• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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• pp.323-326
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• 2005

Uniaxial tension test of Glass Fiber Reinforced Polymer (GFRP) bar reinforced concrete prisms was performed. The objective was to investigate the adequate cover thickness of the GFRP rebars. The tension stiffening effect of GFRP bar reinforced concrete was also studied. The test variables included rebar types (conventional steel rebar and two different GFRP rebars) and cover thicknesses (five different cover thicknesses ranging between 1-3db). Normal strength concrete was used. Cracking patterns on concrete surface and cracking loads were careful1y observed during the direct tensile test. The test results indicated that the adequate cover thickness of the GFRP rebars may even be larger than that of the steel rebars and that the cover thickness of 2db commonly specified for the GFRP rebars may not be large enough. The tension stiffening effect of the GFRP rebars was also quantified and documented from the test results.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.73-74
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• 2023

The purpose of this study is to derive the cause of the quantity difference and present the considerations when take-off rebar quantity based on BIM model by comparing the quantity of rebar based on BIM model with 2D drawing. This research was limited to take-off the quantity of rebars in the building frame work, and after take-off the quantity of rebars by 3D modeling the 2D drawing of the target building with Revit, the quantity difference was compared with 2D-based software. Therefore, when take-off the quantity of rebars based on the BIM model, instead of take-off the existing 2D-based quantity premium proportion, according to general structural consider development length, lap splice length, covering thickness, reinforcing bars and spacing. In the future, this study is expected to contribute to improving the accuracy of BIM-based frame construction quantity take-off.

• Journal of Advanced Marine Engineering and Technology
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• 제40권2호
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• pp.107-111
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• 2016

This paper presents electrochemical corrosion behaviors of cement mortar specimens in the high salinity condition. Chloride ion is known as the most detrimental parameter to cause the corrosion in reinforced concrete. Increasing the concrete cover thickness is one of the corrosion protection methods against chloride ion; so, this study mainly focuses on the effects of mortar cover thickness on corrosion protection. In specimens, rebar, which was a height of 200 mm and a diameter of 10 mm, was installed at the center of the small size form. Later on, mortar was injected into the form, and 10, 20, 30, 40, and 50 mm of the different mortar cover thicknesses were selected. Potential measurements, linear polarization resistance tests, and cyclic potentiodynamic polarization tests were performed for specimens that were exposed to seawater. These results were compared with visual inspection results of rebar. The results show that an increase in the cover thickness contributes to corrosion protection. In addition, the result of electrochemical corrosion tests generally agreed with that of an autopsy visual inspection.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.248-251
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• 2004

This study was performed to propose the minimum thickness of RC slab that satisfies constructibility, fatigue safety, and serviceability requirements such as deflection control. Three different minimum thicknesses are calculated using concrete shear and rebar fatigue formulas, and deflection control, respectively, and checked by constructiblity. The maximum of these three minimum thicknesses is proposed as the minimum thickness of RC slab, which shows that the minimum thickness requirement of RC slab from Korean Bridge Design Code can be thinner than now.

• 토지주택연구
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• 제7권1호
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• pp.53-63
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• 2016

본 논문은 옥상녹화하중 세 가지 유형(경량형, 중량형, 혼합형)이 한국토지주택공사(이하 LH)에서 공급하는 공동주택과 부대복리시설의 옥상층 슬래브에 미치는 영향을 구조해석과 설계를 통해 평가하고, 이를 토대로 옥상녹화하중이 작용하는 옥상층 슬래브의 구조설계시 활용가능한 배근 가이드 라인을 제시하였다. 구조해석 및 설계결과, 옥상녹화하중의 종류에 관계없이 LH 공동주택의 옥상층 슬래브는 슬래브 주근을 D10 철근 200~250mm 간격으로 배근할 경우 안전하며, 슬래브 두께도 150mm로 적용가능한 것으로 나타났다. 콘크리트 설계강도가 24, 27, 30MPa로 변화하여도 옥상층 슬래브의 슬래브 주근은 D10 철근을 200~250mm 배근하고 슬래브 두께도 150mm가 적용가능한 것으로 나타났다. 옥상녹화하중이 작용하는 부대복리시설의 2방향 슬래브는 토양 종류와 토심 두께에 관계없이 D10철근을 200mm 간격으로 배근하고 슬래브 두께도 150mm로 적용가능한 것으로 나타났다.

• Steel and Composite Structures
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• 제20권1호
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• pp.71-89
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• 2016

In steel and concrete composite girders, the load transfer between the steel beam and the concrete slab is commonly ensured by installing shear connectors. In this paper, to investigate the nonlinear behavior of perfobond connectors, a total of 60 push-out specimens were fabricated and tested with the variables for the hole diameter, the concrete strength, the thickness of concrete slab, the diameter, strength and existence of perforating rebar, the thickness, height and distance of perfobond ribs. The failure mode and the load-slip behavior of perfobond connectors were obtained. A theoretical model was put forward to express the load-slip relationship. Analytical formulas of shear capacity and peak slip were also proposed considering the interaction between the concrete dowel and the perforating rebar. The calculation results of the proposals agreed well with the experimental values.

• 한국안전학회지
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• 제30권6호
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• pp.70-77
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• 2015

In this study, the governing design factors of GFRP-reinforced concrete bridge deck are analyzed for typical bridges in Korea. The adopted bridge deck is a cast-in-situ concrete bridge deck for the prestressed concrete girder bridge with dimensions of 240 mm thickness and 2.75 m span length from center-to-center of supporting girders. The selected design variables are the diameters of GFRP rebar, spacings of GFRP rebars and concrete cover thicknesses, Considering the absence of the specification relating GFRP rebar in Korea, AASHTO specification is used to design the GFRP-reinforced concrete bridge deck. The GFRP-reinforced concrete bridge deck is proved to be governed by the criteria about serviceability, especially maximum crack width, while steel reinforced concrete bridge deck is governed by the criteria on ultimate limit state. In addition, GFRP rebars with diameter of 16 mm ~ 19 mm should be used for the main transverse direction of decks to assure appropriate rebar spacings.

• Computers and Concrete
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• 제23권1호
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• pp.69-80
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• 2019

Modeling approach for mesoscopic model of concrete depicting mass transportation and physicochemical reaction is important since there is growing demand for accuracy and computational efficiency of numerical simulation. Mesoscopic numerical simulation considering binder, aggregate and Interfacial Transition Zone (ITZ) generally produces huge number of DOFs, which is inapplicable for full structure. In this paper, a three-dimensional multiscale approach describing three-phase structure of concrete was discussed numerically. An effective approach generating random aggregate in polygon based on checking centroid distance was introduced. Moreover, ITZ elements were built by parallel expanding the surface of aggregates on inner side. By combining mesoscopic model including full-graded aggregate and macroscopic model, cases related to diffusivity and thickness of ITZ, volume fraction and grade of aggregate were studied regarding the consideration of multiscale compensation. Results clearly showed that larger analysis model in multiscale model expanded the diffusion space of chloride ion and decreased chloride content in front of rebar. Finally, this paper addressed some worth-noting conclusions about the chloride distribution and rebar corrosion regarding the configuration of, rebar diameter, concrete cover and exposure period.

• Steel and Composite Structures
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• 제52권2호
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• pp.165-182
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• 2024

Grouted sleeve splice (GSS) is an effective type of connection applied in the precast concrete structures as it has the advantages of rapidly assembly and reliable strength. To decrease the weight and cost of vertical rebar connection in precast shear walls, a light-weight sleeve is designed according to the thick-cylinder theory. Mechanical behaviour of the light-weighted GSS is investigated through experimental analysis. Two failure modes, such as rebar fracture failure and rebar pull-out failure, are found. The load-displacement curves exhibit four different stages: elastic stage, yield stage, strengthening stage, and necking stage. The bond strength between the rebar and the grout increases gradually from outer position to inner position of the sleeve, and it reaches the maximum value at the centre of the anchorage length. A finite element model predicting the mechanical properties of the light-weighted GSS is developed based on the Concrete Damage Plasticity (CDP) model and the Brittle Cracking (BC) model. The effect of the rebar anchorage length is significant, while the increase of the thickness of sleeve and the grout strength are not very effective. A model for estimating ultimate load, including factors of inner diameter of sleeves, anchorage length, and rebar diameter, is proposed. The proposed model shows good agreement with various test data.

• 한국안전학회지
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• 제27권5호
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• pp.95-98
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• 2012

There are many high-rise apartment building construction in Korea. There was an accident to pass through worker head by rebar dropped from height place. Therefore, low cost-high effectiveness method to prevent this type of accident should be revised and applied into the construction site. This study is to find out which method could be effectively applied to a site with low cost. Practical field test at 4th floor, 10th floor of apartment building site using re-bar diameter D10, D13, D16, D19, D22 with a length of 1 m, 1.5 m, 2 m, 2.5 m, 3 m which are common by used in a site. The test has also been done with a cover of styrofoam thickness 4.5 cm and thickness 9cm on field drop preventing net. One sheet of styrofoam thickness 45 mm has approximately two times stronger than only prevention net, It is found. Also, Two sheets have approximately two times stronger than one sheet of it.