• Magazine of the Korea Concrete Institute
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• v.9 no.5
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• pp.177-187
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• 1997

철근 콘크리트 구조부재는 철근과 콘크리트로 구성된 합성부재이므로, 철근콘크리트 구조부재의 피로강도는 철근과 콘크리트 고유의 피로특성에 따라 변화하게 된다. 철근자체의 피로특성은 철근의 정적강도 특성과 상이함으로, 실험을 통하여 규명할 필요가 있다. 본 논문에서는 대표적인 국내 2개사에서 생산되는 철근에 대하여 직접인장 피로실험을 실시하여 이들의 피로특성을 규명하였으며, 철근콘크리트 휨부재 내부의 철근 피로특성과 철근만의 직접인장 피로특성의 비교 분석으로부터 직접인장 피로실험만으로 철근콘크리트 휨부재의 피로특성을 평가할 수 있음을 밝혔다. 또한 반복하중을 받는 철근콘크리트 부재의 피로점토를 위한 기준을 제시하였다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.6
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• pp.1-9
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• 2017

Spiral reinforcement in a circular column plays an effective role in the ductile behavior of a column through position fixing and buckling restraining of the longitudinal reinforcement, and confining core-concrete. Each country has suggested the minimum volumetric ratio of spiral reinforcement in order to secure the ductility of concrete columns. The minimum volumetric ratio of spiral reinforcement suggested by ACI 318-14 and the national concrete structure design standard was developed based on the theory of Richard et al. (1928); furthermore it has been used until now. However, their theory cannot consider the effects of high strength concrete and high strength reinforcement, and arrangement condition of the spiral reinforcement. In this study, a modified minimum volumetric ratio equation is suggested, which is required to improve the ductility of reinforced concrete circular columns and to recover their stress. The modified minimum volumetric ratio equation suggested here considers the effect of the compressive strength of concrete, the yield strength of spiral reinforcement, the cross sectional area of columns, the pitch of spiral reinforcements and the diameter of spiral reinforcement. In this paper, the validity of the minimum volumetric ratios from ACI 318-14 and this study was investigated and compared based on the results of uniaxial compression experiment for specimens in which the material strength and the spiral reinforcements ratio were used as variables. In the end of the study, the modification method for the suggested equation was examined.

• Journal of the Korean Society of Hazard Mitigation
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• v.3 no.3 s.10
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• pp.143-150
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• 2003

Recently, The corrosions of reinforced concrete structures are severe problems of economical social effects. PE-coated bars protecting from corrosion and enhancing durability of reinforced concrete structures are testified to evaluate structural properties. Tests are verified by comparative bending tests of the three type materials of epoxy coating, without coating and pe-coating. Load-deflection relations ate superior in pe-coated bar than any other materials(bare bar and epoxy bar). These are proved bonding properties enhancement by using cement powder.

• Journal of the Korea Concrete Institute
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• v.26 no.3
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• pp.299-306
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• 2014

Coating is one of the methods used to solve the problem of corrosion of reinforcement in concrete structures. There are few research reported in the literature regarding the effect of zinc-coating on flexural behavior compared to epoxy coating. The objective of this study was to determine whether zinc-coated rebar adversely affects flexural behavior. Concrete beams reinforced with black or zinc-coated steel were tested in flexure. The test variables included the presence of rebar surface coating with zinc, steel ratio used and cover depth. The study concentrated on comparing crack pattern, crack width, deflection and strain. The ultimate flexural capacity of beams reinforced with zinc-coated bars was not different from that of black steel reinforced beams. The results from deflection and crack width measurements were indicative of no significant variation for the different rebar surface conditions. In addition, it was found that load-strain curve of beam reinforced with zinc-coated steel was similar to that of beam reinforced with zinc-coated steel. Therefore, the test results indicated that the use of zinc-coated rebar had no adverse effect on flexural behavior compared to the use of black rebar.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.61-64
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• 2008

Reinforced Concrete structures are constructed under the basic assumption of perfect bonding between steel and concrete. The corrosion of steel in the reinforced concrete columns results in the excessive cracks and gradual deterioration of concrete between steel and concrete. The cyclic loading test was conducted with the three corrosion rates in the laboratory. Throughout this test, it is investigated a bond behavior of reinforced concrete columns under a steel corrosion. Main variables of the test are a corrosion of steel reinforcement and a level of stress.

• Journal of the Korea Concrete Institute
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• v.16 no.5 s.83
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• pp.635-643
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• 2004

In this study, the tensile strength of 321 full-sized grout-filled splice steeve specimens were compared and analyzed in order to afford the data for a reasonable and economical design of this system. The experimental variables analyzed in this study were embedment length of reinforcing bars, compressive strength of grout, sleeve geometry, loading pattern and final failure mode of specimen. Following main conclusions are obtained : 1) The strength of grout-filled splice sleeve tends to be improved with increasing compressive strength of grout and embedment length of reinforcing bars. Specially this tendency appears apparent in specimens of bond failure rather than rebar failure. 2) The results of this study show that the sleeve geometry have influence on the bond strength of grout-filled splice sleeve. 3) The grout-filled splice sleeve of bond failure don't show the difference of tensile strength according to size of rebar. 4) It is verified that the tensile strength required in ACI and domestic code is retained either when the compressive strength of grout over 70 MPa is used with embedment length of reinforcing bars over 4.5d or when the compressive strength of grout over 80 MPa is used with embedment length of rebars over 3.9d. 5) It is verified that the tensile strength required in AIJ code is retained in case when the embedment length of reinforcing bars is 0.8 times the rebar diameter longer than in ACI code.

• Magazine of the Korea Concrete Institute
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• v.10 no.2
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• pp.119-126
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• 1998

본 연구는 철근비와 보강판비를 조정한 보강철근비를 변수로 탄소섬유쉬트 접착된 철근콘크리트 보에 대하여 그 변형특성과 강도특성 및 파괴모드를 실험적으로 고찰한 것이다. 철근비와 보강판비가 증가할수록 최대내력은 증가하는 경향을 보이지만 탄소섬유쉬트의 겹수가 증가할수록 철근비 증가의 경우와는 달리 에너지흡수능력이 저하된다. 철근비와 보강판비에 따른 파괴모드를 구분하고 시험결과와 비교, 고찰하였던 바 파괴모드와 연성의 측면에서 보강철근비 е의 한계값을 0.87 max으로 제안하였다．탄소섬유쉬트와 철근콘크리트 보의 합성작용이 철근항복이후까지 유지되어 비선형적인 거동을 보임으로써 구조적거동이 양호하게 나타나는 것으로 입증되었다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.529-532
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• 2010

본 연구에서는 철근가격 급등과 배근시공도 작성 인력 부족에 대비하여 SDM# 제품군을 사용하여 이음/정착을 고려한 3차원 철근 배근 자동화 기술(RAP)로 철근 배근 자동생성 및 배근시공도 작성 시스템을 개발하였다. 최근 철근가격 급등으로 인한 공사원가상승/인건비 상승/배근시공도 작성 인력 부족 등의 기존현황의 문제점 등을 SDM# 제품군의 철근 배근 자동화 기술(RAP)을 이용하여 자동 철근배근/배근시공도 작성/정밀 골조물량 산출/인력절감/시공 정밀도 향상/골조 공사비 절감 등의 효과와 기존의 현장가공으로 인한 철근 손실률 8%를 공장가공을 적용함으로써 3% 수준으로 낮출 수 있어 5% 내외의 절감효과를 얻을 수 있다. 철근현장가공에서 공장가공 전환으로 골조물량 절감을 기대할 수 있고, 이음/정착/응력분포가 고려된 3차원 철근 배근 자동화 기술(RAP)을 이용하여 자동배근 알고리즘에 의한 배근시공도/가공도 작성 효율을 높이고, 기술 자립을 통해 건설시공 분야의 기술력 향상을 기대할 수 있다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.1
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• pp.27-34
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• 2012

The objective of this study is to evaluate the stiffness of mortar-filled sleeve bar splice using estimation method of failure mode in the sleeve reinforcement splice. To attain this goal, we analyzed the test results of 261 actual-sized mortar-filled sleeve splice specimens. The study results showed that the estimation method of the failure mode in mortar-filled sleeve bar splice made an effective estimate of the stiffness in this bar splice with the exception of specimens with SD500 bars and smooth pipe sleeve. Especially, of the specimens with cast sleeve or uneven pipe sleeve in the range of reinforcement fracture using the estimation method of the failure mode in mortar-filled sleeve splice, specimens over 98% with SD400 bars and all specimens with SD500 bars had the stiffness capacity of higher than "A" class of AIJ code in monotonic loading. In addition, of the specimens in the range of reinforcement fracture using the estimation method of the failure mode in mortar-filled sleeve splice, all specimens with SD400 bars and SD500 bars had the stiffness capacity of higher than "A" class of AIJ code in cyclic loading.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2015.07a
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• pp.213-215
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• 2015

플로팅 건축용 콘크리트 구조물은 부식환경에 노출되어 매립된 철근의 부식에 따른 구조물의 내구성능에 문제가 발생하게 된다. 철근 부식에 의한 내구성이 저하되는 문제의 여러 효과적인 해결방법 중 하나로 철근 코팅 기법이 있으며, 철근의 용융아연도금시 표면에 용융아연층이 형성되어 철근을 보호하는 장점이 있으나 콘크리트와의 부착 성능에 대한 연구는 미비한 실정이다. 따라서, 본 연구에서는 플로팅 건축용 콘크리트 구조물의 철근 겹이음에 따른 거동 특성연구를 수행하였다.