• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.835-840
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• 2002

Chloride ions have a tendency to penetrate into concrete and proceed the corrosion by depassivating rebar surface. Thus tire deteriorated concrete is subject to experience severe degrading of durability under marine environment. In this study, concrete structures exposed to reclaimed marine land wet-e investigate to find out the salt attack along with analysis and review of it's cause. Under the reclaimed marine land, the main causes of deterioration of concrete structures is the steel corrosion due to the Penetration of chlorides and the deterioration of outer concrete itself by chemical attack.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1995.04a
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• pp.136-143
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• 1995

The problem of the structural identification becomes important, particularly with relation to the rapid increase of the number of the damaged or deteriorated structures, such as highway bridges, buildings, and industrial facilities. This paper summarizes the recent studies related to those problems by the present authors. The system identfication methods are generally classified as the time domain and the frequency domain methods. As time doamin methods, the sequential algorithms such as the extended Kalman filter and the sequential prediction error method are studied. Several techniques for improving the convergences are incorporated. As frequency domain methods, a new frequency response function estimator is introduced. For damage estimation of existing structures, the modal perturbation and the sensitivity matrix methods are studied. From the example analysis, it has been found that the combined utilization of the measurement data for the static response and the dynamic (modal) properties are very effictive for the damage estimation.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04b
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• pp.633-636
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• 1998

This study is performed for the purpose of obtaining the fundamental datum to analyse the cause of steel corrosion in concrete and establish the repair strategies of deteriorated reinforced concrete structures due to steel corrosion. To investigate the degree of concrete deterioration, soluble chloride content in harden concrete, the depth of carbonation, cover depth and compressive strength are measured. The progress of corrosion of concrete bridge is electrochemically evaluated. The result shows that in approximately 43% of the structures below -350mV(vs. CSE), the exessive chloride contents is a direct cause of steel corrosion in reinforced concrete structures.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.05a
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• pp.203-206
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• 2005

The purpose of this study is to develop the evaluation method of repair performance for the repair method of reinforced concrete structures deteriorated due to combined deterioration, its results are summarized as the follows. After investigating and analyzing the experimental data of this study and existing research, it is proposed the evaluation method on the repair performance for the repair method of reinforced concrete structures using evaluation method of reinforcing corrosion by combined deterioration accelerated test.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.653-658
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• 1997

Recently, carbon Fiber sheet (CFS) is frequently used for strengthening deteriorated concrete structures. To strengthening damaged structures, the property and characteristic of the bond between CFS and the concrete surface must be understood. The tensile test of single lap shear specimen was performed to study bond strength, bond stress distribution and stress transfer between CFS and concrete surface according to the bond length. Based on the test results, there were ultimate influence length (UIL) in which bond stress was distributed, and ultimate strain reduction ratio (USRR) by which strain was reduced linearly. Bond resisting force (BRF) was estimated by UIL and USRR, and which was compared with ultimate loads. According to the results of comparison, it was shown that ultimate bond strength could be estimated reasonablely by BRF.

• Proceedings of the Korea Concrete Institute Conference
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• 1991.10a
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• pp.158-161
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• 1991

By applying the newly developed techniques of polymer impregnated concrete (PIC) severely deteriorated and low quality concrete can be restored to an adequate structural material. Early deterioration of concrete causes severe problems for bridge deck concrete, pavement concrete for highways and airports, hydraulic structures and buiilding structures. Deterioration has its orgin in cracks on concrete surface, scaling of spalling due to freezing and thawing, neutralization of concrete, penetrations of water, salt, and calcium chloride. The objective of this study is to develope the new surface impregnants and strengthening techniques for them. It is found that the new impregnants and strengthening techniques developed in this study can retian the charecteristics of the existing concrete and decrease deterioration, and also increase durability, chemical resistance, strength, stiffness and ductility of the existing concrete.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.05a
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• pp.29-30
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• 2013

Steel corrosion is the most serious problem in RC structures. Even though patch repair method is normally applied in repair system, the effectiveness is not enough. Cathodic protection in active repair method to deteriorated RC structures. FEM model was developed to simulate the optimized cathodic protection condition. Iro oxidation, hydrogen evolution and oxygen reduction were considered to expect current distribution. Moisture content in concrete which can affect the electrolyte conductivity was used as initial condition.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.1
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• pp.223-230
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• 2006

In this paper the method for repair LCC evaluation of reinforced concrete structures deteriorated by chloride attack was constructed. Also, the FEM analysis for chloride ion penetration into concrete was conducted to evaluate the repair LCC which was decided by the number of repair times including early stages of construction and repair construction during the service life of structures. As a result, the number of repair times is obtained from the comparing the concentration of the chloride ion in a rebar position, and the critical chloride ion concentration of rebar corrosion through the FEM analysis considering the kind of repair materials and methods. Also, the repair LCC could be calculated by the number of repair times during the service life of structures.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.72-75
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• 2004

Carbon Fiber Reinforced Polymer(CFRP) composites are widely applied to strengthen deteriorated concrete structures. This paper presents the experimental results of the performance of reinforced concrete(RC) beams strengthened with externally prestressed CFRP plates. Simple beams with 3 m span length were tested to investigate the effect of prestressing force of CFRP plates on the flexural behavior of externally strengthened RC beams.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.165-168
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• 2005

Carbon Fiber Reinforced Polymer(CFRP) composites are widely applied to strengthen deteriorated concrete structures. This paper presents the experimental results of the performance of reinforced concrete(RC) decks strengthened with CFRP composites. Simple span decks with 2m span length were tested to investigate the effect of CFRP reinforcement types on the flexural behavior of strengthened RC beams. The test results were analyzed with the special emphasis on the failure mode and the maximum load.