• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.4A
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• pp.307-313
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• 2009

In this study, in order to research the repair-strengthening methods, when fatigue crack occurs in the coped stringers of a steel railway bridge, we manufacture the full size of crossbeam-stringer and floor system model. Also the experimental test is performed on the coped stringers applying the repair-strengthening methods using the stop hole, combination plate, connection plate, bracket, and so on. The results indicate that, the most effective method is to set up connection plate and bracket in the top flange and bottom flange of the stringers, while we can consider the method of punching stop holes in the end of the crack as a subsidiary method. It is necessary to set up the combination plate when the length of crack is quite long.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.545-548
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• 1999

The purpose of this study is application of strengthening technique of R/C concrete bridge by standardization of repair and rehabilitation. For that, experiment to bridge is necessary, and through the experiment, this study can identify the efficiency o applied method and analysis of design parameters with can't get in the laboratory experiment. This study will prove the structural behavior of R/C type girder bridge which is deteriorated but repaired and rehabilitation from standardized strengthening method with fiber plastic.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.503-508
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• 2001

With difference to strengthening which could be evaluated structural efficiency, it is hard to do quantitative repair efficiency evaluation achieved compressive strength test or appearance investigation. In this paper, chloride ion penetration test is exacted to core specimens picked from repaired structure for quantitative repair evaluation. The result of experimentation shows repair efficiency quantitatively by means of difference between penetration amount of chloride ion for repaired and unrepaired core specimens.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.553-558
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• 2000

In this study, a numerical simulation that can effectively predict the interfacial fracture behavior in repaired structures is developed using the axial deformation link elements. In repaired structures, concrete and interface are considered as quais-brittle materials, and steel plate as a repair material and reinforcement are modeled as elasto-plastic materials. The behavior of repaired reinforced concrete structures under flexural loading conditions is numerically simulated, and compaired with experimental results. The strengthening effect according to the length and thickness of the repair material is studied and rip-off, debonding and rupture failure mechanism of interface between substrate and repair materials are detected. It is shown that the interface properties affect on the mechanical behavior of repaired structures. Therefore, the developed numerical method using axial deformation link elements can be used for determining the strengthening effects and failure mechanism of repaired structures.

• Journal of the Society of Disaster Information
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• v.12 no.1
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• pp.54-61
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• 2016

The use of advanced composite materials in strengthening and repair of existing structures is increasing rapidly. This paper describes an effectiveness of a bonding of carbon fiber reinforced sheets to corroded steel members for the repair. Three types of surface treatment, what we call cleaning, of corroded plate are chosen as parameters. They are "without cleaning","removal of painting by brushing" and "complete removal of painting". From the experimental study, the following findings are obtained. 1) When the steel plate is subjected to tensile force, carbon fiber sheets adhered to the painted steel gives a higher strength against peeling compared to that of the plate without painting, 2) The grade of surface treatment, or cleaning of the corroded steel plate affects the strengthening effect.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.781-786
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• 2000

This paper presents the behavior and strenghening effect of reinforced concrete rectangular beams strengthened sing CFRP sheets with different strengthening level. In general, normally strengthened beams are failed by interfacial shear failure (delamination) within concrete, instead of by tensile failure of the CFRP sheets. The delamination occurred suddenly and the concrete cover cracked vertically by flexure was spalled off due to the release energy. The ultimate load considerably increased with an increase of strengthening level, while the ultimate deflection significantly decreased. The tensile force of CFRP sheets and average shear stress of concrete at delamination failure were curvilinearly proportional to the strengthening level. Therefore, the increment of ultimate load obtained by strengthening was curvilinearly proportional to th strengthening level.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.703-708
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• 1999

The concrete structure under fatigue load depresses in mechanical capability or breaks down finally because of the fatigue. So recently the study on strengthening methods using bonded steel plate is widely attended. Which could be constructed under use and without damaging the structure. The intention of this method is to increase the useability of the structure and to recover the strength. So application on fields are sharply increasing. In this study it is tried to develop strengthening methods using notches and anchor bolts which could supply the defect on falling off of the steel plate at the end.

• Magazine of the Korea Concrete Institute
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• v.7 no.6
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• pp.38-49
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• 1995

• Journal of the Korea Construction Safety Engineering Association
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• s.31
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• pp.60-72
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• 2005

• Journal of the Korea Concrete Institute
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• v.12 no.1
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• pp.69-77
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• 2000

Recently, many strengthening methods are developed to repair damaged structures, when the original structure is under loading, which causes the difference of initial stresses between original member and bonded material. However, current design method or theory, which mostly depends on ultimately strength design, cannot account the difference of initial stresses between members, and it disregards the reduction of nominal strength. In this study, a new strengthening design theory and the amount of strengthening which can account the difference of initial stresses are developed, and applied to the case when a structure in service is repaired. The results show that the amount of strengthening material depends on the status of damages of structure, and the nominal strength is reduced depending on the degree of damages.