• Journal of Korean Society of Steel Construction
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• v.10 no.4 s.37
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• pp.741-748
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• 1998

Experimental studies were carried out with test parameters: diaphragm yield type and beam yield type, the opening hole size of inner steel diaphragm, and the existence of slab in order to understand the behavior of beam-to-concrete filled steel tube column rigid connections under cyclic loading condition. Test results show that the connections have good rotational capacity when the beam yields first and the joints should be designed such that the beam yields prior to the inner diaphragms.

• 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.

• Journal of Korean Society of Steel Construction
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• v.24 no.1
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• pp.81-89
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• 2012

The concrete-filled tubular square column is superior to steel frame column in terms of fire resistance because of the thermal storage provided by the concrete. Studies have been conducted on CFT column reinforcement with steel bars or with the use of an internal tube to improve its structural load capacity and fire resistance. In fact, reinforced CFT columns have been increasingly used to deal with high axial force. The functional deterioration of columns due to fire damage needs to be measured precisely. In this study, the temperature distribution inside the columns in case of a fire was evaluated and the degree of deterioration in the load capacity of the concrete and reinforcing members associated with temperature distribution was identified in order to evaluate the overall residual strength of the columns.

• Journal of Korean Society of Steel Construction
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• v.25 no.4
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• pp.347-357
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• 2013

Recently, In recognition of outstanding structural performance the use of Concrete Filled steel Tube(CFT) columns has been increased. Research is ongoing that effective use of cross-sectional because steel strength development and rising prices. In this Lab, suggests new shape by Thin steel plates bent to be L-channel welded to form square steel tube to maximize efficiency of the cross section. In addition, since the rib placed at the center of the tube width acts as an anchor; higher load capacity of buckling is acceptable. we have developed New shape welded built-up square tube for broader usability which were bent to be L-shaped and thin Plate each unit member were welded. In order to apply the new shape built-up square columns, we predicted structure behavior, stress distribution with parameter Width thickness ratio. The experimental results presented in standards and even exceed the b/t of the rib anchors installed in the role due to exert enough strength and deformation to improve performance was favorable.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2010.10a
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• pp.29-32
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• 2010

콘크리트 충전 강관기둥부재(이하 CFST)는 대칭성을 유지하는 기하학적 특성과 내부에 충전된 콘크리트의 구조 및 내화성능의 향상으로 최근 초고층 건축물의 주요 요소로 활용되는 추세에 있다. 반면 CFST는 실험적 결과에 의존하는 경향을 보이고 있으나 이는 많은 비용과 시간이 소요되는 단점이 있으므로 강재의 고온특성을 적용한 해석적 결과와의 상관성은 매우 중요한 의미가 있다. 따라서 본 연구의 목적은 CFST 내화성능을 해석 및 실험결과를 활용하여 상호 관계를 파악하고자 한다.

• Journal of Korean Society of Steel Construction
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• v.20 no.6
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• pp.711-722
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• 2008

Existing tube for concrete filled tubular structure is made through welding of four plates irrespective of tube thickness, so production performance is poor and special welding technique is needed to weld the internal diaphragm and through the diaphragm. Therefore, through manufacturing by cold forming development of beam to column connections that is no welding in position of stress concentration is needed. In this study the proposal of beam to column connections details and to making tube specimens by method of bending steel plates, we want to know the compositeeffect between internal anchor and concrete by processing on stress distribution and internal force evaluation of concrete filled tube beam to column connections with a variable of flange welding existence between column and beam, welding quantity between column and diaphragm, existence of concrete in tube, column with diaphragm and general column.

• Journal of Korean Society of Steel Construction
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• v.11 no.2 s.39
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• pp.233-240
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• 1999

It is well known that the ultimate compressive strength of concrete filled tubular stub-column is higher than that of the simplified evaluating value because of the confinement effect of infilled concrete. In this paper, It is compared the experimental results of other researchers with estimated ones by using the formulae. Finally, It is shown that the predicted equation is obtained by using the numerical analysis.

• Journal of the Korea Concrete Institute
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• v.25 no.1
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• pp.91-98
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• 2013

The pre-tensioned spun high strength concrete (PHC) pile has poor load carrying capacity in shear and flexure, while showing excellent axial load bearing capacity. The purpose of this study is to evaluate the flexural performance of the concrete-infilled composite PHC (ICP) pile which is the PHC pile reinforced with infilled concrete, transverse and longitudinal reinforcement for the improvement of shear and flexural load carrying capacity. The ICP pile specimen was designed to make allowable axial compression and bending moment higher load bearing capacity than those determined through the investigation of abutment design cases. The allowable axial compression and bending moment of the ICP pile was obtained using the program developed for calculating the axial compression - bending moment interaction. Then, ICP pile specimens were manufactured and flexural tests were performed. From the test results, it was found that the maximum bending moment of the ICP pile was approximately 45% higher than that of the PHC pile and the safety factor of ICP pile design was about 4.5 when the allowable bending moment was determined to be 25% of the flexural strength.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.2
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• pp.1-8
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• 2011

Concrete filled steel tubes(CFST) is considered as a column having better structural stability and better performance of fire resistance than that made with H-section and hollow section in itself. To get the fire resistance of the CFST, two kinds of concrete strength were used, 21 MPa, 40 MPa and 4 sorts of the applied loads were calculated and used to the specimens such as 3.5 m long, round and rectangular section. After various fire tests under 4 sorts of load ratios, the fire resistance of the CFST is not possible to get over 1 hour because of the rapid decrease of concrete strength. The below 50% of the applied load is recommended to obtain over 1 hour fire resistance of the CFST.

• Journal of Korean Society of Steel Construction
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• v.19 no.1
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• pp.53-65
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• 2007

Column tests were performed for a new type of column, the internally confined hollow concrete filled tube column (ICH CFT column), to evaluate its seismic performance. The seismic performances for two types of ICH CFT columns and a general solid RC column were evaluated and compared by quasi-static tests. The displacements and the lateral loads of column specimens were measured during tests. Ductilities, absorbed energy, equivalent damping ratios, damage indices were calculated from recorded data. From the test results, the ICH CFT column shows superior seismic performances with double moment capacity and larger energy absorbing capacity over that of a solid RC column.