• Magazine of the Korea Concrete Institute
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• v.14 no.6
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• pp.88-95
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• 2002

최근 국내에 60층을 초과하는 초고층 구조물들이 많이 건설되고 있으며, 콘크리트 품질의 향상 특히 콘크리트의 고강도화에 힘입어 이를 이용한 철근 콘크리트 고층 구조물들이 증가하고 있다. 이에 따라 이들 초고층, 초대형 구조물을 지지할 수 있는 고축력, 고연성의 기둥에 대한 설계 및 시공이 요구되고 있으며, 이에 가장 적합한 구조요소라 할 수 있는 콘크리트 충전 강관기둥(Concrete Filled Steel Tube Columns : CFT Columns)의 설계 및 시공에 관심이 높아지고 있다. 이러한 콘크리트 충전 강관기둥은 콘크리트가 강관에 의해 둘러싸여지기 때문에 축하중 저항 능력이 증가되는 장점과 동일한 단면으로 H형강을 사용한 순수 철골조 H형강 기둥의 강축(strong axis)과 약축(weak axis) 문제해결과 동시에 강성 (stiffness)을 증가시킬 수 있으며, 내화 성능이 향상되고 거푸집 대체 재료로 사용되는 등 여러 가지 장점을 지니고 있다. 한편 충전 강관기둥에 작용하는 축하중은 대부분 콘크리트가 부담하게 되는데 이러한 충전강관 기둥의 장점을 극대화하기 위해서는 보통강도 콘크리트보다는 압축강도 및 탄성계수가 큰 고강도 콘크리트의 사용은 불가피하게 된다.(중략)

• Journal of Korean Association for Spatial Structures
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• v.8 no.5
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• pp.59-65
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• 2008

Recently, to improve the load carrying capacity of column structures such as bridge piers, application to concrete-filled steel tube(CFT) type columns are increased more and more. To design the concrete-filled steel tube(CFT) columns in accuracy, influence of material and geometry properties and aspect ratio on ultimate strength of the concrete-filled steel tube column is investigated by experimental researches. In this investigation, the ultimate strength distribution of the concrete-filled steel tube column in accordance with diameter-thickness ratio(D/t) and steel-concrete area ratio(As/Ac) are clarified by the compressive tests. Futhermore, parametric experimental investigation on concrete target strength is performed. It was known from experimental observation that ultimate strength of concrete-filled steel tube column under axial compressive loading more depends on section properties of steel tube rather than concrete strength.

• Journal of Korean Society of Steel Construction
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• v.10 no.2 s.35
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• pp.177-186
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• 1998

The concrete filled steel tubular column have to superior in compressive load carrying capacity, compared with same section typed hollow steel tube column, and have many excellent structural properties, such as stiffness improvement by filled concrete, improvement of ductility by reinforced effect of local buckling, and the like. However, it has not clear the effect of interaction between steel tube and filled concrete, stress portion ratio and fracture mechanism of concrete. This study investigated to structural properties for high strength concrete filled steel tube column by loading conditions through a series of experiments. Especially, this study investigated the properties of structural behaviors for concrete filled steel tube column stress ratio by loading conditions and failure mechanism of filled concrete.

• Journal of Korean Society of Steel Construction
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• v.11 no.3 s.40
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• pp.311-318
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• 1999

Concrete filled tubular(CFT) members have many structural and constructional advantages. The prefabrication of CFT members can be thought an idea for the good qualify control of concrete. The objective of this study is to suggest the construction method of prefab CFT beam-columns. Tests are performed to understand their structural behaviors. The opening space between prefab CFT members and the size of tubular members are the parameters of this study. The results of this study will be based on the suggestion of prefab CFT.

• Journal of Korean Association for Spatial Structures
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• v.7 no.6
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• pp.69-74
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• 2007

Recently, to improve performance and strength of circular steel columns, application of concrete-filled steel tube(CFT) type are gradually increased. To accurately predict the plastic design of concrete-filled steel tube columns, a plasticity model is required which can be describe large deformation behavior of concretes and steels. In this study, elastic-plastic large deformation analysis is developed by using the plasticity model of structural steels, and accurate and validity of the developed program is verified by comparing between the experiment and the analysis for concrete-filled steel tube column. In concrete-filled steel tube columns, influence of initial deflection on ultimate strength behavior is investigated by using developed program.

• Journal of Korean Society of Steel Construction
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• v.13 no.1
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• pp.71-79
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• 2001

The concrete filled tubular(CFT) columns have many excellent structural properites. such as high compressive strength high ductility and high absorption capacity However the confinement effect and limiting width-thickness ratio of CFT column have not yet been clarified. Therefore. this paper aims to clarify the confinement effect of steel tubes and strength of concrete filled steel tubular columns. And this paper presents results of a probabilistic analysis based on statistical data for strength of concrete filled steel tubular columns which has been tested in Korea for recent 10 years(1991.1~2000.6).

• Journal of Korean Society of Steel Construction
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• v.11 no.1 s.38
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• pp.89-98
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• 1999

The objective of this paper is to investigate the structural behavior of concrete filled steel tubular columns subjected to eccentric load. With experiment and analytical study, the buckling behavior of columns is investigated and compared with each other to the view of main parameters. Appling foreign standards in the experimental results, we suggested new strength formula of concrete-filled steel tubular columns. The parameters are slenderness, eccentric ratio, and concrete filled or not. The experiment are carried out by simple loading.

• Journal of Korean Association for Spatial Structures
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• v.6 no.1 s.19
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• pp.55-63
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• 2006

Concrete-filled steel columns consist of circular, square or rectangular hollow sections filled concrete. Much research has studied for the behavior of concrete-filled steel structures. The advantages from structural point of view are the triaxial confinement of the concrete within the section, and the fire resistance of the column which largely depends on the residual capacity of the concrete core. The axial capacity of a concrete-filled rectangular or circular section is enhanced by the confining effect of the steel section on the concrete which depends in the magnitude on the shape of the section and the length of the column. Buckling tends to reduce the benefit of confinement on the squash load as the column slenderness increases. In circular sections it is possible to develop the cylinder strength of the concrete. When compare with reinforced concrete columns, the concrete-filled composite column possesses much better strength and ductility in shear and generally in flexure also. Many researches are being conducted about concrete filled steel column to get these advantages in building design. In this paper it is provided to the basic experimental study of compression behavior of the circular and rectangular tubular steel pipe filled with concrete.

• Journal of Korean Society of Steel Construction
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• v.17 no.5 s.78
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• pp.605-615
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• 2005

Experimental and analytical work was conducted to investigate the relations of axial force and deformational capacity of concrete-filled square steel tube columns. The test series consisting of 36 columns were tested under the constant axial load and horizontal cyclic load. The axial force of the columns that resisted under the cyclic lateral load was defined as a certified strength of limit axial force. The analytical model was defined as a cantilever beam-column. The axial force of the beam-column that resisted under the cyclic lateral load was defined as an accumulated certified strength of limit axial force. The purpose of this study is to investigate the certified strength of limit axial force of concrete-filled steel tube beam-columns, which were subjected to both axial and lateral load condition corresponding to a given constant rotation angle. Another purpose of this study is to discuss the comparison of the certified strength of limit axial force of concrete and the accumulated certified strength of limit axial force of concrete-filled steel tube columns.

• Magazine of the Korea Concrete Institute
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• v.7 no.5
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• pp.133-144
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• 1995

This study investigated to the properties of structural behaviors through a series of experiment with the key parameter, such as diameter-to-thickness(D/t) ratio, selenderness ratio of steel t~ube and strength of concrete under loading condition simple confined concrete by steel tube as a fundmental study on adaptability with structural members in high-rise building. The obtained results are sumnarised as follow. (1) The fracture mode of confined concrete was presented digonal tension fracture in the direction of $45^{\circ}$ with compression failure at the end of specimen in stub column, but the fracture mode of long column was assumed an aspect of bending fracture transversely. (2) The deformation capacity and ductility effect was increased by confine steel tube for concrete. (3) 'The emprical formula to predict the ultimate capacity of confined concrete by steel tube and concrete filled steel tube column using restraint of concrete considered D / t ratio, selenderness ratio of steel tube anti strength of' concrete were proposed.