• 한국강구조학회 논문집
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• 제13권1호
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• pp.71-79
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• 2001

본 연구는 콘크리트 충전강관을 고층 건축구조물의 기둥부재로의 이용을 위한 연구의 일환으로 필자의 실험결과와 그동안 국내에서 발표된 콘크리트충전 강관 기둥에 관한 연구논문(1991.1~2000.6)의 실험결과 값을 데이터 베이스를 통해 콘크리트 충전으로 인한 내력 상승효과와 세장비에 따른 내력 등을 파악하여 다음과 같은 결론을 얻었다. 콘크리트 충전 강관 단주의 콘크리트 충전으로 인한 내력 상승효과는 단면형태에 따라 달리 나타나며, 누가강도에 비해 충전각형 강관은 1.102배 충전원형강관은 1.279배의 내력상승효과를 나타냈다. 압축력과 휨을 받는 콘크리트 충전강관의 폭-두께비는 국내의 비충전 강관의 폭-두께비에 비해 충전각형관은 1.3배 충전원형강관은 1.6배 이상 완화할 수 있음을 알 수있었다. 충전 효과를 고려한 중심축 하중을 받는 콘크리트 충전 강관 기둥의 내력식을 제안하였다. 실험데이트를 대표적인 복수강도 곡선인 SSRC 곡선 및 ECCS 곡선과 비교하였다.

• Computers and Concrete
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• 제33권6호
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• pp.643-658
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• 2024

To date, shell-solid and fibre element model analysis are the most commonly used methods to investigate the seismic performance of concrete-filled steel tube (CFST) bridge piers. However, most existing research does not consider the loss of bearing capacity caused by the fracture of the outer steel tube. To fill this knowledge gap, a refined finite element (FE) model considering the ductile damage of steel tubes and the behaviour of infilled concrete with cracks is established and verified against experimental results of unidirectional, bidirectional cyclic loading tests and pseudo-dynamic loading tests. In addition, a parametric study is conducted to investigate the seismic performance of CFST bridge piers with different concrete strength, steel strength, axial compression ratio, slenderness ratio and infilled concrete height using the proposed model. The validation shows that the proposed refined FE model can effectively simulate the residual displacement of CFST bridge piers subjected to highintensity earthquakes. The parametric analysis indicates that CFST piers hold sufficient strength reserves and sound deformation capacity and, thus, possess excellent application prospects for bridge construction in high-intensity areas.

• 한국방재학회 논문집
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• 제11권2호
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• pp.1-8
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• 2011

콘크리트 충전강관기둥부재는 내력 및 내화적 효과가 우수한 것으로 인식되고 있으며, 이에 관련된 연구가 지속되는 추세이다. 콘크리트는 강관내부에 충전, 구속되므로 구조적 성능이 유지되면서 열용량의 효과가 발휘되어야 일정 시간이상의 내화성능이 발현될 것으로 판단된다. 따라서 본 논문의 목적은 21 MPa의 일반 콘크리트와 40 MPa의 고강도 콘크리트의 내화성능에 기여하는 정도를 파악하고, 향후 공학적 내화설계의 기반자료 제공을 위하여 축력비 100%, 80%, 60% 및 50%를 재하하는 내화시험을 수행하여, 강재의 표면온도, 콘크리트의 온도를 측정하였다. 콘크리트가 충전된 강관기둥부재는 30분이상의 내화성능 되지 못하였으며, 이는 콘크리트의 조기 균열에 의한 내력적 성능저하로 판단되었다. 따라서 일정시간 이상의 내화성능 확보는 작용 하중비를 50 %이하로 설정하는 것이 권장되었다.

• Steel and Composite Structures
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• 제37권5호
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• pp.533-549
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• 2020

Recently, Concrete-filled double skin steel tubular (CFDST) columns have proven an exceptional structural resistance in terms of strength, stiffness, and ductility. However, the resistance of these column members can be severely affected by the type of loading in which bending stresses increase in direct proportion with axial load and eccentricity value. This paper presents a non-linear finite element based modeling approach that studies the behavior of slender CFDST columns under biaxial loading. Finite element models were calibrated based on the outcomes of experimental work done by other researchers. Results from simulations of slender CFDST columns under axial loading eccentric in one direction showed good agreement with the experimental response. The calibrated models are expanded to a total of thirty models that studies the behavior of slender CFDST columns under combined compression and biaxial bending. The influences of parameters that are usually found in practice are taken into consideration in this paper, namely, eccentricity-to-diameter (e/D) ratios, slenderness ratios, diameter-to-thickness (D/t) ratios, and steel contribution ratios. Finally, an analytical study based on current code provisions is conducted. It is concluded that South African national standards (2011) provided the most accurate results contrasted with the Eurocode 4 (2004) and American Institute of Steel Construction (2016) that are found to be conservative. Accordingly, correction factors are proposed to the current design guidelines to provide more satisfactory results.

• Steel and Composite Structures
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• 제44권1호
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• pp.141-154
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• 2022

This paper describes the experimental and numerical investigation on circular and octagonal CFDST short columns under concentric loading to study their responses to various internal circular steel tube sizes by the constant cross-sectional dimensions of the external circular and octagonal steel tube. The non-linear finite element analysis of circular and octagonal CFDST columns was executed using the ABAQUS to forecast and compare the axial behavior influenced by the various sizes of internal circular steel tubes. The study shows that the axial compressive strength and ductility of circular and octagonal CFDST columns were significantly influenced by inner steel tubes with the strengths of constituent materials.

• 한국구조물진단유지관리공학회 논문집
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• 제13권2호통권54호
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• pp.223-230
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• 2009

본 연구는 다양한 직경-두께비와 콘크리트 강도를 고려한 콘크리트 충전강관의 휨 거동을 다루었다. 유한 요소 해석을 위하여 상용 프로그램 LUSAS를 사용하였으며, 충전 강관의 콘크리트와 강 사이의 부착면의 상세거동을 고려하기 위하여 조인트 요소를 적용하였다. 또한, 콘크리트와 강관의 비선형성을 고려하기 위하여 소성영역에서 증가된 응력을 사용한 콘크리트와 강의 응력-변형률 곡선을 사용하였다. 제안된 방법으로 구한 수치해석 결과는 등분포하중을 받는 강관의 하중-변위 곡선에 대한 실제 실험 결과와 잘 일치하였다. 몇 가지 매개변수 연구는 서로 다른 직경-두께비와 콘크리트 강도에 대하여 휨 영향을 받는 콘크리트 충전강관의 구조적 특성에 초점을 두었다.

• Advances in concrete construction
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• 제8권4호
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• pp.257-267
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• 2019

This paper presents the results of cyclic loading tests on new high-strength concrete (HC) short columns. The seismic performance and deformation capacity of three reinforced high-strength concrete filled Polyvinyl Chloride tube (RHC-PVCT) short columns and one reinforced high-strength concrete (RHC), under pseudo-static tests (PSTs) with vertical axial force was evaluated. The main design parameters of the columns in the tests were the axial compression ratio, confinement type, concrete strength, height-diameter ratio of PVCT. The failure modes, hysteretic curves, skeleton curves of short columns were presented and analyzed. Placing PVCT in the RHC column could be remarkably improved the ultimate strength and energy dissipation of columns. However, no fiber element models have been formulated for computing the seismic responses of RHC-PVCT columns with PVT tubes filled with high-strength concrete. Nonlinear finite element method (FEM) was conducted to predict seismic behaviors. Finite element models were verified through a comparison of FEM results with experimental results. A parametric study was then performed using validated FEM models to investigate the effect of several parameters on the mechanical properties of RHC-PVCT short columns. The parameters study indicated that the concrete strength and the ratio of diameter to height affected the seismic performance of RHC-PVCT short column significantly.

• 한국강구조학회 논문집
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• 제27권4호
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• pp.399-410
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• 2015

콘크리트 충전형 합성기둥(Concrete filled steel tube, CFT)은 철근콘크리트, 강구조보다 뛰어난 변형 능력과 강도 갖고 있다. CFT 현장타설말뚝은 지진하중, 토양액상화 등에 의해 큰 국부전단력을 경험하게 되며 이를 방지하기 위해 큰 직경으로 설계되어 진다. 그러나 현행 기준의 전단 설계식은 CFT의 구속효과를 고려하지 못하고 있으며, 상당히 보수적인 설계식을 제시하고 있다. 전단 설계식의 개선을 위한 선행 전단 실험연구가 거의 없으며 그조차 소구경의 실험연구로만 존재한다. 이 연구는 대구경 콘크리트 충전형 합성기둥의 개선된 전단 설계식을 제안하기 위한 기초연구로써, 원형 CFT 기둥 전단의 선행 실험연구와 현행 설계기준 비교분석을 실행하였다.

• 한국디지털건축인테리어학회논문집
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• 제11권2호
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• pp.31-39
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• 2011

Concrete-filled steel tube(CFT) columns have become popular for building construction due to not only composite effect of steel tube and infilled concrete, but also more economical. The purpose of this paper is to propose the applicable boundary formula of width-to-thickness ratio for rectangular steel tube as using CFT column. A parametric study was performed taking width-to-thickness ratio of rectangular steel tube and compressive strength of concrete as the main parameter. The strength of concrete are selected to 30, 60, 90MPa. The non-linear analysis was adopted in order to take into account the effect of concrete strength. Finally, from the test and analysis results, the effect of increasing strength according to concrete strength and width-to-thickness of steel tube and plastic behavior of specimens were verified distinctly.

• Steel and Composite Structures
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• 제37권4호
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• pp.481-492
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• 2020

Twenty-two corrosion-damaged columns were simulated through accelerated steel corrosion tests. Eight specimens were directly tested to failure under axial load, and the remaining specimens were tested after concrete-filled steel tube (CFST) strengthening. This study aimed to investigate the damage of RC columns after corrosion and their restoration and enhancement after strengthening. The research parameters included different corrosion degrees of RC columns, diameter-to-thickness ratio of steel tube and the strengthening concrete strength. Experimental results showed that CFST strengthening method could change the failure mode of corrosion-damaged RC columns from brittleness to ductility. In addition to the bearing capacity provided by the strengthening materials, it can also provide an extra 26.7% amplification because of the effective confinement provided by steel tubes. The influence of corrosion on reinforcement and concrete was quantitatively analysed and considered in the design formula. The proposed formula accurately predicted the bearing capacity of the strengthened columns with a maximum error of only 7.68%.