• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.2
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• pp.143-151
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• 2021

Flexural test of reinforced concrete beam with corroded reinforcement were performed to measure the deflection, curvature and cracking moment for various bar diameter and amounts of corrosion. The amounts of corrosion are varied from 0% to 10% by weight and the bar diameters are chosen as 10mm, 13mm, and 19mm. The changes in reinforcement diameter do not affect the flexural behaviors significantly according to this experiment. If the amounts of corrosion is greater than 2%, the deflection and curvature of the beam increased and the cracking moment decreased. It means that the lower amounts of corrosion does not result structural damage in flexural member significantly as in direct tensile test. A modification factor considering an effect of amounts of corrosion is proposed based on the experiment, which can be used to determine the deflection of reinforced concrete beam with corroded reinforcement.

• International Journal of Highway Engineering
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• v.8 no.1 s.27
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• pp.119-130
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• 2006

The behavior of continuously reinforced concrete pavement (CRCP) and the effect of the steel ratio on the behavior under moving wheel loads were investigated in this study. The CRCP sections having different steel ratios of 0.6, 0.7, and 0.8% were considered to evaluate the load transfer efficiency (LTE) at transverse cracks and to investigate the strains in CRCP when the system is subjected to moving vehicle loads. The LTEs were obtained by conducting the falling weight deflectometer (FWD) tests and the tests were performed at three different times of a day to find the curling effect due to the daily temperature changes in CRCP. The strains in the concrete slab and the bond braker layer of the CRCP system under moving vehicle loads were obtained using the embedded strain gages. The results of this study show that the LTEs at transverse cracks are very high and not affected by the time of testing and the steel ratio. The strains in CRCP under vehicle loads become smaller as the vehicle speed increases or as the wandering distance increases; however, the strains are not clearly affected by the steel ratio.

• Journal of the Korea Concrete Institute
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• v.19 no.6
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• pp.685-692
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• 2007

When the shear force governs the response of an RC element, as in the case of a low-rise shear wall, the effect of shear on the element's response is thought to be responsible for the 'pinching effect' in the hysteretic loops. However, it was recently shown that this undesirable pinching effect can be eliminated in the hysteretic load-deformation curves of a shear-dominant element if the steel grid orientation is properly aligned in the direction of the applied principal stresses. In this paper, the presence and absence of the pinching mechanism in the hysteretic loops of the shear stress-strain curves of RC elements was explained rationally using a compatibility aided truss model. The analytical results indicate that the pinching effect of the RC elements is strongly related to the direction of the steel arrangement. The area of the energy dissertation does not increase proportionally to the difference between the direction of the principal compressive stress and the direction of the steel arrangement.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.87-88
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• 2010

The strength and ductile capacity of reinforced concrete column can be improved by confinement using transverse reinforcement. Variety stress-strain models about the reinforced concrete confined by transverse reinforcement has been proposed. In this paper, parameters which effect to the ultimate confinement stress of circular cylinder confined by high strength transverse steel is examined. And the possion's ratio equation is proposed by analysis of strain between concrete and transverse reinforcement.

• Journal of the Korea Concrete Institute
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• v.26 no.3
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• pp.299-306
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• 2014

Coating is one of the methods used to solve the problem of corrosion of reinforcement in concrete structures. There are few research reported in the literature regarding the effect of zinc-coating on flexural behavior compared to epoxy coating. The objective of this study was to determine whether zinc-coated rebar adversely affects flexural behavior. Concrete beams reinforced with black or zinc-coated steel were tested in flexure. The test variables included the presence of rebar surface coating with zinc, steel ratio used and cover depth. The study concentrated on comparing crack pattern, crack width, deflection and strain. The ultimate flexural capacity of beams reinforced with zinc-coated bars was not different from that of black steel reinforced beams. The results from deflection and crack width measurements were indicative of no significant variation for the different rebar surface conditions. In addition, it was found that load-strain curve of beam reinforced with zinc-coated steel was similar to that of beam reinforced with zinc-coated steel. Therefore, the test results indicated that the use of zinc-coated rebar had no adverse effect on flexural behavior compared to the use of black rebar.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.3
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• pp.47-57
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• 2023

In this study, pull-out tests were performed to investigate the effects of stirrup spacing, rebar diameter, and corrosion rate on bond strength of deformed bars in reinforced concrete. Twelve pull-out specimens with different stirrup spacing, rebar diameter, and corrosion rate were prepared following the RILEM RC6 guidelines. The test results showed that the bond strength of specimens with stirrups increased when the corrosion rate was less than 3%, whereas it decreased when the corrosion rate was more than 3%. On the other hand, the bond strength of specimens without stirrups decreased as the corrosion rate increased. The effect of rebar diameter was less significant compared to those of stirrup spacing and corrosion rate. A bond strength model for pull-out specimens was proposed considering stirrup ratio and corrosion rate, and the model showed the lowest error among the previous models.

• Journal of the Korea Concrete Institute
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• v.22 no.6
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• pp.825-832
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• 2010

Although a critical section reaches its flexural strength in reinforced concrete structures, the structure does not always fail because moment redistribution occurs during the formation of plastic hinges. Inelastic deformation in a plastic hinge region results in plastic rotation. A plastic hinge mainly depends on material characteristics. In this study, a plastic hinge length and plastic rotation are evaluated using the flexural curvature distribution which is derived from the material models given in Eurocode 2. The influence on plastic capacity the limit values of the material model used, that is, ultimate strain of concrete and steel and hardening ratio of steel(k), are investigated. As results, it is appeared that a large ultimate strain of concrete and steel is resulting in large plastic capactiy and also as a hardening ratio of steel increases, the plastic rotation increases significantly. Therefore, a careful attention would be paid to determine the limit values of material characteristics in the RC structures.

• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.2
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• pp.142-147
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• 2007

In order to measure corrosion level of steel reinforcement rebar which is inside reinforced concrete structure, infrared thermographic technique was employed. Experimental test parameters were four different ambient temperatures and various levels of corrosion states (0, 1, 3, 5, 7 and 10% of weight loss). After analysis of temperature distributions of concrete surface, the amount of heat flux from the concrete surface is directly proportional to the corrosion level which is inside of concrete.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.1
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• pp.24-31
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• 2011

In order to measure corrosion level of reinforcement rebar in RC structures, non-destructive test methods which are concrete surface current density method and infrared thermographic technique were employed to measure corrosion levels. Experimental test parameters were various levels of corrosion states(0, 1, 3, 5, 7% of weight loss) and concrete cover depth(30 mm, 40 mm) and two different reinforcing rebar arrangements. The larger amount of concrete surface current density, the higher corrosion level in reinforcement rebar. The laboratory conditions which are ambient temperature and humidity have negligible effect on the infrared thermographical data. After analysis of current density and temperature distribution from concrete surface, corrosion level of reinforcement rebar embedded in concrete can be measured qualitatively based on the amount of electric current and heat flux.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.6551-6557
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• 2015

This paper discusses the surface roughness of corroded reinforcement rebar-in-coil focusing on the quantitative measurement technique using 3D scanner. Reinforcement rebar-in-coil was stacked in site for 0 day, 3 days, 7 days, 14 days and 21 days. And rebar-in-coil was corroded 0.04%, 0.3367%, 0.6157%, 0.7898%, and 1.1965% respectively. Using 3-dimensional scanner, each surface profile of reinforcement rebar-in-coil was established, and surface roughness was measured. Through the tests and analyses of corroded rebar-in-coil, the increase of fractal dimension for each rebar-in-coil was measured as 0.0216, 0.0235, 0.028, 0.0319, and 0.0455 for different stacked periods. Therefore, surface assessment technique using fractal dimension showed similar results with the actual corrosion rate.