 50% to 250% less than that required by the foregoing standards. Consequently, a new equation is proposed based on the logistic growth function to model the non-uniform bond stress distribution and estimate the required development length.

scholarly journals Optimization of the effect of corrosion on bond behaviour between steel and concrete

2021 ◽  
Author(s):  
Zahir Aldulaymi
Keyword(s):  
Compressive Strength ◽  
Bond Strength ◽  
Laboratory Study ◽  
Crack Width ◽  
Electrochemical Corrosion ◽  
Pullout Test ◽  
Concrete Cover ◽  
Bond Stress ◽  
Chloride Ingress ◽  
Four Levels

This research program consists of laboratory study of corrosion phenomenon in reinforced concrete and further analytical study of the experimental results obtained by Amleh (2000). The laboratory study examined the influence of increasing levels of corrosion on the progressive deterioration of bond between the steel and concrete and determined the extent to which the various water to cement (w/c) ratio in concrete mixtures influence the corrosion of the steel reinforcement as well as the chloride ion penetration. The influence of corrosion on the bond characteristics of the reinforcing bars in pullout test specimens made with two different w/c ratios and two different concrete cover thicknesses were investigated using control specimens to study the effect of the concrete cover ratio and the concrete compressive strength. The two w/c ratios were 0.47 and 0.37, with two concrete cover thicknesses of 40 mm and 65 mm. Hence, the effect of w/c ratio on different parameters like rate of corrosion, compressive strength and the effect of concrete cover thickness on the corrosion rate were studied. An accelerated electrochemical corrosion procedure was used to develop four levels of corrosion including no corrosion to complete corrosion, with over 25 percent steel bar weight loss due to corrosion, with wide longitudinal cracks. This research study clearly indicated that the bond stress-slip response of the embedded bar in the pullout specimen, was adversely affected by the width of the crack, and the level of corrosion. The crack width was found to develop faster and longer in specimens with lower compressive strength and as a result the maximum bond strength in the pullout test is affected signifcantly by the number and size of cracks, and thus, the level of corrosion. For a given crack width due to corrosion, it is observed that the available bond strength is higher for larger concrete cover thicknesses than for smaller cover thicknesses. Certainly, the quality of concrete in terms of its permeability is equally important for the corrision protection. A relationship between the effect of w/c ratio on chloride ingress was developed to count for the deterioration in bond stress, and the induced current used in corroding the speciments of Amleh (2000) and of this investigation program were incorporated to consider for the lack of chloride lot content measured due to the shorter immersing time in this investigation and the high current used to force the specimens to corrode in the accelerated corrosion process.

Development Length of GFRP Rebars Based on Pullout Test

2007 ◽  
Vol 19 (3) ◽  
pp. 323-331 ◽  
Author(s):  
Dong-Uk Choi ◽  
Sang-Su Ha ◽  
Chang-Ho Lee
Keyword(s):  
Pullout Test ◽  
Development Length ◽  
Gfrp Rebars

Experimental Study on Bonding Mechanism between Corroded Bolts and Grout

2007 ◽  
Vol 345-346 ◽  
pp. 1063-1066
Author(s):  
Ning Xia ◽  
Mao Sen Cao ◽  
Qing Wen Ren
Keyword(s):  
Experimental Study ◽  
Stress Distribution ◽  
Mechanical Behavior ◽  
Corrosion Product ◽  
Pullout Test ◽  
Bond Stress ◽  
Experimental Results ◽  
Bonding Mechanism ◽  
The Relationship ◽  
Front Section

In this study, an experiment program is presented to study the bonding mechanism between corroded bolts and grout and in particular the influence on bonding behavior in terms of different corrosion sections along anchor. With respect to four groups of manufactured bolt specimens, the noncorroded and the corroded, respectively, on the front, middle and rear section along anchor, a pullout test is conducted to reveal the relationship between load and loading-end slip and to investigate the bond-stress distribution characterization along full anchor. Experimental results show that corrosion product, acting as lubricating effect at the interface between bolts and grout, can result in the degradation of bonding mechanical behavior. Meanwhile, corrosion on different sections along anchor has a different effect on the anchorage capacity of bolts. Especially, corrosion on the front section induces the greatest decrease of anchorage capacity of bolts. Thus, it is concluded that the front section along anchor is the key region affecting the bonding mechanical behavior between bolts and grout.

Development Length of Headed Bar Based on Nonuniform Bond Stress Distribution

2019 ◽  
Vol 116 (2) ◽  
Author(s):  
Hyeon-Jong Hwang ◽  
Hong-Gun Park ◽  
Wei-Jian Yi
Keyword(s):  
Stress Distribution ◽  
Bond Stress ◽  
Development Length

scholarly journals THE BOND STRENGTH OF STEEL BAR BASE ON RIB GEOMETRY BAR IN PULLOUT TEST

2021 ◽  
Vol 30 (1) ◽  
Author(s):  
Anis Rosyidah ◽  
Johannes Adhijoso Tjondro ◽  
I Ketut Sucita
Keyword(s):  
Bond Strength ◽  
Pullout Test ◽  
Bond Stress ◽  
Failure Pattern ◽  
Bond Index ◽  
Steel Bar ◽  
Study Results ◽  
Concrete Cube

This experiment's objective is to prove that the reinforcing rib's form contributes to its bond strength. The specimen is the concrete cubes measuring 150 × 150 × 150 mm; bar installed in the center of the concrete cube. Bars use 13, 16, and 19 mm diameters. For comparison, the experiment was also carried out on plain reinforcement diameter with 12 mm, 16 mm, and 19 mm. Concrete compression is fc' 34 MPa. The pullout test was also performed to increase the load in stages at a 200 kg/minute speed. Loading stopped if the reinforcement yielded, split concrete, or slipped bar. The experiment uses ASTM standards ASTM C234-91a. The study results are the bond strength on reinforcement with the surrounding concrete. Bond strength in the plain bar is lower than deformed. The reinforcement of steep rib compared to fishbone bond strength values incline to be the same. The ratio of the bond strength of plain compared to deformed is 15% - 18%. The bond index of the steep rib and fishbone rib between 0.11 - 0.16 so that the bond stress obtained is also relatively the same. The failure pattern that occurs is determined based on the bond stress-slip graph. There are two types of collapse in this experiment, namely pullout and splitting damage. The failure of each specimen based on the diameter and shape of the rib varies greatly. The splitting damage is seen visually only in the specimen of the D19 fishbone rib.

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