• Structural Engineering and Mechanics
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• v.46 no.5
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• pp.615-627
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• 2013

One of the most common defects in reinforced concrete bridge decks is corrosion of steel reinforcing bars. This invisible defect reduces the deck stiffness and affects the bridge's serviceability. Regular monitoring of the bridge is required to detect and control this type of damage and in turn, minimize repair costs. Because the corrosion is hidden within the deck, this type of damage cannot be easily detected by visual inspection and therefore, an alternative damage detection technique is required. This research develops a non-destructive method for detecting reinforcing bar corrosion. Experimental modal analysis, as a non-destructive testing technique, and finite element (FE) model updating are used in this method. The location and size of corrosion in the reinforcing bars is predicted by creating a finite element model of bridge deck and updating the model characteristics to match the experimental results. The practicality and applicability of the proposed method were evaluated by applying the new technique to a two spans bridge for monitoring steel bar corrosion. It was shown that the proposed method can predict the location and size of reinforcing bars corrosion with reasonable accuracy.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.503-507
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• 2000

The corrosion protection methods of reinforcing steel in concrete are the various methods such as increasing thickness of cover concrete, using of reinforcing bars coated with epoxy, dosage of corrosion inhibitor as concrete admixture, cathodic protection method and etc. In this study, the performance of corrosion protection was investigated for the test specimens using corrosion inhibitors and cathodic protection, respectively. For this purpose, the accelerated corrosion tests for reinforcing steel were conducted according to the periodic cycles(140 days) of wetting($65^{\circ}C$, 90% R.H) and drying period($15^{\circ}C$, 65% R.H) for the test specimens. As a result, it can be concluded from the test that the effect of corrosion inhibitor was found to be variable with products, the cathodic protection method was found to be independent of salt concentration in concrete.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.04a
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• pp.141-148
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• 1998

The chloride attack of the top mat of reinforcing bars is a major cause of deterioration of comcrete deck of plate girder bridges. This is caused by a current design method which requires a top mat of reinforcing bars to resist a negative bending moment in bridge decks. In recently, empirical evidence has indicated that the top transverse reinforcing bars can patially or fully be eliminated without jeopardizing the structural integrity of a deck. So, one of the most efficient way to increase durability of concrete deck of bridges is the development of new design method that reduce or eliminate the top mat reinforcing bars, mad it is possible by the exact analysis that considering the negative bending moment reducing effect which introduced by relative deflection of plate girders. In this study, we develop the new bridge deck analysis method that considered the effect of relative girder deflection by applying the principles of slope deflection method of frames, and that is fine tuned with results of finite element analysis. This new approach evaluate a bending moment in a deck based on the effect of relative girder deflection as well as the magnitude of wheel loads, the girder spacing and stiffness, deck stiffness and the span length

• Journal of the Korea Institute of Building Construction
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• v.21 no.6
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• pp.617-627
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• 2021

In this study, a numerical analysis using a three-dimensional numerical simulation was performed to assess the applicability of foundation reinforcing method using load transfer apparatus which can be used in the remodeling of deteriorated structures. The numerical model was validated through comparison with the real scale experimental results, and then a parametric study was performed to investigate the effect of friction coefficient of load transfer apparatus and axial stiffness of pile on the performance of foundation reinforcing method. It was confirmed that the foundation reinforcing method considered in this study can efficiently control the load applied to an existing foundation.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.201-204
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• 2006

The shear resistance of RC beams is subject to the amount of shear-reinforcing bars ($p_w$) and yield strength ($f_{wy}$) as well as their interactive influence ($p_wf_{wy}$). Thus, it is reasonably expected that high-strength steel bars can greatly reduce the necessary amount of shear-reinforcing bars. On the other hand, although the bond strength is influenced by the amount of shear reinforcing bars, it is not affected by the yield strength. Thus, there is often an issue that bond failure occurs before shear failure depending on the arrangement of shear reinforcing bars. It is a common practice to set sub-ties for the transverse confinement of the main re-bars as a method to prevent the bond failure. However, it can also become a factor in decreased work efficiency due to the complexity of the construction. This study experimented with simultaneous use of high-strength transverse reinforcing bars ($f_{wy}=800MPa$) and U-shaped transverse reinforcing bars of regular strength ($f_{wy}=300MPa$) in an attempt to decrease the necessary quantity of shear reinforcing bars. The effect of this attempt was investigated through fundamental experimental research in terms of the improvement in shear resistance and bond strength as well as the ease of construction.

• Journal of the Korean GEO-environmental Society
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• v.9 no.6
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• pp.5-12
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• 2008

In this research, the plate load tests on sand which is reinforced by Tirecell mat were simulated by finite element method (FEM). Tirecell mat made by waste tires has the same function and similar shape to Geocell for soil reinforcement and it can also be used for civil engineering structure. The results were compared with those of field plate load tests for evaluation of suitability of modeling method. From the comparison of both results, it can be seen that the settlements by FEM were very similar to test results with small margin under the ultimate bearing capacity. For the ultimate bearing capacities of two results, difference was very small. After the confirmation of the modelling, reinforcing effects with variation of cover depth and number of reinforcement layers by Tirecell were analyzed additionally. Reinforcing effect decreases with increasing soil cover depth, and this is similar to previous test results by soil cover depth. As the number of reinforcing layers increased, reinforcing effect increased. However at more than 2 reinforcing layers, reinforcing effect was negligible. In conclusion, the modeling method in this research might be used for analysis of reinforced structures using Tirecell mat.

• Journal of the Korean Geotechnical Society
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• v.26 no.10
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• pp.5-14
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• 2010

The slope stability method using the soil stabilizer is a way to ensure that the slope stability from reinforcing method is environmentally friendly. However, the reinforcing method does not ensure slope stability for lack of research on the reinforcement effect of the mixture with soil. So the application of this method implies difficult technical issues. In this research, reinforcement effect is investigated according to the different ratio of mixture. And the optimum reinforcement depth is proposed according to the height of slope from numerical analysis. The results show that approximately the soil strength increases from two to three times. From numerical analysis, it is possible to estimate the optimum height according to the height of slope. It is anticipated that the use of soil stabilizer will increase the slope stability.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.807-812
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• 1999

Locating of reinforcing bars, in particular to know their accurate depths, is very important thing in radar inspection of concrete structures. By the way, a depth estimation of reinforcing bars in concrete structures by the radar is not easy because micorwave propagation velocity in test area is generally unknown. This problem can be solved by Generalized Hough transformation technique. Using this technique, the micorwave propagation velocity in test area can be detected from the radar image, which appear as hyperbolas conveying the velocity information in their shape. A developed speed-up technique for the computation of the Generalized Hough transformation is also investigated in this study. As a result, although it becomes difficult to locate reinforcing bars when multiple parallel bars lying too close together, there is a possibility of detecting accurate depths of reinforcing bars in test area by the proposed method.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.04a
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• pp.471-476
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• 2003

The presence of voids under pavements or behind tunnel linings results in their deterioration. To detect these voids effectively by non-destructive tests, a method using radar was proposed. In this research, not only the detection of shape of voids, but also the location of reinforcing bars by radar image analysis is investigated. The experiments and image processing were conducted to detect voids and to locate reinforcing bars in or under concrete pavements (or tunnel linings) with reinforcing bars. From the results, the fundamental algorithm for tracing the reinforcing bars and voids, improving the horizontal resolution of the object image and detecting shape of objects, was verified.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.579-584
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• 1997

This experimentation is to apperciation an efficiency of repair for processing crack by corrosion of steel reinforcing, Crack on concrete by corrosion of steel reinforcing is the fact that the first crack appear on the surface of water because of supplying is of oxygen and water. The crack processing is on surface to be contacted by air and to bottom as mainly the vertical direction from a surface of water. The experimentation gives rise to crack in model by electricity. Crack by corrosion of steel reinforcing is more internal crack than external crack. since it is so. crack by corrosion of steel reinforcing have to attention to repair or intermal crack.