Predicting pull-out behaviour of 4D/5D hooked end fibres embedded in normal-high strength concrete

2018 ◽  
Vol 172 ◽  
pp. 967-980 ◽  
Author(s):  
Sadoon Abdallah ◽  
Mizi Fan ◽  
David W.A. Rees
Keyword(s):  
High Strength Concrete ◽  
High Strength ◽  
Strength Concrete ◽  
Pull Out ◽  
Hooked End Fibres

Bond behavior of high strength concrete under reversed pull-out cyclic loading

2002 ◽  
Vol 29 (2) ◽  
pp. 191-200 ◽  
Author(s):  
M Alavi-Fard ◽  
H Marzouk
Keyword(s):  
Cyclic Loading ◽  
Bond Strength ◽  
High Strength Concrete ◽  
Concrete Strength ◽  
High Strength ◽  
Displacement Curve ◽  
Bond Slip ◽  
Strength Concrete ◽  
Pull Out ◽  
Normal Strength

Structures located in seismic zones require significant ductility. It is necessary to examine the bond slip characteristics of high strength concrete under cyclic loading. The cyclic bond of high strength concrete is investigated under different parameters, including load history, confining reinforcement, bar diameter, concrete strength, and the rate of pull out. The bond strength, cracking, and deformation are highly dependent on the bond slip behavior between the rebar and the concrete under cyclic loading. The results of cyclic testing indicate that an increase in cyclic displacement will lead to more severe bond damage. The slope of the bond stress – displacement curve can describe the influence of the rate of loading on the bond strength in a cyclic test. Specimens with steel confinement sustained a greater number of cycles than the specimens without steel confinement. It has been found that the maximum bond strength increases with an increase in concrete strength. Cyclic loading does not affect the bond strength of high strength concrete as long as the cyclic slip is less than the maximum slip for monotonic loading. The behavior of high strength concrete under a cyclic load is slightly different from that of normal strength concrete.Key words: bond, high strength, cyclic loading, bar spacing, loading rate, failure mechanism.

Tensile behavior of stud connectors in high strength concrete

2021 ◽  
pp. 136943322110297
Author(s):  
Fuhai Li ◽  
Hao Gao ◽  
Yilin Jiang ◽  
Tao Wen ◽  
Yulin Zhan ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Failure Mode ◽  
High Strength Concrete ◽  
Composite Structures ◽  
Prediction Models ◽  
High Strength ◽  
Normal Concrete ◽  
Strength Concrete ◽  
Pull Out ◽  
Lower Ratio

Stud connectors are commonly used in steel-concrete composite structures. As high strength concrete (HSC) will be applied in the construction of a composite structure, it is needed to study the performance of stud connectors in HSC. In this study, tension (pull-out) tests were conducted on the studs with different combinations of diameters- d(13, 16, and 19 mm) and effective embedment depths- h ef (40, 60, and 80 mm) in HSC with a 28-day compressive strength of 88 MPa. Based on the experimental results, the concrete breakout failure mode dominates and only the scenario with the smallest diameter and largest h ef is controlled by steel failure mode. Because of high strength, the steel failure occurs at smaller h ef/ d in HSC than normal concrete. In the concrete breakout failure mode, brittle load–displacement behaviors are presented and the angle of the breakout cone ranges from 30∼35°, which is close to the concrete capacity design (CCD) method. Also, the ultimate tensile strength ( N u), stiffness, and pre-peak ductility are dependent on h ef and diameter . The existing prediction models (CCD method and variable angle cone method) both overestimate the N u in HSC, which is due to its lower ratio tensile/compressive strength than normal concrete. Considering the mechanism of how the breakout cone is formed, a modified reduced_CCD method is proposed for predicting N u of studs in HSC.

Evaluation of Bond Strength between Steel Fiber Reinforced Ultra-High Strength Concrete and Rebar

2015 ◽  
Vol 665 ◽  
pp. 41-44
Author(s):  
B.I. Bae ◽  
Hyun Ki Choi ◽  
Chang Sik Choi
Keyword(s):  
Bond Strength ◽  
High Strength Concrete ◽  
Steel Fiber ◽  
High Strength ◽  
Fiber Reinforced ◽  
Strength Concrete ◽  
Pull Out ◽  
Reinforced Concrete Member ◽  
Significant Difference ◽  
Cover Thickness

In order to design reinforced concrete member using steel fiber ultra high strength concrete, current structural design methods should be re-evaluated because it has significant difference in material characteristics compared with normal concrete. In this study, bond strength of steel fiber reinforced ultra-high strength concrete was evaluated. For this purpose, direct pull out test specimens were constructed with variables of cover thickness, compressive strength of matrix and fiber inclusion ratio. According to the test, bond strength were sensitively varied with cover thickness and fiber inclusion. Because bond strength was determined by tensile strength of concrete. Comparing test results with theoretical methods suggested by Tepfers, specimens without steel fiber show good agreement with analytical method, because this method were based on elasticity. And other empirical equations were evaluated with other previous researches.

scholarly journals Effect of Internal Curing with Superabsorbent Polymers on Bond Behavior of High-Strength Concrete

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Xiao Lei ◽  
Rui Wang ◽  
Hanwan Jiang ◽  
Faxiang Xie ◽  
Yanni Bao
Keyword(s):  
Bond Strength ◽  
High Strength Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Internal Curing ◽  
Superabsorbent Polymers ◽  
Strength Concrete ◽  
Bond Performance ◽  
Pull Out

High-strength concrete (HSC) is widely used in engineering due to its high strength and durability. However, because of its low water-to-cement ratio, external curing water hardly enters the dense internal structure of HSC so that high self-desiccation shrinkage often takes place. As a result, superabsorbent polymers (SAP) are added as an internal curing material to effectively reduce the shrinkage of high-performance concrete. Meanwhile, the bond performance between reinforcing steel and SAP HSC concrete remains unknown. In this paper, the bond performance of HSC mixed with SAP is studied by pull-out tests, and the results were obtained as follows: (1) the bond strength of HSC mixed with SAP increased first and then decreased with the increase of SAP content; (2) the slip at ultimate bond strength of HSC with SAP decreased with the increase of compressive strength; (3) a prediction model of the stress-slip relationship between steel rebars and HSC was established.

Bond Strength Of Deformed Bars and Steel Fibers in High Strength Concrete

1987 ◽  
Vol 114 ◽  
Author(s):  
Methi Wecluat ◽  
Schboon Chimamphant
Keyword(s):  
Compressive Strength ◽  
Bond Strength ◽  
High Strength Concrete ◽  
High Strength ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Fiber Reinforced ◽  
Strength Concrete ◽  
Pull Out ◽  
Deformed Bar

ABSTRACTIn recent years, the means of making high strength concrete are simple by adding microsilica, fly ash, or other types of additives. As the use of high strength concrete increases, the need to clearly understand its prcperties is essentially a necessity for engineering design. While much of the basic properties of high strength concrete such as compressive strength (fc), modulus of elasticity (Ec), and modulus of rupture (fr), etc., has been investigated and reported recently, many remain unavailable. This paper presents the bond strength characteristics of deformed bar, steel fibers, and normal aggregate in high strength concrete matrix. The compressive strength of concrete used in this study is 75–80 MPa (11,000-12,000 psi). Bond slip relationships of deformed bars of three different bar diameters were obtained from the pull-cut test. Two types of steel fiber reinforced high strength cemented composites were tested in a directtension, tapered specimen to observe the pulled-out behavior of steel fibers. Fiber reinforced concretes with fiber volume fraction of 0.5, 1.0, 1.5, and 2.0 % were compared to the unreinforced matrix. A direct-tension, dog boned specimen was used to study the bond between aggregate-matrix interface. The results from this study indicate that high strength concrete is generally more brittle, and in essence, allows less microcracking, less slippage, and less pulled-out deformation. This general trend is observed in both the deformed bar and fiber pulled-out as well as in aggregate-matrix interfacial debonding. The maximum slip of deformed bars in high strength concrete is about 0.15 mm.(0.006 in.) which is only one-tenth of that reported for normal concrete as 1.5 to 2.0 mm.(0.06–0.08 in.). A normalized pull-out stress-displacement relationship of high strength fiber reinforced concrete exhibits a unique behavior similar to those reported for normal fiber reinforced matrix.

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