이 논문의 목적은 압축강도 130 MPa급의 고강도 강섬유 보강 콘크리트 보의 휨거동 특성을 파악하는데 있다. 부피비 1.0%의 강섬 유와 철근비 0.02 이하의 철근으로 보강된 고강도 강섬유 보강 콘크리트의 휨거동 특성 실험결과를 제시하였다. 일반강도철근과 고강도철근 을 실험 부재에 사용하였다. 강섬유 보강 콘크리트의 압축 및 인장거동 재료 실험과 모델링을 수행하였다. 강섬유 보강 콘크리트의 하중-균열 개구변위 실험결과를 반영하여 가상균열모델에 근거한 역해석을 통해 인장거동모델링을 제시하였다. 실험결과는 강섬유 보강 콘크리트와 고 강도철근의 사용은 균열제어 및 연성 거동에 유리한 것을 나타낸다. 일반강도철근을 사용한 보의 휨강도 실험값에 대한 수치해석에 의한 예측 값의 비는 0.81~1.42를 나타내고, 고강도철근을 사용한 보의 휨강도 실험값에 대한 수치해석에 의한 예측값의 비는 0.92~1.07을 나타낸다. 수 치해석에 의한 휨강도는 실험결과를 합리적으로 예측하고 있는 것으로 판단된다.

Reinforced concrete hume pipes have been widely used as drain pipes. However, many reinforced concrete hume pipes are exposed to the deteriorated environments such as freezing-thawing damage, chemical attack and chloride ion immersion by using sea sand. The purpose of this study is to improve the durability of reinforced concrete hume pipe by using the polymer cement slurry(PCS)-coated rebar and treating the surface by polymer cement mortar(PCM). From the test results, it is apparent that PCS-coated rebar has a excellent resistance to chloride ion penetration and the PCM has good mechanical properties and durability as a lining material for reinforced concrete hume pipe product.

This paper introduces the recent development of GFRP-steel hybridized rebar and deals with an evaluation of its mechanical performance by authors. The objective of this study is to investigate tensile and bonding performance of the GFRP-steel hybridized rebar. The effect of hybridization on tensile properties was evaluated by comparing the results of tensile test with those of non-hybrid GFRP bars. The surface of the bar was designed and experimentally evaluated to obtain the sufficient bond strength in this study. To ensure the long-term durability of GFRP-steel hybridized rebar to corrosion resistance, the individual and combined effects of environmental conditions are currently under investigation.

In this study, Corrosion behavior in mortar was observed by the passage of time by using EIS method. As a result of EIS experiment, equivalent circuit and changes of Impedance parameter could be observed. In addition, it was confirmed that impedance of rebar in mortar and corrosion rate according to the amount of NaCl were different.

Accelerated alkali resistance test were conducted for pre-heated GFRP Rebar. The GFRP rebar specimens were heated to temperatures of 60℃, 120℃, 200℃ and 300℃ and then immerged in alkali solution for 30days. According to ACI 440.3R-12, tensile properties were measured.

It is necessary to develop application design technology and modular of reinforcing bar. After reviewing the rebar drawing of the NPP Stucture and performing the mock-up test, the rebar modularization method in the various area of the NPP Stucture has been established.

It is necessary to develop application design technology and modular of reinforcing bar. After reviewing the rebar drawing of the NPP Stucture and performing the mock-up test, the rebar modularization method in the various area of the NPP Stucture has been established.

Bond strength of PCS-coated rebar is better than that of uncoated rebar and epoxy-coated rebar. It is also high bond strength at curing ages of 7-day or less, and coating thicknesses of 75 μm and 100 μm. The maximum bond strength of PCS-coated rebar at curing age of 3-hour is almost same as that of curing age of 1-day and 7-day. The maximum bond strength of PCS-coated rebar with EVA at polymer-cement ratio of 100%, and coating thickness of 100 μm is about 1.23 and 1.29 times respectively, the strength of uncoated rebar and epoxy-coated rebar. It is apparent that the curing age, coating thickness and polymer cement ratio are very important factors to improve the bond strength of PCS-coated rebar to cement concrete. We can havebasic information that it can replace epoxy coated rebar by the PCS-coated rebar with curing age at 3-hour and coating thickness of 100 μm.

용융아연도금(galvanizing)은 콘크리트 구조물의 철근 부식 문제를 해결하기 위해 사용된다. 용융아연도금 철근 콘크리트 보의 부착강도 영향에 대한 자료는 거의 없는 실정이다. 따라서, 이 연구의 목적은 용융아연도금철근이 콘크리트 보의 부착강도에 미치는 영향을 파악하는 데 있다. 용융아연도금철근을 사용한 부재와 일반철근을 사용한 부재의 구조실험을 통하여 겹침이음 거동과 부착강도 특성을 비교하였다. 실험변수로써 철근의 용융아연코팅 유무, 철근 직경과 겹침이음 길이를 고려하였다. 용융아연도금 철근콘크리트 보의 균열 및 파괴 특성을 파악하였다. 용융아연도금철근 콘크리트 보의 겹침이음부 휨 거동특성은 일반철근 콘크리트 보의 겹침이음부 휨거동과 유사한 것으로 나타난다. 또한, 용융아연도금철근의 사용은 일반철근을 사용할 때에 비해 콘크리트 보의 부착강도에 불리한 영향을 미치지는 않는 것으로 나타났다.

In this study, longitudinal strain distribution of spliced rebar in the 1-directional tension test are evaluated with an image processing method (IPM). From these results, it is estimated that the coupler can decrease the elongation at the ultimate load, therefore, the spliced rebar with coupler should be evaluated to be used in the RC structure with LSD.

In this study, longitudinal strain distribution of rebar in the 1-directional tension test are evaluated with an image processing method (IPM). From these results, it is estimated that the necking region can make the over estimation of elongation of rebar, therefore, the estimation except the necking region can be suggested to evaluate the true elongation of rebar.

The ultimate load of beam reinforced with polymer cement slurry(PCS)-coated rebar that is developed to replace the epoxy coated rebar having many defects is almost the same as that using plain rebar, and is higher than that of epoxy-coated rebar. In special, that using EVA 100% with ultra high early strength cement is a little bigger than that using plain rebar. In this study, it is also apparent that PCS-coated rebar can replace epoxy-coated rebar to solve the corrosion problem in marine construction field.

This study was performed to analyze the flexural performance of large diameter PHC Pile reinforced with transveres and longitudinal rebar and in-filled concrete. From the flexural test result, it was found that the initial cracking strength and maximum flexural strength of composite PHC pile were approximately 400% and 345% higher than that of the conventional PHC pile.

In general, polymer cement slurry(PCS) that is made from organic polymer dispersion and cement has good adhesion to steel and cement concrete. Bond strength of PCS-coated rebar is better than that of plain rebar and epoxy-coated rebar. The maximum bond strength of PCS-coated rebar at curing age of 1-day or 3-hour is almost same as that of curing age of 7-day and 28-day. It is possible that PCS-coated rebar with coating thickness of 100㎛ at curing age of 1-day and 3-hour can replace epoxy-coated rebar. It is also apparent that the choice of curing age and coating thickness is very important to improve the bond strength of PCS-coated rebar to cement concrete.

In reinforced concrete structure, rebar connection method should be considered because of its structural role to resist the tensile stress and its structural load transmission with concrete in the concrete structure. Lapped splice and mechanical sleeve type connector have been traditionally used to connect rebar in the concrete structures. In this study, to examine the mechanical and failure behaviors of rebar bar connected by taper type coupler in the concrete member depending on connection type and condition, tensile tests of steel rebar with taper type coupler and flexible loading tests of concrete beams were conducted. Its tensile strength and flexible strength of the rebar connected by taper type coupler were compared and evaluated by mechanical behaviors of rebar. From this study, steel rebar connected by taper type coupler showed it has similar mechanical performance comparing with unconnected rebar, thus taper type coupler can be used in the rebar fabrication of reinforced concrete structure.

This study takes shear wall of reinforced concrete structure as study object, and the purpose of this study is to suggest structure BIM based on automatic reinforcing bar placement system applying set-based design through the most optimum reinforcing bar placement group that was selected by applying AHP (analytical hierarchy process) method from design step. For this, the most optimum reinforcing bar placement group was selected by pairwise comparison analysis on complex standard of multiple alternatives. And shear wall automatic reinforcing bar placement system has been developed, which can automatically generate members and arrange reinforcing bar by structure design algorithm and using open API (application programming interface) provided by a BIM software vendor. As a result, the most optimum reinforcing bar placement group of the highest weight, ALT1, was selected and was generated using Tekla Structure program.

GFRP 보강근의 역학적 성능은 고온과 콘크리트의 알칼리 환경에서 크게 감소된다. 본 연구에서는 GFRP 보강근이 열손상 뒤, 알칼리 환경에 추가로 노출되었을 때의 계면전단강도변화를 고찰하는데 집중하였다. 이를 위하여 GFRP 보강근 시편은 270도의 열에 1시간동안 노출된 후 알칼리 용액에 장기간 노출되었으며, 전단시험에 의하여 파괴되었다. 비교를 위하여 열손상이 없는 시편도 같은 기간 동안 알칼리 용액에 노출된 후 전단에 의하여 파괴되었다. 결과에서, 열손상을 받은 GFRP보강근의 계면전단강도의 감소가 열손상이 없는 보강근 보다 훨씬 큰 것으로 나타났다. 본 실험을 근거로 하여, 열손상을 미리 받은 GFRP 보강근이 알칼리에 노출되었을 때, 장기 잔존계면전단강도의 예측을 위한 2차식을 제시하였다.

Integral abutment bridges (IABs) have been used only as short to medium long bridges because thermal displacements of IABs limit the bridge length. One of recent studies regarding IABs showed the use of a spiral rebar can effectively control the crack propagations of the pilecap (Frosch, 2009). Accordingly, in this study, parametric study of spiral rebar on pile-to-pilecap connection were performed.

Mechanical splice sleeve has bee used to join the reinforcement rebar for transmitting stress effectively and guaranteeing mechanical performance of the reinforcement rebar which has been segmentally made. In this study, tensile strength of the embedded reinforcement rebar joined by splice sleeve were examined to evaluate the mechanical behavior and effect on tensile strength of the rebar joined by splice sleeve in the concrete member depending on rebar joining condition.