휨부재의 인장철근비 변화에 따른 섬유보강에폭시 판넬의 보강효과평가

강성후,박선준,송영국 東新大學校 工業技術硏究所 2003 工業技術硏究 Vol.9 No.-

FREP is a stiffener that is increasingly used in construction fields today. Concerning it, however, the mechanical characteristics of structures reinforced with it, reinforcement design methods, etc. have not been systematically established yet. The present study evaluated the mechanical characteristics of FREP such as fracture behavior, bending stress enhancement, etc. through a bending test using as variables steel ratio of RC beams reinforced with FREP and the thickness of FREP reinforcement. The RC Beams used in the test showed two types of fraction, which were bending tension fraction and edge stripping fracture, and when the ratio of steel ratio (ρ) to FREP ratio (ρ_(F)) is larger than 1.8, it showed edge stripping fracture. Under same reinforcement condition, if steel ratio is relatively low, reinforcement effect appeared to be high. In addition, if reinforcement thickness increases, the flexural rigidity rises and, as a result, the maximum load also increases, but an excessive increase of reinforcement thickness makes stress concentrate on the reinforced end and cause unexpected brittle fracture (edge stripping fracture) even at a light load.

접착 보강공법에 따른 R.C. T형교의 휨 내하력 증가에 관한 연구

강성후,정홍곤 東新大學校 工業技術硏究所 2000 工業技術硏究 Vol.6 No.-

While the F.R.E.P.(Fiber Reinforced Epoxy Panel) adhesion construction method and the Carbon Fiber Sheet adhesion construction method, which have been developed to solve the problems in existing materials for repair and reinforcement and in construction, are similar to each other in the principle of reinforcement, the extent of application and the construction method and have been employed more frequently in construction fields of civil engineering, the verification of the effects of repair and reinforcement has been insufficient compared to other construction methods. Therefore, in this Study, the data of a R.C. T-Girder bridge before and after reinforcement is compared and analyzed especially in terms of the load carrying capacity, and the results will be used as basic data for repair and reinforcement of RC bridges that are expected to adopt the F.R.E.P. adhesion construction method and the Carbon Fiber Sheet adhesion construction method.

R.C. 라멘교의 윤하중분포폭 산정식 제안

강성후,박선준,김규형 東新大學校 工業技術硏究所 2001 工業技術硏究 Vol.7 No.-

The wheel load distribution width is used to consider transverse distribution effect when bridge is designed. But, the wheel load distribution width of R.C. slab which has a structural difference is used to design the R.C. rahmen bridge. This study aims to propose equations of wheel load distribution width for R.C. rahmen bridge. MIDAS GENw program, finite element analysis program, was utilized to calculate the wheel load distribution width. Result of finite element analysis that use MIDAS GENw was analyzed by SPSS that is the statistical analysis program. The proposed equations in this study compared with domestic bridge design code and AASHTO LRFD code. These equations can be used usefully when R.C. rahmen bridge design.

강박스 거더교 콘크리트 바닥판에 발생하는 크리이프와 건조수축에 관한 연구

강성후,박선준,김현일 東新大學校 工業技術硏究所 2002 工業技術硏究 Vol.8 No.-

It studies the non-structural crack factors that are produced in Steel Box Girder Bridge concrete floor plate using analytical method. It mainly studies humidity and design standard of concrete strength. It used MIDAS CIVIL Ver 5.4.0, a general structure analysis program that applies drying shrinkage rate of domestic road bridge design standard and standard value of creep coefficient, CEF-FIP standard equation and ACI standard equation from the aspect of creep, drying shrinkage and hydration heat to see the effect of the two factors on concrete crack and found the following result. The analytical results of this study showed that the initial stress, which was obtained by ACI standard, exceeds the allowable tensile stress between 5 to 18 days. This result means that even if a bridge is designed and constructed according to design standard, the bridge can have cracks due to various variables such as drying shrinkage, hydration heat and creep that produce stress in slab.

팽창 콘크리트의 재료특성에 관한 연구

姜聲厚 東新大學校 工業技術硏究所 1997 工業技術硏究 Vol.3 No.-

This study aimed at investigating the material Properties of expansive concrete. In order to determine material Properties of expansive concrete (Compressive strength : δ_(c), Split tensile strength : δ_(sp), Modules of Elasticity : E_(c)) and Fracture energy(G_(F)), Six expansive concrete mixtures were studied ; for instance when varying the expansive cement ratios and admixtures(silica fume, water reducer), slump value should be kept constant. The fracture energy(G_(F)) was obtained from the three-point bending test on the 70cm beam in length recommended by RILEM 50-FMC Committee. 30 specimens in test are single edge notched three point bend beams that are the opening mode recommended by RILEM 50-FMC Committee.

동적하중을 받는 콘크리트보의 파괴에너지 해석

姜聲厚,柳井善,孫官哲 東新大學校 工業技術硏究所 1994 工業技術硏究 Vol.1 No.-

In this study, after concrete cylinders were made on the condition of varying water-to-cement ratio, and cured 80 days compressive strength and splitting tensile strength were performed and modulus of elasticity is obtained. The fracture energy was obtained by acting three point bending on the 80cm in length. This test involved static loading test and dynamic loading test. In this work, the new interrelation of the material constants was obtained clearly and the property of the mixture was inspected, including the relation between the fracture energy and all kind of the material constants.

유한요소법을 이용한 고성능 콘크리트의 파괴거동

강성후,박선준,박상균 東新大學校 1999 論文集 Vol.11 No.-

As structures made of concrete are getting more high-rise and large-sized, it is necessary to fortify the concrete, the basic material of construction. Concrete's degree of strength is getting more improved due to these basic needs and researches on the subject are actively under way. This study is to predict mechanical behavior and fracture behaviors of high performance concrete. For that purpose, The writer fixed water-cementitious ratio at 33% and used finite element method based upon results of three-point bending tests by having six different types of test pieces with varying mixture ratio of silica fume, water reducer, and superplasticizer. With the finite element method, The writer compared the result of three-point bending test with fracture parameters which was acquired from nonlinear fracture analysis, from which mechanical behavior and fracture behavior of high performance concrete were predicted and usefulness of applied programs was verified.

수치해석을 이용한 콘크리트의 균열저항곡선 해석

강성후,김민성 東新大學校 工業技術硏究所 1999 工業技術硏究 Vol.5 No.-

Predictions of crack process condition of concrete and fracture parameter have been investigated using the finite element method since concrete fracture mechanics has been introduced. This study is to investigate on the prediction of fracture parameters measured from concrete by applying numerical interpretations based on fracture interpretations of crack process. As the stress from crack tip reached maximum value the crack initiated, and as an unstable crack critical load( P_(IC)) the specimen started to spread and finally to fail. Fracture characteristics values were calculated including effective crack length(a_(e)) and R-curve start point of unstable crack(a_(IC)), which occur due to the working load in nonlinear minute crack of the crack tip.

3경간 연속 중로식 강아치교의 내풍안정성을 고려한 라이즈 비 특성

강성후,박선준,최명기 東新大學校 工業技術硏究所 2004 工業技術硏究 Vol.10 No.-

The most important element is a rise ratio when regarding beauty and economics of arch bridges. Only the effect of dead load has been considered to decide the rise ratio. In this study, when going over the rise ratio of arch bridges, examined the problems, that the determination of the rise ratio by the dead load has, by adding the factor of a determination of optimum rise ratio, which is not only the effect of the dead load that has been currently considered but also the problem with respect to wind resistant dynamic stability that is now taken seriously. Synthetically, when deciding rise ratio that is investigated in basic step of design, it is not necessary to consider the evaluation wind resistant dynamic stability. Therefore the result of this research can be summarized as followes ; If it is identify oneself with rise ratio that the divided ratio due to the tie girder of the 3 continuous spans half-through steel arch bridges cannot cause a big effect in stability the wind resistant dynamic stability. If it is identify oneself with the relative stiffness ratio and girder depth ratio of the 3 continuous spans half-through steel arch bridges that the rise ratio proposes that it uses 0.10~0.30, divided ratio due to tie girder proposes that it uses 1.0~2.5 because of the wind resistant dynamic stability and the stress of the hanger. The rise ratio proposes that it uses 0.16~0.18 is given by the Japanese bridge construction association to obtained in investigation equation between an arch span length and the rise, using 0.1~0.2 at the basic design phase and the divided ratio which using 1.5 due to tie girder generally has been employed to main results and very well agrees with a research accomplishment results.

파괴에너지를 고려한 콘크리트 배합설계 프로그램

강성후,박선준,노호현 東新大學校 工業技術硏究所 2001 工業技術硏究 Vol.7 No.-

In the concrete structure, there are many possibilities existing cracks that are produced and developed from the infinitesimal crack in the member, fatigue or corrosion being not existing in the early period. Also, it is not enough to explain the fracutre behavior using the strength theory. Because the concrete reach to the shear due to main cracking after developing infinitesimal crack when it is received the tension stress. But it is hard to solve the structural problem of concrete, because current analysis and design methods of structure are based on the strength of concrete. Hence the subject of this thesis is programming the design of automatic mix design program to do automatic concrete mix design and to consider fracutre energy depending on mix condition.