직교이방향 이층 유리섬유 강화 Epoxy 수지를 사용하여 인장축에 대해 섬유방향이 0˚, 15˚, 25˚ 및 45˚인 시료로 인장시험 및 전기절연 강도시험을 통하여 얻은 결과는 다음과 같다. 1) 섬유방향이 인장축에 대해 0˚에서 45˚로 증가함에 따라 항복응력 및 파단응력은 감소하는 경향이고 특히 0˚와 15˚ 사이에서 급격한 변화율을 보인다. 2) 파단시 변화율은 인장방향에 대한 섬유방향이 45˚인 경우 최대치를 나타냈고 15˚~45˚ 범위에서 급격한 변화율을 보인다. 3)섬유의 방향이 동일할 경우 인장력을 많이 받은 시료일수록 최대절연강도 값은 낮아졌고 인장방향과 섬유방향의 교각이 증가할수록 최대절연강도 값을 나타내는 압축응력의 값은 낮은 점으로 이동하는 경향을 보였다. 4) 기계적 특성과 같이 섬유방향이 45˚인 경우의 시료가 가장 나쁜 전기적 절연강도 특성을 나타냈다.

GFRP 보강근과 콘크리트의 부착성능은 접착력, 부착력 및 지압력으로 발휘되며 보강근의 표면처리 방식이나 외피형상에 따라 발휘되는 부착저항력의 종류와 크기는 다르다. GFRP 부착 해석모델에 대한 선행연구를 살펴보면 철근의 부착 해석모델을 일부 수정하여 발전시키거나 수치해석을 통한 매개변수의 수가 많은 복잡한 해석식을 제안하였다. 전자의 경우에는 규격화된 마디형상을 갖는 철근과 달리 구성재료, 배합방법, 제조방법에 따라 다양한 외피형상을 가지는 GFRP 보강근의 특성을 포괄적으로 제안하는 데는 제약이 있으며 후자의 경우에는 수치해석으로 인한 수학적 관계식으로 GFRP 보강근의 부착거동과의 역학적인 관계를 고려하기에는 어려움이 있다. 따라서 이 연구에서는 GFRP 보강근의 콘크리트와의 외피형상에 따라 달라지는 부착메커니즘을 반영한 부착 해석모델을 제안하고자 하였다. 제안한 부착 해석모델에 대한 적합성 검증을 위하여 타 연구자가 수행한 실험값과 비교하였으며 기존의 부착 해석모델인 BPE 부착 해석모델과 CMR 부착 해석모델과의 비교연구도 수행하였다. 비교결과 이 연구에서 제안한 부착 해석모델이 실제 거동에 가장 근사하게 평가하였다.

The purpose of this paper is to assess the effect of surface characteristic of GFRP rebar on concrete-reinforcement bond behavior. For sample preparation, 10 GFRP rebar with two types of surface conditions were used to fabricate 15×15×15cm sized GFRP reinforced concrete. Then, pull-out test was carried out on each concrete samples until the maximum bond strength was achieved. From the test result, it was found that the maximum bond strength at the lattice type is 1.38 times higher than that for unidirectional surface.

The purpose of this study is to evaluate the tensile strength of GFRP and BFRP Rebar after exposure to environmental factors of deterioration (alkali, freezing -thawing) in order to present that as basic data for the application of FRP Rebar as concrete reinforcement. As a result, in the exposure of an alkali environment, the deterioration of fiber-resin was accelerated as the temperature increased, and it was found that there was an insignificant effect on freezing-thawing.

Numerical behavior of reinforced concrete(RC) column with GFRP seismic reinforcement was evaluated through the finite element analysis in this study. For the numerical analysis, a experimental test results was used to develop a nonlinear three dimensional finite element model of RC column with GFRP seismic reinforcement. The developed the nonlinear three dimensional finite element model of RC column with GFRP seismic reinforcement was well predicted the behavior, maximum strength and initial stiffness, of RC column with GFRP seismic reinforcement.

Numerical behavior of GFRP(Fiber Reinforced Polymer) infill panel in steel frame structure was evaluated through the finite element analysis in this study. In order to numerical analysis, a experimental test results was used to develop a three dimensional finite element model of steel frame specimen. Based on the developed three dimensional finite element model of steel frame specimen, the behavior of GFRP infill panel in the steel frame specimen was evaluated. From the numerical analysis results, strength of the steel frame specimen with GFRP infill panel was governed by GFRP infill panel. Also, diagonal compression behavior governed the GFRP infill panel in the steel frame specimen in the numerical analysis results.

Recently, researches on FRP bars have been carried out as a solution to improve the durability of reinforcing steel bars. In the study, an experimental program was conducted to evaluate the development performance of GFRP bars for SFRC beams. Specimens were failed by splitting fracture. The development performance by the center lap joint was larger than the development of end of beam. As the lap length increased, the development performance was increased but not proportional.

This study was conducted to investigate the confinement effect of circular specimens were confined to fiber composites (CF, GF, P·E·T, etc.). According to the test results, the cylinders strengthened with CFRP and GFRP showed improved strength and ductility when compared with the control cylinder. As the number of FRP sheets increased, load-carrying capacity increased, but ductility decreased. The specimen strengthened with PET indicated negligible strength improvement, but showed substantial ductility.

In this experimental study, the characteristic of damages on GFRP rebar exposed to high temperature only and immerged in alkaline solution after the exposure to high temperature was analyzed through microscopic image analysis. The found microcrack and pores in resin matrix were quantitatively compared if there was effect of pre-exposure to high temperature. The damages, such as microcrack and pores in resin matrix, by alkali exposure were mainly found in rebar surface. On the other hand, the pores caused by high temperatures were extensively found in a section and had greater width than those caused by the alkali exposure. In results of the quantitative comparison, the accumulated length and widths of microcrack and pores in resin matrix in pre-exposed GFRP rebar to high temperature were respectively 1.5 and 1.4 times of those in the GFRP rebar only immerged in alkali solution. Therefore, the deterioration of resin matrix by the alkali exposure could be accelerated due to the pre-exposure to high temperature.

This study was conducted to investigate the confinement effect of circular specimens were confined to fiber composites (CF, GF, P·E·T, etc.). According to the test results, the cylinders strengthened with CFRP and GFRP showed improved strength and ductility when compared with the control cylinder. As the number of FRP sheets increased, load-carrying capacity increased, but ductility decreased. The specimen strengthened with PET indicated negligible strength improvement, but showed substantial ductility.

시멘트 생산 과정에서 생성되는 이산화탄소 배출량을 감소시키기 위하여 시멘트를 대체할 수 있는 건축 재료 개발에 많은 연구가 진행되어왔다. 시멘트 대체재로 사용될 수 있는 활성 황토는 850°C에서 소성 과정을 거쳐 제작된다. Poly-Vinyl Alcohol(PVA) 섬유와 GFRP 보강근은 활성 황토 콘크리트의 균열 문제를 해결하기 위하여 사용된다. 본 논문은 PVA 섬유 보강 활성 황토 콘크리트에 대하여 인발 하중에 따른 GFRP 보강근의 부착 성능을 평가하기 위한 실험 연구를 나타내고 있다. 실험 결과, 황토가 치환된 PVA 보강 및 무보강 실험체들의 평균 부착 응력 계수가 2.27~2.48로 나타났으며, 부착 응력 계수가 PVA 섬유 보강 유무 및 황토 치환율에 크게 영향을 받지 않는 것으로 나타났다. 그리고 부착 길이가 길어질수록 부착 강도는 저하되었다.

This study was conducted to develop a bended steel-hybrid GFRP (Glass Fiber Reinforced Polymer) bar. The steel-hybrid GFRP bar was to develop for replacing steel rebar for RC structures which were built in the corrosive environment. To be used for RC structures, a bended type of steel-hybrid GFRP bar is required. This study explains the results of current status of the project.

Based on the study of the Rule of Mixture for FRP (Fiber Reinforced Polymer), it was found that the tensile strength of FRP rebars (reinforcing bars) with circular cross-sections could be estimated with proper reduction coefficients. In this study, a reduction coefficient for FRP rebars with a diameter of 16 mm was proposed.

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.

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.

The object of this study is to investigate the confined effects of specimens using GFRP(glass fiber reinforced polymer) sheet and PET(polyethylene terephthalate) sheet. Since GFRP and PET sheet have a grate deformation capacity, the brittle failure of concrete can be avoid. A total of specimens is sixteen and major variables are the type of strengthen material and strengthening layer. As a result of test, specimens reinforced with a glass fiber sheet compare to the standard specimen have a significant increase both strength and ductility. Ductile of the specimens reinforced with PET is superior to it of the GFRP regardless of strengthening layer. However, in the strength effect aspect is not great compare to the ductile. Resultingly, it is judged that the reinforced method with PET is available to apply field application.

This study is to understand the structural behavior of flexural member according to the splice length of specimens reinforced by GFRP reinforcing bar. As compared with reinforcement, GFRP reinforcing bar has superior material properties such as non-corrosiveness, light weight, non-conduction, etc. However, GFRP reinforcing bar is difficult to use instead of reinforcement owing to brittle fracture when it failed. Therefore, GFRP reinforcing bar mixed with deformed reinforcing bar were used. A total of 5 specimen was produced and tested and the test main variables are the diameter of tension steel, lap splice length of GFRP reinforcing bar which are for investigating the reinforcement effects. The diameter of tension steel set as D10, and D13 and the lap splice length of GFRP reinforcing bar set as 30db, 45db and, 60db. The results of the experimental test, the specimen with GFRP reinforcing bar proved more reinforcement effect than the one without GFRP tie bar. At the same time, the specimen with tension steel of D13 increased an overall strength more than the one with tension steel of D10. The longer lap splice length showed increase the strength.

FRP(Fiber Reinforced Polymer) reinforced lightweight concrete structures can offer corrosion resistance and weight reduction effect simultaneously, so practical use of the structures may be expected afterwards. During that time, a lot of studies for bond behaviors of FRP bar in normal concrete were conducted, but studies for bond behavior of the FRP bar in lightweight concrete are very limited to date. So, bond characteristic between lightweight concrete and helically deformed GFRP bar was investigated in the former study by the authors. In this study, re-consideration of the bond capacity were performed by using results of the former study, results from additional experiment considering variation of the concrete compressive strength, and results from literature survey.

the primary objective of this research is to reduce the damage of critical frame structures such as hospitals and schools during and after an earthquake. this study develop the infill panel to allow smaller shear deformation with sliding of the specific element in the panel. As a result, the side sway was significantly reduced in the structure with infill panel, in comparison to the steel frame structure without infill panel during the experimental test

This study presents the Finite Element(FE) analysis using ABAQUS with respect to new type of modular bridges. In addition, this research was carried out for safety analysis in term of stresses and deformation of the modular bredge incorporated with GFRP to the steel plate during lifting.