• 한국강구조학회 논문집
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• 제17권4호통권77호
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• pp.481-490
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• 2005

본 논문은 중력하중의 지배를 받는 CFT기둥-RC 무량판 접합부의 실물대 실험결과를 요약한 것이다. CFT구조는 여러 가지 구조 및 시공상의 장점으로 인하여 국내 건설 현장에서 상대적으로 짧은 시간에 폭넓게 수용되고 있다. 주차장 용도로 주로 사용되는 지하층은 철근콘크리트 무량판으로 시공하여 경제성을 도모하는 것이 국내에서 일반적으로 요구되는 시공관행이다. 그러나 CFT기둥-RC 무량판 접합부의 효율적인 디테일은 아직 국내 외적으로 제시된 바가 없어서 이 분야의 연구가 매우 필요한 실정이다. 현장 시공시 경제성을 극대화할 수 있는 몇 가지 전략을 기초로 해서, 여러 가지 접합 상세를 제안하였고 실험을 통하여 검증하였다. 실험결과 본 연구에서 제시된 CFT기둥-RC 무량판 접합 상세의 펀칭강도 및 강성이 RC 무량판 접합부와 동등하거나 이를 상회하는 것을 확인할 수 있었다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2005년도 학술발표회 논문집
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• pp.203-210
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• 2005

This paper summarizes full-scale test results on CFT column to flat plate connections subjected to gravity loading. CFT construction has gained wide acceptance in a relatively short time in domestic building practice due to its various structural and construction advantages. Constructing the floor as flat plate is often regarded as being essential for both cost savings and rapid construction. However, efficient details for CFT column to flat plate connections have not been proposed yet, and their development is urgently needed. Based on some strategies that include maximizing economical field construction, several connecting schemes were proposed and tested in this study. Test results showed the proposed connection details can exhibit strength and stiffness comparable to or greater than those of R/C flat plate counterpart.

• 한국강구조학회 논문집
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• 제20권1호
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• pp.205-213
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• 2008

SM570TMC 강재를 합성부재로 사용할 경우, KBC2005 0709에 따라 ${415N/mm^{2}}$를 초과하지 못한다. 이는 일반 강구조의 경우의항복강도 ${440N/mm^{2}}$에 미치지 못한다. 따라서 본 연구는 순수강재 (원형강관, 각형강관) 단주 압축실험과 충전형 합성부재 단주, 장주 압축실험을 통하여 SM570TMC강을 충전형 합성기둥으로 사용할 때, 항복강도를 저감시키지 않고 일반 강구조의 공칭강도를 그대로 사용할 수 있는지를 정량적으로 평가하는데 그 목적이 있다.

• 한국지진공학회논문집
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• 제12권1호
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• pp.21-28
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• 2008

CFT(Concrete Filled Steel Tube)기둥은 부재의 합성효과와 경제적인 측면 때문에 최근 고층건물 시공 시 널리 쓰이고 있다. 그러나 기존의 연구문헌을 살펴보면 CFT 기둥은 강관의 항복이후 강관의 일정지점에 국부좌굴이 생기는 단점을 지니고 있다. 이러한 문제점을 해결하기 위하여 예상 국부좌굴부위를 탄소섬유쉬트로 보강하여 국부좌굴을 방지하거나 지연시키는 TR-CFT (Transversely Reinforced Concrete Filled Steel Tube) 기둥에 관한 연구가 진행되고 있다. 본 연구에서는 고강도 콘크리트를 사용한 TR-CFT기둥의 실험을 수행하였으며 휨내력에 대한 해석을 수행한 결과 실험값과 해석값이 잘 일치하였다. 또한 기존의 ACI 318 설계법은 강관내부에서 발생하는 콘크리트에 대한 구속효과를 고려하지 않아 저평가가 되어있음을 알 수 있었다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2008년도 춘계 학술논문 발표대회
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• pp.31-34
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• 2008

Construction of buildings downtown is increasing as much as ever with a strong demand. A Top-Down Method is suitable for its advantage in minimizing its disturbance to the neighborhood. In general, the Pre-founded Column, one of the most important aspects of the Top-Down Method, has been made with an H-Shape Steel Column. However, due to its structural and economical benefits, the usage of CFT(Concrete Filled Tube) columns in the place of Pre-founded Columns is increasing. To promote their applications, we analyze the merits of CFT columns by comparing them with I-Shape columns and propose further research.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2008년도 춘계 학술논문 발표대회
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• pp.193-197
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• 2008

Recently, it increases in use of CFT(Concrete filled steel tube, below CFT) that is an excellent internal force and deformation capacity because material and method are required to be diversification and High-Performance according to increase the super-high structure. And it is proposed to use high-strength Concrete Filled steel Tube Column. But it is difficult quantitative evaluation about fire-resist performance of CFT because steel tube bind concrete. Also, the case of high strength CFT is feared that spalling occur inside. Therefore, this study made CFT specimen that determine the factor(which is strength of concrete) and then CFT column was exposed to heating controlled as closely as possible the ISO-834 standard fire curve. Also, it tried to analyze internal temperature through nonlinear transient heat flow analysis.

• 한국강구조학회 논문집
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• 제14권1호
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• pp.121-130
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• 2002

This paper presents the tensile behavior of a Concrete-Filled Square Steel Tubular (CFT) column to H-beam welded connections. These connections were externally reinforced with T-shaped stiffeners at the junction of CFT column and beam. The tensile loading tests of eighteen tee-joint connections and finite element analysis using ANSYS were carried out. The main parameters of tests are as follows: 1) the thickness of Square Steel Tubular Column : 6 mm, 9 mm, 2) the strength ratios of tensile strength of horizontal stiffeners to tensile strength of beam flange : 70 %, 100 %, 150 %, 3) the strength ratios of shear strength of vertical stiffeners to tensile strength of beam flange : 80 %, 115 %, 160 %. The results of the tests demonstrate that overall behavior and failure modes of all the specimens are governed mainly by the horizontal stiffeners rather than the vertical stiffeners, and the vertical stiffener played only a role in transferring load introduced from beam to column.

• 한국강구조학회 논문집
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• 제24권1호
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• pp.81-89
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• 2012

콘크리트 충전강관 기둥은 내부의 콘크리트에 의해 축열효과로 인해 철골기둥에 비해 내화성능이 우수하며, 기둥 단면 내 철근 및 강관을 보강하여 구조적내력 및 내화성능 향상연구가 이루어져 오고 있다. 실제로 보강된 CFT기둥은 고축력을 요구하는 기둥부재로 사용 빈도 수가 증가되고 있는 추세이다. 이러한 상황에서 CFT기둥을 사용한 건축물에 화재가 발생하여 손상을 입게 되었을 경우 성능 저하정도를 정밀하게 측정할 수 있는 기법이 필요하다. 본 연구에서는 화재 발생시 CFT기둥에 대한 내부 온도 분포를 평가 하고, 단면내부의 온도분포에 따라 내부 충전콘크리트와 보강재의 내력 저하 정도를 파악하여 CFT기둥의 전체적인 잔존강도를 평가하고자 한다.

• 한국건축시공학회지
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• 제4권1호
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• pp.127-132
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• 2004

CFT(Concrete Filled Steel Tube) is a structure of circular or squared of steel column filled with concrete. The steel tube holds the concrete inside and that makes this structure to perform superior features on stiffness, proof stress, transformation, fire resistance and construction itself. In this study, by over the 800kgf/$\textrm{cm}^2$ of high strength concrete for CFT column, research has been done on the basic property of matter such as fluidity, resistance on segregation, compressive strength, setting icons of the concrete filled in the steel tube under conditions of standard weather. Physical properties of concrete for CFT that Concrete with silica fume, fly ash of air entraining and high-range water reducing agent, that used to CFT column research purpose to find the most ideal composition, which is achieved by the investigation in the concrete's property of matter like ability of Slump, Slump Flow, Air content, Bleeding, and Settlement. For this study, experiments which are bused on obtained the result through physical test are practiced, with all of the experiment, specimens only for control are produced in each method of curing and analyzed to relations with core strength in mock-up test. In mock-up test, the research is studied compactability of concrete filled in tube and degree of hydration hysteresis, as a basic reference for applying to field of CFT column which is used over 800kgf/$\textrm{cm}^2$ high strength concrete.

• Steel and Composite Structures
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• 제10권2호
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• pp.187-205
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• 2010

The existing CFT columns present the deterioration in confining effect after the yield of steel tube, local buckling and the deterioration in load capacity. If lateral load such as earthquake load is applied to CFT columns, strong shearing force and moment are generated at the lower part of the columns and local buckling appears at the column. In this study, axial compression test and beam-column test were conducted for existing CFT square column specimens and those reinforced with carbon fiber sheets (CFS). The variables for axial compression test were width-thickness ratio and the number of CFS layers and those for beamcolumn test were concrete strength and the number of CFS layers. The results of the compression test showed that local buckling was delayed and maximum load capacity improved slightly as the number of layers increased. The specimens' ductility capacity improved due to the additional confinement by carbon fiber sheets which delayed local buckling. In the beam-column test, maximum load capacity improved slightly as the number of CFS layers increased. However, ductility capacity improved greatly as the increased number of CFS layers delayed the local buckling at the lower part of the columns. It was observed that the CFT structure reinforced with carbon fiber sheets controlled the local buckling at columns and thus improved seismic performance. Consequently, it was deduced that the confinement of CFT columns by carbon fiber sheets suggested in this study would be widely used for reinforcing CFT columns.