편심축하중을 받는 강섬유보강 콘크리트기둥의 내하거동

박홍용,안영진 명지대학교 산업기술연구소 2001 産業技術硏究所論文集 Vol.20 No.-

Steel fiber reinforced concrete is a cement-based material reinforced with short steel fibers. When steel fibers are added to a concrete mix, they are randomly distributed and act as crack arrestors. Debonding and pulling out of fibers require more energy, giving a substantial increase in toughness and resistance to cyclic and dynamic loads. An experimental study on the Load-Carrying Behavior of Steel Fiber Reinforced Concrete Columns under eccentric compression are presented. Forty-two high-strength(300 kgf/㎠) columns were tested; the variables were specific eccentricity, fiber contents, and longitudinal reinforcement ratio. The column size was 250×160 mm in cross section with an effective length of 1,150 mm. Specific eccentricity was varied in the range from 1/6 to 1/2 times the column depth. This paper is to provides a framework for basic understanding fo the Load - Carrying Behavior of steel fiber concrete columns.

외부 프리스트레싱으로 보강한 철근 콘크리트 T-형보의 STM 해석

박홍용,박영준 명지대학교 공학기술연구소 1994 공학기술연구소 논문집 Vol.9 No.-

Most of the concrete structures which were built 20's years ago and have been used till now have become obsolete. Particularly, bridges designed as 2nd or 3rd level are required repairing and reinforcing or demolition because of rapidly increasing traffic and vehicles heavier. Recently, the advanced countries including France have made a satisfactory success in constructing the long-span bridges and strengthening the flexural strength of the existing structures by the external prestressing. This paper carried out on externally prestressed beam by the STM. More exactly, Variation of the load carrying capacity depended on a deviator location was studied by the STM analysis under the ultimate load condition and by the FEM analysis under the service load condition. The test model was 3rd level bridge which had been made of R.C T-sections 30's years ago. As a result of the STM analysis derived a simple fomula to get the value of the required external prestressing force and could be confined the extend of that. On the contrary, the FEM analysis presented the mechanical behavior that does the better, when the tendon is prestressed along the beam with the large eccentricity and with the bigger horizontal angle near the supporting point. In view of theses facts, before designing the concrete structures with external prestressing. It is neccessary to ivestigate the influences of the deviators under the both ultimate load condition and service load condition.

철근콘크리트 T-형보 교량의 횡분배 거동에 관한 연구

朴弘用 명지대학교 1985 明大論文集 Vol.16 No.-

The load distribution response of simply-supported reinforced concrete T-beam bridge has been examined. To obtain the response, six R.C.-T-beam bridges which had been tested by MOC, 1972, have been selected. The comparison between measured values and calculated values are made in this paper. Calculated values are from the method of orthotropic plate theory by Guyou-Massonet and the method of grillage theory by leonhardt and Homberg. It is the purpose of this paper to present the reference data in field testing of R.C.T-beam bridge with or without cross beams within the elastic behavior range.

PC桁橋의 載荷試驗과 PC桁의 橫分配 擧動에 關한 硏究

朴弘用,朴英錫 명지대학교 1985 明大論文集 Vol.16 No.-

The induced static response of a simply-supported prestressed concrete girder bridge has been examined. The deflections and strains were induced by calibrated test vehicles. The experimental results, deflections and strains have been compared to results from analytical technique using grillage-theory without torsional rigidity of PC girder. The comparisons show some discrepancies between test and theory. In this paper, the reason has been examined and the method of field testing on bridge has been proposed. It is therefore the purpose of this paper to present the reference data in field-testing of PC girder bridge with several cross beams within the elastic behavior range.

콘크리트 부재의 균열 형성과 균열 폭 산정

박홍용 명지대학교 공학기술연구소 1988 공학기술연구소 논문집 Vol.3 No.-

Presented is a study on the formulation of crack width and crack spacing formula in the reinforced - and prestressed concrete flexural members. The derivation of crack width and spacing is based on the classical crack theory developed mainly in Europe. An experiment for the partially prestressed concrete slabs was conducted to compare with some crack widths prediction formulae proposed by European researchers. The comparision shows that some European formulae have a good agreement with the test data, but that Gergely's and IBS's make some differences.

AFRP로 보강된 철근콘크리트 슬래브의 휨 거동에 관한 실험 연구

홍규창,박홍용 明知大學校 産業技術硏究所 2000 産業技術硏究所論文集 Vol.19 No.-

The reinforced concrete slabs with epoxy-bonded AFRP sheets were experimentally investigated. Experimental data on strength, stiffness, steel strain, deflection and mode of failure of strengthened slabs were obtained, and comparisons between the different flexural reinforcing schemes and reinforced concrete slabs without AFRP sheets were made. It can be concluded that flexural strengthened with AFRP has increased, and that ductile behavior of strengthened slabs has decreased.

鐵筋콘크리트 슬래브의 有限要素解析

朴弘用,이상희 명지대학교 공학기술연구소 1986 공학기술연구소 논문집 Vol.1 No.-

The objects of this study are to develop constitutive relations for reinforced concrete which account for the effects of cracking and to apply these non-linear constitutive relations to a finite element analysis of reinforced concrete slabs. To represent the behavior after cracking, slab element is treated as a bimodular material for which the modulus of elasticity in tension may be different from that in compression. Reinforced concrete slabs have generally been analyzed on the basis of classical small displacement plate bending theory assuming the material to be linear elastic, homogeneous and isotropic, thereby neglecting the effects of cracking. But in this study, classical small displacement plate theory is modified for a non-homogeneous, orthotropic material. In this study, as method of numerical analysis finite element method is selected. And this method is used to obtain an approximate solution for the transverse displacement. Iterative solution method for the effect of cracking is used to analyze the behavior of reinforced concrete slabs after cracking. The initial stiffness method and tangent stiffness method are used to apply the stepped load on slab before or after cracking. In this study, transverse shear effect as well as time dependent effects, bond slip between the reinforced and concrete, tension stiffening effect and thermal effect are not considered. Only non-linear behavior after cracking is considered. Results obtained by numerical analysis are compared with the those of experiments and other studies. As a result, the more the number of elements increased, the more analysis value approached experimental value. And if layers are elaborately separated to thickness of slab, cracking depth will be approximately suggested.

한계상태설계법에 의한 부분프리스트레스트 콘크리트 교량의 자동차 설계 프로그래밍

박인교,박홍용 明知大學校 産業技術硏究所 2000 産業技術硏究所論文集 Vol.19 No.-

Partially prestressed concrete members are concrete members reinforced with a combination of prestressed and non-prestressed reinforcement, and also can offer advantages of reinforced concrete. The objective of this study is to develop a design program using Visual Basic language according to the limit state design method which controls crack and check fatigue effectively for partially prestressed concrete members.

강섬유보강 철근콘크리트 일방향 슬래브의 휨거동에 관한 실험 연구

박홍용,문정규 명지대학교 산업기술연구소 2001 産業技術硏究所論文集 Vol.20 No.-

Concrete is strong in compression but vulnerable in tension. As a result, crack develops when static loading applied, and failure abruptly appeared when dynamic loading condition. This vulnerability can be improved through the addition of steel fibers in the concrete mix. This experimental test was investigated on the influence of steel fiber reinforcement on flexural behavior characteristics of slabs with various steel fiber contents(Vf) and aspect ratio(ℓ/Φ). Deflection, crack width, and strain of steel bar were measured at every load step. In the results of this experimental test, the addition of steel fibers to conventionally reinforced concrete slab increased the ultimate load, reduced the crack width, the average crack spacing, and deflection.

이종 섬유 혼입비에 따른 섬유보강 콘크리트의 휨 인성 및 휨 인장강도에 관한 연구

박홍용,류종현,조용범,Park, Hong-Yong,Ryu, Jong-Hyun,Jo, Yong-Bum 한국터널지하공간학회 2010 한국터널지하공간학회논문집 Vol.12 No.1

최근 새로운 형태의 폴리올레핀 섬유에 대하여 성능향상 개발이 이루어지고 있으며, 기존 섬유와 혼입하여 사용하거나 폴리올레핀 섬유만을 사용한 콘크리트 특성에 대하여 연구와 검증이 필요하다. 본 연구의 목적은 강섬유와 폴리올레핀 섬유를 사용한 콘크리트의 휨 인성 및 휨 인장강도에 대한 성능을 확인하기 위하여 324개의 보 시편을 제작하고, KS F2566과 ASTM C 1399-02규격에서 제시한 4점 휨 실험을 수행하여 휨 인성지수, 등가 휨 인장강도, 평균잔류강도를 분석하였다. 실험결과, 섬유 혼입률, 섬유 형상비에 대한 휨 인성 및 인장강도에 대한 효과가 확인되었으며, 강섬유와 폴리올레핀의 최적의 혼입비율을 제시하였다. Recently, a new type of polyolefin fiber having a good mechanical properties is being developed, and it is necessary to examine a possibility for the new fiber together to be used as a reinforcing fiber with other types of fiber or by itself. The objective of this study is to find flexural toughness and tensile strength of concrete reinforced with steel and polyolefin fibers. Four point beam tests were performed with 324 specimens following two standard tests methods: KS F 2566 and ASTM C 1399-02. From the test results, the effects of volume fraction of fibers, and aspect ratio of steel fiber on the toughness and tensile strength were investigated, and the optimal ratio of steel fiber to polyolefin fiber was suggested.