철근 콘크리트는 기반시설 건설과 각종 인프라 구축을 위해 가장 널리 사용되고 있는 재료이지만 시간의 경과에 따라 노후화가 진행되어 구조물의 성능저하 및 예상된 사용 수명이 단축된다는 문제점이 지적되고 있다. 이러한 문제점 중에는 과하중, 설계 및 시공결함등이 있어나 상당한 부분은 콘크리트 구조물이 오랜 기간동안 공기 중의 이산화탄소 등에 노출되어 콘크리트가 중성화되거나, 동절기 제설작업으로 살포되는 도로 제설제(deicing salt, CaCl2) 및 해양환경에 의한 염화물의 침투, 확산 등 유해요소로 인하여 철근이 부식되어 나타난 결과이다. 이를 보완하기 위하여 건설구조용 신소재로 연구되고 있는 대표적인 재료는 FRP(Fiber Reinforced Polymer 혹은 Plastic) Bar이다. FRP는 단위중량당 강도가 우수하여 구조물의 자중을 감소시킬 수 있고, 비부식성, 비전기성, 비전자성, 고인장강도 등의 성질로 취약한 환경조건에서의 내구성이 우수하여 건설재료로의 사용 가능성이 크다. 본 논문에서는 국내에서 생산된 FRP Bar를 휨 및 전단보강근으로 사용한 콘크리트 보에 대하여 휨 및 전단보강 FRP Bar의 종류, 휨보강량, 콘크리트의 압축강도수준 및 전단보강 유무에 따른 콘크리트 보의 ...
철근 콘크리트는 기반시설 건설과 각종 인프라 구축을 위해 가장 널리 사용되고 있는 재료이지만 시간의 경과에 따라 노후화가 진행되어 구조물의 성능저하 및 예상된 사용 수명이 단축된다는 문제점이 지적되고 있다. 이러한 문제점 중에는 과하중, 설계 및 시공결함등이 있어나 상당한 부분은 콘크리트 구조물이 오랜 기간동안 공기 중의 이산화탄소 등에 노출되어 콘크리트가 중성화되거나, 동절기 제설작업으로 살포되는 도로 제설제(deicing salt, CaCl2) 및 해양환경에 의한 염화물의 침투, 확산 등 유해요소로 인하여 철근이 부식되어 나타난 결과이다. 이를 보완하기 위하여 건설구조용 신소재로 연구되고 있는 대표적인 재료는 FRP(Fiber Reinforced Polymer 혹은 Plastic) Bar이다. FRP는 단위중량당 강도가 우수하여 구조물의 자중을 감소시킬 수 있고, 비부식성, 비전기성, 비전자성, 고인장강도 등의 성질로 취약한 환경조건에서의 내구성이 우수하여 건설재료로의 사용 가능성이 크다. 본 논문에서는 국내에서 생산된 FRP Bar를 휨 및 전단보강근으로 사용한 콘크리트 보에 대하여 휨 및 전단보강 FRP Bar의 종류, 휨보강량, 콘크리트의 압축강도수준 및 전단보강 유무에 따른 콘크리트 보의 전단특성을 일반적인 철근 콘크리트와의 비교․검토하고, FRP Bar 콘크리트에서의 전단보강효과 연구에 대한 기초적 자료를 제공하고자 한다.
철근 콘크리트는 기반시설 건설과 각종 인프라 구축을 위해 가장 널리 사용되고 있는 재료이지만 시간의 경과에 따라 노후화가 진행되어 구조물의 성능저하 및 예상된 사용 수명이 단축된다는 문제점이 지적되고 있다. 이러한 문제점 중에는 과하중, 설계 및 시공결함등이 있어나 상당한 부분은 콘크리트 구조물이 오랜 기간동안 공기 중의 이산화탄소 등에 노출되어 콘크리트가 중성화되거나, 동절기 제설작업으로 살포되는 도로 제설제(deicing salt, CaCl2) 및 해양환경에 의한 염화물의 침투, 확산 등 유해요소로 인하여 철근이 부식되어 나타난 결과이다. 이를 보완하기 위하여 건설구조용 신소재로 연구되고 있는 대표적인 재료는 FRP(Fiber Reinforced Polymer 혹은 Plastic) Bar이다. FRP는 단위중량당 강도가 우수하여 구조물의 자중을 감소시킬 수 있고, 비부식성, 비전기성, 비전자성, 고인장강도 등의 성질로 취약한 환경조건에서의 내구성이 우수하여 건설재료로의 사용 가능성이 크다. 본 논문에서는 국내에서 생산된 FRP Bar를 휨 및 전단보강근으로 사용한 콘크리트 보에 대하여 휨 및 전단보강 FRP Bar의 종류, 휨보강량, 콘크리트의 압축강도수준 및 전단보강 유무에 따른 콘크리트 보의 전단특성을 일반적인 철근 콘크리트와의 비교․검토하고, FRP Bar 콘크리트에서의 전단보강효과 연구에 대한 기초적 자료를 제공하고자 한다.
It is pointed out as a pending issue today that the corrosion of steel reinforcing bar reduces the service life of reinforced concrete structures. Especially, in the territory with cold weather, sizeable amounts of Calcium Chloride are used to remove snow and ice, so the corrosion problem of deforme...
It is pointed out as a pending issue today that the corrosion of steel reinforcing bar reduces the service life of reinforced concrete structures. Especially, in the territory with cold weather, sizeable amounts of Calcium Chloride are used to remove snow and ice, so the corrosion problem of deformed bar becomes very serious.
In case of domestic reinforced concrete structures with steel deformed bar, corrosion of steel deformed bar appeared with the approximate degree of 15% in the floor plates of concrete bridges located on the highways and urban area as well as those located in the oceanic environments.
In order to prevent such corrosion of deformed bar, countermeasures such as usage of epoxy coated deformed bar, restriction of cracked gap in the service load states, usage of latex treated concrete, and increase of coating thickness, etc. are necessary. Recently researches on the application of FRP(Fiber Reinforced Polymer) bar materials have emerged as a practical alternative material for producing reinforcing bars for concrete structures. FRP Bars offer advantages over steel reinforcement in the points that FRP Bars are noncorrosive, and some FRP Bars are nonconductive. Due to other differences in the physical and mechanical behavior of FRP materials versus steel, unique guidance on the engineering and construction of concrete structures reinforced with FRP Bars is needed. Several countries, such as Japan, Canada, and USA, have already established design and construction guidelines specifically for the use of FRP Bars as concrete reinforcement.
This paper suggests fundamental informations on the shear characteristics of concrete beams reinforced with FRP Bars instead of steel reinforcements. In order to evaluate characteristics, various tests were executed and test results were analysed. The fundamental data for the design standard of FRP Bar concrete beam which meets the real situation in our country are suggested. Experimental parameters used are types of FRP Bar, amount of flexural reinforcement, and strength level of concrete. In this paper, three kinds of FRP Bars were used, i.e., CFRP(Carbon Fiber Reinforced Polymer), GFRP(Glass Fiber Reinforced Polymer), and HFRP(Hybrid Fiber Reinforced Polymer). The shear strength of concrete were estimated after having used these FRP Bars flexural reinforced bar in the concrete beams.
In addition, FRP Bar was used as a shear-reinforced bar having assembled in rectangular shape. Then it was compared to the shear force contribution of the concrete beam that is shear-reinforced by deformed bar, and thereby the possibility to use FRP Bar as shear reinforced bar was examined.
Results of experiment and analysis, shear strength equation by ACI 318 overestimated the shear strength, and ACI 440 underestimated. So, shear strength equations are modified by multiplied shear correction factors. Shear correction factors are formulated various functions with reinforcing ratio, ultimate strain of FRP Bars, and ultimate strength ratio FRP Bars to steel reinforcement. In case of concrete beams reinforced with FRP Bars, there were trend that increasing shear strength of concrete beams, as increasing flexural reinforcement ratio. And, shear strength equation by specifications overestimated the shear strength of high strength concrete compared with normal strength concrete. Therefore in order to correct shear strength, shear strength constant were suggested considering strength level of concrete.
Futhermore, in order to design and to construct FRP Bar concrete structure rationally and safely, it is necessary advanced researches considering types of FRP Bar, amount of shear reinforcement, variation of shear span, and effective depth of beam, etc.
It is pointed out as a pending issue today that the corrosion of steel reinforcing bar reduces the service life of reinforced concrete structures. Especially, in the territory with cold weather, sizeable amounts of Calcium Chloride are used to remove snow and ice, so the corrosion problem of deformed bar becomes very serious.
In case of domestic reinforced concrete structures with steel deformed bar, corrosion of steel deformed bar appeared with the approximate degree of 15% in the floor plates of concrete bridges located on the highways and urban area as well as those located in the oceanic environments.
In order to prevent such corrosion of deformed bar, countermeasures such as usage of epoxy coated deformed bar, restriction of cracked gap in the service load states, usage of latex treated concrete, and increase of coating thickness, etc. are necessary. Recently researches on the application of FRP(Fiber Reinforced Polymer) bar materials have emerged as a practical alternative material for producing reinforcing bars for concrete structures. FRP Bars offer advantages over steel reinforcement in the points that FRP Bars are noncorrosive, and some FRP Bars are nonconductive. Due to other differences in the physical and mechanical behavior of FRP materials versus steel, unique guidance on the engineering and construction of concrete structures reinforced with FRP Bars is needed. Several countries, such as Japan, Canada, and USA, have already established design and construction guidelines specifically for the use of FRP Bars as concrete reinforcement.
This paper suggests fundamental informations on the shear characteristics of concrete beams reinforced with FRP Bars instead of steel reinforcements. In order to evaluate characteristics, various tests were executed and test results were analysed. The fundamental data for the design standard of FRP Bar concrete beam which meets the real situation in our country are suggested. Experimental parameters used are types of FRP Bar, amount of flexural reinforcement, and strength level of concrete. In this paper, three kinds of FRP Bars were used, i.e., CFRP(Carbon Fiber Reinforced Polymer), GFRP(Glass Fiber Reinforced Polymer), and HFRP(Hybrid Fiber Reinforced Polymer). The shear strength of concrete were estimated after having used these FRP Bars flexural reinforced bar in the concrete beams.
In addition, FRP Bar was used as a shear-reinforced bar having assembled in rectangular shape. Then it was compared to the shear force contribution of the concrete beam that is shear-reinforced by deformed bar, and thereby the possibility to use FRP Bar as shear reinforced bar was examined.
Results of experiment and analysis, shear strength equation by ACI 318 overestimated the shear strength, and ACI 440 underestimated. So, shear strength equations are modified by multiplied shear correction factors. Shear correction factors are formulated various functions with reinforcing ratio, ultimate strain of FRP Bars, and ultimate strength ratio FRP Bars to steel reinforcement. In case of concrete beams reinforced with FRP Bars, there were trend that increasing shear strength of concrete beams, as increasing flexural reinforcement ratio. And, shear strength equation by specifications overestimated the shear strength of high strength concrete compared with normal strength concrete. Therefore in order to correct shear strength, shear strength constant were suggested considering strength level of concrete.
Futhermore, in order to design and to construct FRP Bar concrete structure rationally and safely, it is necessary advanced researches considering types of FRP Bar, amount of shear reinforcement, variation of shear span, and effective depth of beam, etc.
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