• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1995년도 가을 학술발표회 논문집
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• pp.210-214
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• 1995

Research on concrete-filled steel columns has been conducted. It is also well known that the load and deformation capacity of concrete-filled steel columns are considerable larger than those of widely used reinforced concrete columns and steel encased concrete columns because the concrete core in the steel is confined laterally by the steel. But, most of these works focused on columns with strength enhancement by the confinement effect, so that no local buckling prevented by the concrete. columns because the concrete core in the steel is confined laterally by the steel. But, most of these works focused on columns with strength enhancement by the confinement effect, so that no local buckling prevented by the concrete. This paper, therefore, presents on the stress-strain relation of a concrete filled rectangular steel tube under axial compression. As the results, the axial load verse average axial strain relationship of concrete-filled rectangular steel columns were very stable. The small B/t ratios in concrete-filled rectangular steel columns aren't affected prevention of local buckling but strength enhancement by confinement effect.

• 한국공간구조학회논문집
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• 제6권1호
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• pp.55-63
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• 2006

본 논문은 콘크리트 충전 원형 및 각형 합성 강관을 기둥부재로서의 적합성 및 적용성을 위한 연구로 두개의 강관을 합성한 콘크리트 충전 강관 기둥의 축압축 좌굴내력 및 변형형상에 대한 실험적 연구이다. 강관 기둥에 대한 연구는 콘크리트 충전 원형 강관 기둥, 콘크리트 충전 각형 강관 기둥, 콘크리트 충전 합성 강관 기둥으로 분류하여 실험을 수행하였다.

• Steel and Composite Structures
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• 제23권5호
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• pp.611-621
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• 2017

This paper presents an investigation on the fire resistance of high strength fiber reinforced concrete filled box columns (CFBCs) under combined temperature and loading. Two groups of full-size specimens were fabricated. The control group was a steel box filled with high-strength concrete (HSC), while the experimental group consisted of a steel box filled with high strength fiber concrete (HFC) and two steel boxes filled with fiber reinforced concrete. Prior to fire test, a constant compressive load (i.e., load level for fire design) was applied to the column specimens. Thermal load was then applied on the column specimens in form of ISO 834 standard fire curve in a large-scale laboratory furnace until the set experiment termination condition was reached. The test results show that filling fiber concrete can improve the fire resistance of CFBC. Moreover, the configuration of longitudinal reinforcements and transverse stirrups can significantly improve the fire resistance of CFBCs.

• Steel and Composite Structures
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• 제15권6호
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• pp.645-658
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• 2013

The objective of the study is to predict the moment anchorage capacity of the concrete filled steel box (CFSB) as footing by using the 3D finite element program CAMUI developed by authors' laboratory. The steel box is filled with concrete and concrete filled steel tube (CFT) column is inserted in the box. Numerical simulation of the experimental specimens was carried out after introducing the new constitutive model for post peak behavior of concrete in compression under confinement. The experimental program was conducted to verify the reliability of the simulation results by the FE program. The simulated peak loads agree reasonably with the experimental ones and was controlled by concrete crushing near the column. After confirming the reliability of the FEM simulation, effects of different parameters on the moment anchorage capacity of concrete filled steel box footing were clarified by conducting numerically parametric study.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.217-220
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• 2008

구조물의 시공에 있어 더욱 경제적이고 안정적인 결과를 얻기 위해 최근 전 세계적으로 고성능 콘크리트와 복합재료에 관한 연구가 활발히 이루어지고 있다. 그 중 하나로 대구경의 강관 내부를 콘크리트계 재료로 충전하여 충전재간의 상호 구속효과(Confinement effect)로 인해 부재의 변형성능과 강성 및 내력을 향상시키는 콘크리트 충전 강관구조(Concrete Filled Steel Tubular Structure, CFT구조)에 아치구조 효과와 강선 등을 이용한 프리스트레스 구조를 도입하여, 구조적, 경제적 효율성을 극대화 시킨 새로운 형식의 거더인 CFTA 거더(Concrete Filled and Tied Steel Tubular Arch 거더)가 있다. 본 연구에서는 구조해석 프로그램인 ABAQUS 6.5-1을 사용하여 CFTA 거더에 일반 콘크리트와 여러 강도의 고강도 콘크리트를 충전한 모델의 비선형 거동을 분석하고 각각의 결과를 비교 분석하였다.

• 한국강구조학회 논문집
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• 제8권4호통권29호
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• pp.59-76
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• 1996

Concrete filled steel tube column has a large load carrying capacity through its steel and concrete interaction which makes it useful in construction. However, it has not been used often in a practical construction field. This is partly due to the non-destructive inspection method for concrete filling which has yet to be established. Furthermore, there are the lack of test data and a practical method in evaluating the ultimate load carrying capacity of concrete filled steel tube column. This paper will attempt to predict the ultimate strength of short concrete filled square tubular steel columns through conducting several tests. To accumulate the new test data on concrete filled steel tube columns, a total of 42 specimens of steel tubular columns were monotonically tested under concentric axial force, having the slenderness ratio(${\lambda}=10,\;15,\;20$), width-thickness ratio(d/t=25.0, 33.3) and concrete strengths($F_{c}=210,\;240,\;270kg/cm^{2}$). The hollow sections and concrete filled steel columns were compared to check the lateral confinded effects by steel tube. Through these test results, we propose a coefficient k=3.64 for the strength evaluation formula(10) of concrte filled tubular steel short columns.

• Steel and Composite Structures
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• 제21권6호
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• pp.1227-1250
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• 2016

Most of the research work has been conducted on K-joints under static loading. Very limited information is available in consideration of fatigue strength of K-joints with concrete-filled chord. This paper aims to describe experimental and numerical investigations on stress concentration factors (SCFs) of concrete-filled circular chord and square braces K-joints under balanced axial loading. Experiment was conducted to study the hot spot stress distribution along the intersection of chord and braces in the two specimens with compacting concrete filled in the chord. The test results of stress distribution curves of two specimens were reported. SCFs of concrete-filled circular chord and square braces K-joints were lower than those of corresponding hollow circular chord and square brace K-joints. The corresponding finite element analysis was also conducted to simulate stress distribution along the brace and chord intersection region of joints. It was achieved that experimental and finite element analysis results had good agreement. Therefore, an extensive parametric study was carried out by using the calibrated finite element model to evaluate the effects of main geometric parameters and concrete strength on the behavior of concrete-filled circular chord and square braces K-joints under balanced axial loading. The SCFs at the hot spot locations obtained from ABAQUS were compared with those calculated by using design formula given in the CIDECT for hollow SHS-SHS K-joints. CIDECT Design Guide was generally quite conservative for predicting SCFs of braces and was dangerous for predicting SCFs of chord in concrete-filled circular chord and square braces K-joints. Finally SCF formulae were proposed for circular chord and square braces K-joints with concrete-filled in the chord under balanced axial loading. It is shown that the SCFs calculated from the proposed design equation are generally in agreement with the values derived from finite element analysis, which were proved to be reliable and accurate.

• 한국강구조학회 논문집
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• 제10권2호통권35호
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• pp.177-186
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• 1998

콘크리트 충전 강관 기둥은 동일 단면의 비충전 강관 기둥에 비해 압축 내력이 우수하며 충전 콘크리트에 의한 강성의 향상, 국부좌굴 보강 효과에 의한 인성의 향상 등과 같은 구조적으로 우수한 점이 많다. 그러나. 강관과 충전 콘크리트의 상호작용 효과, 응력 분담율, 콘크리트의 파괴 양상 등에 대해서는 불분명한 점들이 많다. 본 연구는 일련의 실험을 통하여 고강도 콘크리트 충전 강관 기둥에 대해 재하 조건에 따른 구조적인 거동 특성에 대해 고찰하였다. 특히, 본 연구에서는 재하조건에 따른 강관과 콘크리트의 응력 분담율, 충전 콘크리트의 파괴 양상등에 대해 조사 하였다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2000
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• pp.151-158
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• 2000

In this paper, It is presented that concrete-filled composite piers have large energy-absorption capacity and high strength and stiffness on account of mutual confinement between the steel plate and filled-in concrete. Concrete-filled composite columns were tested to failure under axial compression and cyclic lateral loading. Displacement ductility index obtained by using the load-displacement relation has been increased with the increment of filled-in concrete length, while it has been decreased according to the incrementation of width-thickness ratio, slenderness ratio and the number of loading cycles. Structural behavior and ductility index estimated for the seismic design showed that composite piers could be used as a very efficient earthquake-resistant structural member. The response modification factor could be re-evaluated for concrete-filled composite piers.

• Steel and Composite Structures
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• 제22권4호
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• pp.821-835
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• 2016

The paper presents an experimental study of the structural behavior of circular flyash-concrete-filled steel tubular stub columns under axial compressive loads. In this study, 90% and 100% by weight of the cement in the concrete core was replaced with flyash. Twenty-seven specimens were tested to study the influence of flyash content, wall thickness of the steel tube, and curing age on the ultimate capacity and confinement effect. The experimental results were compared with the design values calculated using AISC-LRFD (1999), ACI (1999), AIJ (1997) and Eurocode 4 (1994). From the experimental study, it was determined that the confinement effect of circular steel tubes filled with high content flyash concrete was better than that of specimens filled with ordinary Portland cement concrete. The 5.88-mm-thick steel tube filled with 100% flyash concrete was equivalent in strength to a steel tube filled with C30 concrete at 28 days.