• Title/Summary/Keyword: strengthening repair

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Structural behavior of R/C Slabs Strengthened with Steel Plate, Carbon fiber sheets, and Carbon Fiber Laminate. (강판, 탄소섬유쉬트, 탄소섬유판으로 휨보강된 철근콘크리트 슬래브의 구조적 거동)

  • Lee, Young-Jea;Moon, Heui-Jeung;Lee, Kyung-Un;Chung, Lan;Jung, Sang-Jin
    • Proceedings of the Korea Concrete Institute Conference
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    • 1998.04b
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    • pp.601-606
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    • 1998
  • In recent years, strengthening by steel plate, carbon fiber sheets, and carbon fiber laminate in spotlighted in order to repair and rehabilitation of R/C slabs. In this study, 3 method of rehabilitation are analyzed from the tests. Test parameters are the width of cracks, the method of repair and rehabilitation, the magnitude of pre-load. Deflection, failure load, strains of reinforcing bar, strains of sheet and plates are measured during tests. The failure mode and separption load analyzed from these measured data.

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Comparative Study on the Strengthening Effect of R/C Beams with Rebar, Steel Plate of CFRP (철근, 강판 및 CFRP를 적용한 R/C보의 보강효과 비교연구)

  • 심종성;황의승;최완철;배인환
    • Proceedings of the Korea Concrete Institute Conference
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    • 1996.04a
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    • pp.323-327
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    • 1996
  • Reinforced concrete(R/C) structures need repair and rehabilitation due to the deterioration such as a crack, spalling and disintergration. Numerous repair materials which are currently used in construction fields without any regulation are examined in terms of their serviceabilities and effectiveness. In this paper section of existing R/C beams are enlarged with repair materials, that is, epoxy, latex or premix. And then they are strengthened with rebar, steel poate of CFRP on the tension face. Structural behaviors of strengthened beams are investigated both statically and dynamically and they are compared with each. This paper summarizes the overall research plan.

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Fatigue Crack Growth Behavior of the Thin-to-Thick Type Stiffened Panels with Bonded Patch (접착 패칭된 박-후판 결합형 보강판의 피로균열성장 거동)

  • Rhee, Hwan-Woo;Kim, Seung-Hyun
    • Journal of Ocean Engineering and Technology
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    • v.22 no.3
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    • pp.89-95
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    • 2008
  • Fatigue cracked components often needs to be repaired during service. Standard repair schemes involve strengthening the component by connecting reinforcing members by means of rivets or welding by reducing the crack-tip stress intensity factors. Recent technological advances in fiber reinforced composite materials and adhesive bonding have led to the development of efficient repair schemes. In this study, the influence of various shape parameters on fatigue crack growth in the CCT type uniform thickness plates and the thin-ta-thick type stiffened panels repaired with woven fabric type Kevlar-Epoxy composite patch are studied experimentally.

An Evaluation on the Flexural Strength of Concrete Beams Repaired by Polymer Resin (폴리머계로 보수한 철근콘크리트 보의 휨성능 평가)

  • Kim, Byung-Guk;Shin, Young-Soo;Hong, Gi-Suop;Hong, Yung-Kyun;Choi, Oan-Chul
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.1 no.1
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    • pp.107-112
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    • 1997
  • A series of reinforced concrete beams was tested to evaluate the flexural performance of the repaired RC beams. The key parameters for this study were the size and location of the patch, and the repair materials, including polymer, polymer-cementitious and cementitious materials. The repaired specimens failed by a typical flexural mode with minor interfacial bond failure. Beams repaired with polymer, polymer-cementitious and cementitious materials recover 100%, 91%, and 97% of the flexural strength respectively, while beams with cement mortar lose approximately 30% of the strength. Compared with the pressure injection techniques the specimens repaired with patching techniques show low flexural strength, with significant interfacial bond failure. Location and size of the repaired part do not affect the recovering performance. Interfacial behavior between repair and strengthening materials is the major influencing factor for the composite structures.

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Effect of Evaluation before Site Application of Poly-acrylic Resin Leakage Repair Materials (폴리아크릴 레진 누수보수재의 선정평가 후 현장 적용에 따른 효과 분석)

  • Cho, Il-Kyu;An, Ki-Won;Song, Je-Young;Oh, Sang-Keun
    • Journal of the Regional Association of Architectural Institute of Korea
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    • v.20 no.6
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    • pp.55-61
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    • 2018
  • This study improved the water repair materials of the polyacrylic system applied to concrete structures by controlling expansion, strengthening water resistance, and improving cohesiveness. The improved polyacrylate repair materials were evaluated against the existing products to verify their performance and level of improvement, and applied on-site to the concrete structures that are leaking the improved water. The verification method measured the presence of water leaks and the moisture content of concrete inside. Moisture levels were measured for two months before and after material installation, and at least 0.8 - 1.7% of humidity was reduced after installing polyacrylic resin, and no leakage was found.

Performance of RC Beams Strengthened with FRP-Aluminum Composite Hollow Beam Under the Fire (RC보에 대한 FRP-Aluminum 유공복합보의 보강성능에 관한 연구)

  • Lee, Jae-Ik;Choi, Yeol
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.14 no.2
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    • pp.153-160
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    • 2010
  • The widespread deterioration of concrete structures has required the development of new and innovative materials and technologies for strengthening and repair. Recently Fiber reinforced polymer(FRP) composites have received widespread attention as materials for the strengthening and repair of the deteriorated concrete structures. This paper presents the results of Fire-performance of RC beams strengthened with FRP-Aluminum composit hollow beams. Test results show that the higher-damaged FRP strengthened RC beams are more vulnerable to the fire and decrease the effect of FRP strenthening.

Development of CFS Jacketing Retrofit Method for Rectangular High Strength Concrete Columns by Cross Sectional Shape Modification (4각형 고강도 콘크리트 기둥 단면 변형을 통한 CFS Jacketing 보강방법 개발)

  • Lee, Jong-Gil;Kim, Jang-Ho Jay;Park, Seok-Kyun;Kim, Jin-Keun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.14 no.6
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    • pp.153-161
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    • 2010
  • Numerous past studies have shown that safety and serviceability of many concrete infrastructures and buildings built in 1970's have far less strength capacities than their original intended design capacities, thereby requiring repair and strengthening. Currently, aged concrete structures are being repaired using various methods developed in the past. Unfortunately, these methods do not consider the specific conditions that these members are under, but they merely attach repairing materials on the external surface for random strength improvements. Therefore, in order to improve repair and strengthening methods by considering composite behavior between repairing material and structural member, enhanced construction methodologies are needed. Also, the enhanced repairing and strengthening methods must be able to be implemented on structural members constructed using high performance concrete to meet the present construction demand of building mammoth structures. Therefore, in this study, a repairing and strengthening method for retrofitting high strength concrete (HSC) columns that can effectively improve column performance is developed. A square HSC column's cross-sectional shape is converted to an octagonal shape by attaching precast members on the surface of the column. Then, the octagonal column surface is surface wrapped using Carbon Fiber Sheets (CFS). The method allows maximum usage of confinement effect from externally jacketing CFS to improve strength and ductility of repaired HSC columns. The research results are discussed in detail.

Structural Performance of Reinforced Concrete Beams Strengthened with Sprayed Fiber Reinforced Polymers (Sprayed FRP로 보강된 철근콘크리트 보의 보강성능에 관한 연구)

  • Lee, Kang-Seok;Son, Young-Seon;Lee, Moon-Sung
    • Journal of the Korea Concrete Institute
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    • v.19 no.4
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    • pp.421-431
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    • 2007
  • The main purpose of this study is to develop a sprayed FRP repair and strengthening method, which is a new technique for strengthening the existing concrete structures by mixing one of the carbon or glass chopped fibers and one of the epoxy or vinyl ester resins with high-speed compressed air in open air and randomly spraying the mixture onto the concrete surface. At present, the sprayed FRP repair and strengthening method using the epoxy resin has not been fully discussed. In order to investigate the material property of the sprayed FRP, this study carried out tensile tests of the material specimens, which were changed with the combinations of various variables including the length of chopped fiber and the mixture ratio of chopped fiber and resin. These variables were set to have the equal material strength, compared with that of one layer of the FRP sheet. As a result, the optimal length of glass and carbon chopped fibers was fumed out to be 38 mm, and the optimal mixture ratio between chopped fiber and resin was also turned out to be 1 : 2 from each variable. And also, the thickness of the sprayed FRP to have the equal strength to one layer of the FRP sheet was finally calculated. In is study, a series of experiments were carried out to evaluate the strengthening effects of flexural beams, shear beams and damaged beams strengthened with the sprayed FRP method, respectively. The results revealed that the strengthening effects of the flexural and shear specimens were reasonably similar to those of the FRP sheet, and the developed Sprayed FRP technique is able to be used as a strengthening scheme of existing RC building.

Development of Underwater Adhesive, Epoxy, and FRP Composite for Repair and Strengthening of Underwater Structure (수중 구조물의 보수·보강을 위한 수중 접착제, 에폭시와 섬유복합재의 개발)

  • Kim, Sung-Bae;Yi, Na-Hyun;Nam, Jin-Won;Byun, Keun-Joo;Kim, Jang-Ho Jay
    • Journal of the Korea Concrete Institute
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    • v.22 no.2
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    • pp.149-158
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    • 2010
  • Recently, numerous construction techniques for repairing and strengthening methods for above ground or air exposed concrete structure have been developed. However repairing and strengthening methods for underwater structural members under continuous loading, such as piers and steel piles need the further development. Therefore, this study develops an aqua epoxy, which can be used for repairing and strengthening of structural members located underwater. Moreover, using the epoxy material and strengthening fibers, a fiber reinforced composite sheet called Aqua Advanced FRP (AAF) for underwater usage is developed. To verify and to obtain properties of the material and the performance of AAF, several tests such as pull-off strength test, bond shear strength test, and chemical resistance test, were carried out. The results showed that the developed aqua epoxy does not easily dissolve in wet conditions and does not create any residual particle during hardening. In spite of underwater conditions, it showed the superior workability, because of the high viscosity over 30,000 cps and adhesion capacity over 2 MPa, which are nearly equivalent to those used in dry conditions. In case of the chemical resistance test, the developed aqua epoxy and composite showed the weight change of about 0.5~1.0%, which verifies the superior chemical resistance.

Test on the strengthening effects and behavior of Roll beam with Stiffened carbon-plate (롤빔에 카본플레이트를 보강한 강재의 일체적거동 및 강성보강효과)

  • Sung, IkHyun
    • Journal of the Society of Disaster Information
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    • v.9 no.4
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    • pp.392-399
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    • 2013
  • The use of advanced composite materials in strengthening and repair of existing structures is increasing rapidly. One specific area in which the technique has been introduced lately is the strengthening of metallic structures with bonded carbon-fibre laminates. In this paper, the behaviors of composite steel-CFRP members is studied experimentally. A new type of test specimen has been developed for this purpose. By examining different combination of CFRP-laminates and adhesives, different types of fracture mode could be examined. The tested composite elements also displayed different behavior and a large difference in strength and ductility could be observed.