• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.255-258
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• 2009

본 논문에서는 최근 건축구조물의 보수보강에 사용되고 있는 복합재료보의 정확한 보강성능을 규명하기 위하여 다양한 실물 실험을 수행하였으며 실험 결과를 검토하여 실제 보강효과를 검증하였다. 콘크리트의 재료비선형을 고려할 수 있는 수치해석 기법으로 실험결과를 재현하여 보강효과를 수치해석적으로 검증하였으며 복합재료보를 이용하였을 경우 확보할 수 있는 보강효과에 대하여 연구하였다. 일반적인 철근콘크리트 구조물에 복합재료보를 이용하여 보강하였을 경우, 약 80% 내외의 하중 증가효과를 확보할 수 있었다. 또한 수치해석을 통하여 보강효과를 검토한 결과, 실물실험과 유사한 결과를 얻을 수 있었으며 복합재료보의 시공시 사용되는 전단연결재의 효과를 고려한다면 거의 동일한 결과를 얻을 수 있을 것으로 판단된다. 현재까지의 연구결과, 복합재료보를 이용하여 구조물을 보강한 경우, 취성이 증가하는 것으로 알려져있으나 추가적인 연구를 통하여 연성을 확보할 수 있는 복합재료보의 연구개발이 가능할 것으로 예상된다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.4
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• pp.100-107
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• 2018

The objective of this study is to assess the strengthening effects of fiber reinforced polymer(FRP) sheets such as Carbon fiber, Glass fiber, and PET(polyethylene terephthalate) on reinforced concrete flexural members. Variables of theoretical analysis are types of strengthening materials, material properties and amount of strengthening materials. A virtual flexural member without FRP sheets was created as a control specimen to understand the structural behavior of the non-strengthened specimen in terms of elastic and ultimate cross section. In total, 11 specimens including one non-strengthened and ten strengthened specimens were investigated. Various variables such as types of strengthening, strengthening properties, and amount of strengthening were studied to compare the behavior of the control specimen with those of strengthened specimens with regard to moment-curvature relationship. Results of theoretical analysis showed that the moment capacity of strengthened specimens was superior to that of the control specimen. However, the control specimen indicated the best ductility among all the specimens. As the amount of strengthening increased, flexural performance was improved. Furthermore, the results indicated that the ductile effect of members was affected by the ultimate strain of FRP sheets. The strengthening effect on the damaged member was similar to that on the non-damaged one since there was less than 10% difference in terms of flexural strength and ductility. Therefore, even if a damaged member is treated as non-damaged for analysis there is probably no noticeable difference.

• Journal of Korean Association for Spatial Structures
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• v.5 no.2 s.16
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• pp.65-71
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• 2005

The reinforced concrete becomes deteriorated. In strengthening of reinforced concrete structure, it is recently useing FRP. In research, flexural strengthening of reinforced concrete beam can be Efficient design. But shear srengthening og reinforced concrte beam can't be Efficient design by variable cause. The purpose of this study is to investigate the shear resisting effect of filling-up CFRP in reinforced concrete beams with web reinforced. Ten specimens were manufactured and tested. In the test result, it was analysis. The main variables in the test were a space of web reinforcement and a direction of CFRP.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1997.11a
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• pp.171-176
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• 1997

본 연구에서는 노후화 된 구조물을 효과적으로 보강할 수 있는 방법에 대해 휨 거동을 중심으로 그 성능을 규명하고자 하였다. 연구에 채택된 보강재료로는 현재 시공의 간편성과 보강된 부재 단면의 최소화로 최근에 각광을 받고 있는 섬유접착 보강재료 중에서 탄소섬유쉬트(CFS)와 아라미드섬유쉬트(AFS) 접착공법을 선택하였으며, 현재 상용중인 보강단면을 채택하여 보수ㆍ보강을 실시하였다. 그리고, 보강효과를 실험을 통하여 비교ㆍ분석함으로써 합리적인 보수ㆍ보강공법을 위한 선택의 폭을 넓히고, 현재 활발히 진행중인 국내 보수ㆍ보강의 체계화를 위한 기초적인 자료를 얻고자 한다. (중략)

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.6
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• pp.183-190
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• 2006

From the result of this research above, it may be summed up as follows. As a summary of results from each experiment, as the test body reinforced with the carbon rods was embedded inside the concrete section and made it possible uniform movement, this study has shown that it had excellent characteristics in improving the flexural strength and ductility. Also, it was considered as the carbon-steel sheet composite plate was to exert the strength more if it would complement the adherence with the concrete.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.1
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• pp.171-178
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• 2019

Fiber-reinforced polymer (FRP) composites have proved to be reliable as strengthening materials. Most of existing studies used single types of FRP composites. Therefore, in this experimental study, carbon FRP sheet, aramid FRP sheet, and hybrid FRP plate including glass fibers were fabricated, and the effect of pre-stressed FRP composites on flexural strengthening of reinforced concrete (RC) beams was investigated. In total, eight RC beam specimens were fabricated, including one control beam (specimen N) without FRP composites and seven FRP-strengthened beams. The main parameters were type of FRP composite, the number of anchors used for pre-stressing, and thickness of FRP plates. As a result, the beam strengthened with pre-stressed FRP plate showed superior performance to the non-strengthened one in terms of initial strength, strength and stiffness at yielding, and ultimate strength. As the number of anchors and thickness of FRP plate (i.e., amount of FRP plates) increased, the strengthening effect increased as well. When hybrid FRP plates were pre-stressed, the strengthening effect was higher in comparison with pre-stressed single type FRP plate.

• Journal of Korean Society of Steel Construction
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• v.21 no.4
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• pp.385-392
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• 2009

In this study, the confining effect of the proposed steel jackets and GFRP tubes for concrete was investigated. The new steel jacket differs from the existing steel jacket in terms of installation technique and behavior. Thus, it is necessary to assess its confining effect on concrete. Moreover, the method was compared to GFRP tubes to investigate its strong and weak points. The confining effect of the proposed steel jacket was shown to correspond with that presented in the previous researches. The GFRP jacketing method, however, does not show any confining effect in some cases, according to the tube thickness and concrete peak strength as such, the previous assessment equation cannot be used in such cases. Thus, in this study, a new method of assessing the peak strength of confined concrete was suggested, and the minimum thickness was determined to show the confining effect. Lastly, the ultimate strains of concrete that had been confined through the two methods were compared to assess their ductile behavior.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.3
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• pp.178-186
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• 2005

In this study, the PSC girder bridge retrofitted with external tendons is tested to verify the strengthening effects. We measure the variations of the displacement and strain at mid-span of each beam as external tendons are removed in sequence. The structural behavior of the bridge are examined using controlled truck load tests for the systems before and after all external tendons were removed. From the test results, the characteristics of structural behavior of the bridge do not change significantly, but the natural frequency is decreased after the external tendons are removed. The strengthening effects of bridges can be exactly estimated by analytical methods some extent. As a result of this study, when a PSC girder bridge is deteriorated, the bridge can be retrofitted effectively by External Prestressing Strengthening Method, and the strengthening effects can be predicted through accurate structural analysis.

• Journal of Korean Association for Spatial Structures
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• v.5 no.2 s.16
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• pp.57-63
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• 2005

The reinforced concrete becomes deteriorated. In strengthening of reinforced concrete structure, it is recently useing FRP. The purpose of this study is to investigate the shear resisting effort of filling-up CFRP in reinforced concrete beams without web reinforced. Six specimens were manufactured and tested. In the test result, it was analysis. The main variables in the test were a space and volume of CFRP.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.10b
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• pp.44-58
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• 2001

FRP(Fiberglass Reinforced Plastic)관을 이용한 사면보강은 천공 후 그라우트재에 압력을 가하여 그라우트재의 천공홀 충전뿐만 아니라 지반으로의 침투주입 효과를 일으켜, 전체적인 보강력 증대를 기대하는 공법이다. 이런 특성을 설계에 반영하기 위해서는 구조재료인 FRP관 자체에 의한 지반보강효과 뿐만 아니라 그라우팅에 따른 지반강도의 증진효과를 정량적으로 평가하는 것이 선행되어야 하나 아직까지는 이에 대한 연구가 부족한 실정이다. 따라서 대상지반을 토사와 암반사면으로 구분하여 각각의 보강효과를 확인하고자 현장시험 및 수치해석을 실시하였으며, 이로부터 지반종류에 따른 보강특성과 합리적인 설계를 위한 설계인자를 추출하고자 하였다.