• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.197-200
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• 2005

This paper presents an analytical model for evaluation of Tension Stiffening Effect by actual Bond-Slip relationships between the reinforcement and the surrounding concrete. The presence of longitudinal splitting cracks was found to significantly after the tension stiffening. The model is applied to the longitudinal splittings cracks and derived to Tension stiffening model. The predicted values are shown to be in good agreement with the experimentally measured data.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.519-526
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• 1997

The purpose of this study is to develop the analytical model for the reinforcement bar connection in group-filled steel pipe sleeve, which consists of beam elements for the reinforcement bar and shell elements for the sleeve and the mortar and spring elements for the bond stress-slip relationship. In the reinforcement bar connection using grout-filled steel pipe sleeve, the major variables are the bond stiffness between reinforcement bar and mortar($K_1$) and between sleeve and mortar($K_2$). It is nearly difficult to predict the exact bond stiffness with the experimental results. Therefore, The linearly elastic analyses using ABAQUS, FEM package show the validity of the mathematical equations for the bond stiffness and the choice of material elements in this paper. To predict the behaviour between yield and ultimate tensile strength, the nonlinear analyses must be performed henceforth.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.537-542
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• 2002

The social trouble to the durability of concrete rises recently because the embedded rebar corrosion influences concrete structures to deteriorate structural capacity. And also, the rebar corrosion causes crack of concrete, decrease of steel section and separation of covering concrete. In the result, the bond strength of concrete and embedded rebar decreases, which causes deterioration of the structure behavior in reinforced concrete. In this study, the relation of bond strength and bond-slip was understood to evaluate capacity deterioration of reinforced concrete, and experiments were carried out by compressive strength and embedded rebar condition in the rebar corrosion rate.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.4 s.70
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• pp.335-345
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• 2005

This paper concentrates on the nonlinear analysis of prestressed concrete (PSC) containment structures. Unlike a commercialized program which adopts the perfect bond assumption between concrete and tendon in the analysis of PSC structures, a numerical algorithm to consider the slip effect, simultaneously with the use of commercialized programs such as DIANA and ABAQUS, is introduced in this paper For bonded tendons, the apparent yield stress of an embedded tendon is determined from the bond slip relationship. And for unbonded tendons, Correction for the strength and stiffness of unbonded internal tendons is achieved on the basis of an iteration scheme derived from the slip behavior of tendon along the entire length. Finally, the developed algorithm is applied to two PSC containment structures of PWR and CANDU to verify its efficiency and applicability in simulating the structural behavior of large complex structures, and the obtained result shows that both containment structures represent the ultimate pressure capacity larger than about 3 times of the design pressure.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.636-639
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• 2004

Reinforced concrete structures have been used for a long time. However, corrosion problem in reinforcing steel is inevitable, which results in the degradation of performance and the shortening of the life of structures. To overcome such problems, FRP(Fiber Reinforced Polymer) rebars have been developed. Due to their corrosion resistance and their superior mechanical properties, FRP rebars are increasingly applied to concrete structures in other countries. To obtain the composite action between FRP rebars and concrete, sufficient bond between two materials must be secured. But, the behavior of FRP rebars is different from that of steel rebars. Therefore, it is necessary to understand and develop the proper bond mechanism of FRP rebars to use them in concrete structures. This paper presents analytical results to investigate the bond-slip relationship between FRP rebars and concrete based on pull out tests.

• Magazine of the Korea Concrete Institute
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• v.3 no.2
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• pp.115-121
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• 1991

Slippage of beam longitudinal reinforcement at beam-column connections is an important cause of damage to reinforced concrete frames under static and dynamic loads, This paper summarizes the results of an experimen¬tal study on the effects of confinements and compressive strength of concrete on the local bond stress-slip cha¬racteristics of deformed bars. I t is concluded from experimental results that, as far as the bond splittmg cracks are restrained by the vertical column reinforcement, confinement of concrete by transverse reinforcement has insignigicant direct effect on the local bond behavior. The ultimate bond strength, however, Increases pro¬portionally with the square root of concrete compressive strength. An empirical model was developed for local bond st ressslip relationslip of deformed bars in confined concrete of different compressive strengths.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.49-50
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• 2010

This study focuses on the bond performance of ribbed type of GFRP rebar to concrete at high temperature and discusses the results of pullout test. Pullout tests of ribbed type of GFRP rebars embedded in concrete were conducted to obtain an accurate bond stress-slip curves and also to closely observe the state of the surface of pulled-out rebars at failure. The effect of temperature on the bond strength is mainly discussed in this paper. Relatively high bond strength was seen in the control specimen which is exposed to room temperature. But, as the internal temperature increases, the bond strength decreases.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.1
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• pp.39-47
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• 2023

The demand for lightweight and high-strength materials is increasing. However, studies on the bond of concrete and reinforcing bars for high-strength lightweight concrete with a compressive strength of 120 MPa and a unit weight of 20 kN/m³ to structural members are lacking. Therefore, in this paper, 108 specimens of high-strength lightweight concrete with a compressive strength of 120 MPa and a unit weight of about 20 kN/m³ were fabricated, a direct pull-out test was performed, and the bond characteristics were evaluated by comparing the test results with design code. Compared to the decrease in unit weight, the solid bubble shows relatively little reduction in compressive strength and modulus of elasticity. It was f ound to have larger slip and parameter values than concrete with low compressive strength and unit weight.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.3
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• pp.100-107
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• 2010

This study evaluates the bond behavior of reinforced concrete (RC) beams using recycled coarse aggregates. A total of four specimens were cast and tested. The test parameter was the type of coarse aggregates, that is, natural and recycled coarse aggregates, and the absorption ratio of recycled coarse aggregate. The recycled coarse aggregates with absorption ratios of 3% and 6% were used in this test. The specimens were simply supported and were subjected to a concentrated load. A test method proposed by Ichinose was adopted to estimate effectively the bond properties of specimens. From the experimental results, it was found that there was no difference of bond characteristics according to the absorption ratio of recycled coarse aggregates.

• Computers and Concrete
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• v.13 no.3
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• pp.411-421
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• 2014

A central pullout test was conducted to investigate the bonding properties between high strength rebar and reactive powder concrete (RPC), which covered ultimate pullout load, ultimate bonding stress, free end initial slip, free end slip at peak load, and load-slip curve characteristics. The effects of varying rebar buried length, thickness of protective layer and diameter of rebars on the bonding properties were studied, and how to determine the minimum thickness of protective layer and critical anchorage length was suggested according the test results. The results prove that: 1) Ultimate pull out load and free end initial slip load increases with increase in buried length, while ultimate bonding stress and slip corresponding to the peak load reduces. When buried length is increased from 3d to 4d(d is the diameter of rebar), after peak load, the load-slip curve descending segment declines faster, but later the load rises again exceeding the first peak load. When buried length reaches 5d, rebar pull fracture occurs. 2) As thickness of protective layer increases, the ultimate pull out load, ultimate bond stress, free end initial slip load and the slip corresponding to the peak load increase, and the descending section of the curve becomes gentle. The recommended minimum thickness of protective layer for plate type members should be the greater value between d and 10 mm, and for beams or columns the greater value between d and 15 mm. 3) Increasing the diameter of HRB500 rebars leads to a gentle slope in the descending segment of the pullout curve. 4) The bonding properties between high strength steel HRB500 and RPC is very good. The suggested buried length for test determining bonding strength between high strength rebars and RPC is 4d and a formula to calculate the critical anchorage length is established. The relationships between ultimate bonding stress and thickness of protective layer or the buried length was obtained.