• Steel and Composite Structures
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• 제4권1호
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• pp.37-48
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• 2004

This paper deals with the strength and deformation of both short and slender concrete filled steel tubular columns under the combined actions of axial compression and bending moment. Sixteen specimens were tested to investigate the effect of fiber reinforced concrete on the ultimate strength and behavior of the composite column. The primary test parameters were load eccentricity and column slenderness. Companion tests were also undertaken on eight numbers of similar empty steel tubes to highlight the synergistic effects of composite column. The test results demonstrate the influence of fiber reinforced concrete on the strength and behavior of concrete filled steel tubular columns.

• Steel and Composite Structures
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• 제41권5호
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• pp.663-679
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• 2021

To elucidate the differences in the collapse behavior between a single-story beam-column assembly and multi-story frame, two 1/3-scale two-bay composite frames, including a single-story composite beam-column assembly and a three-story composite sub-frame, were designed and quasi-statically tested. The load-displacement responses, failure modes, and internal force development of the two frames were analyzed and compared in detail. Furthermore, the resistance mechanisms of the two specimens were explored, and the respective contributions of different load-resisting mechanisms to the total resistances were quantitatively separated to gain deeper insights. The experimental tests indicated that Vierendeel action was present in the two-dimensional multi-story frames, which led to an uneven internal force distribution among the three stories. The collapse resistance of TSDWA-3S in the flexural stage was not significantly increased by the structural redundancy provided by the additional story, as compared to that of TSDWA-1S. Although the development of the load response was similar in the two specimens at flexural stage, the collapse mechanisms of the multi-story composite frame were much more complicated than those of the single-story beam-column assembly, and the combined action between stories was critical in determining the internal force redistribution and rebalancing of the remaining structure.

• Steel and Composite Structures
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• 제7권2호
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• pp.119-133
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• 2007

Based on stability theory of current rigid steel frames and using the three-column subassemblage model, the governing equations for determining the effective length factor (${\mu}$-factor) of the columns in semirigid composite frames are derived. The effects of the nonlinear moment-rotation characteristics of beam-to-column connections and composite action of slab are considered. Furthermore, using a two-bay three-storey composite frame with semi-rigid connections as an example, the effects of the non-linear moment-rotation characteristics of connections and load value on the ${\mu}$-factor are numerically studied and the ${\mu}$-factors obtained by the proposed method and Baraket-Chen's method are compared with those obtained by the exact finite element method. It was found that the proposed method has good accuracy and can be used in stability analysis of semi-rigid composite frames.

• International Journal of Concrete Structures and Materials
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• 제11권2호
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• pp.185-197
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• 2017

In this study, we propose a new equation that evaluates the shear strength of beam-column connections in reinforced concrete and steel beam (RCS) composite materials. This equation encompasses the effect of shear keys, extended face bearing plates (E-FBP), and transverse beams on connection shear strength, as well as the contribution of cover plates. Mobilization coefficients for beam-column connections in the RCS composite system are suggested. The proposed model, validated by statistical analysis, provided the strongest correlation with test results for connections containing both E-FBP and transverse beams. Additionally, our results indicated that Architectural Institute of Japan (AIJ) and Modified AIJ (M-AIJ) equations should be used carefully to evaluate the shear strength for connections that do not have E-FBP or transverse beams.

• 한국강구조학회 논문집
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• 제24권1호
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• pp.109-117
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• 2012

연구대상은 콘크리트 충전강관 (Concrete Filled steel tube)기둥과 보의 접합부를 합성반강접으로 적용한 구조물의 설계 적용에 관한 것이다. 합성반강접으로 기둥접합부의 강성을 조절함으로서 구조적 안전성을 확보하고 경제적인 부재를 적용하고자 하였다. 저층건물을 모멘트골조로 구조물의 안정성을 검토한 결과 합성작용으로 인하여 합성반강접을 이용하면 횡강성이 증대하여 저층건물의 경우 특별한 횡 보강재 없이 저항할 수 있음을 확인 하였다. 고층건물의 경우 모멘트골조가 횡저항 분담이 10%정도 되었으며 반강접 비율은 60%정도가 적절하였다. 경제적인 면에서 보 부재는 등분포하중이 작용하는 경우는 반강접 효과가 크나 집중하중이 작용하는 보는 반강접 효과가 크지 않았으며 등분포의 경우 60% 반강접이 단부 모멘트 저감에 따른 경제성이 가장 좋은 것으로 분석되었다. 단부 모멘트는 약 25% 감소되는 것을 확인 할 수 있었다.

• Steel and Composite Structures
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• 제1권3호
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• pp.355-376
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• 2001

An experimental research program on end-plate beam-to-column composite joints under cyclic loading is presented. The major focus relates to the identification of the contribution of the concrete confinement in composite columns to the behaviour of the joint, on internal nodes and external nodes, together with an assessment of degradation of strength and stiffness in successive loading cycles. From the experimental results it was possible to identify the various failure modes and to fit the corresponding hysteretic curves to the Richard-Abbott and Mazzolani models. These curve-fitting exercises highlighted the need to adapt both models, either for improved ease of application, or to deal with some aspects previously not covered by those models.

• Steel and Composite Structures
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• 제28권4호
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• pp.449-460
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• 2018

This paper reports the experimental results of three through bolt beam-column connections under pure shear forces using modified push-out tests. The investigated specimens include extended end-plates and six through-bolts connecting square concrete-filled steel tubular column (S-CFST) to steel beams. The main goal of this study is to investigate if and how the mechanical shear connectors, such as steel angles and stud bolts, contribute to the shear transfer mechanisms in the steel-concrete interface of the composite column. The contribution of shear studs and steel angles to improve the shear resistance of steel-concrete interface in through-bolt connections was investigated using tests. The results showed that their contribution is not significant when the beam-column connection is included in the push-out tests. The specimens failed by pure shear of the long bolts, and the ultimate load can be predicted using the shear resistance of the bolts under shear forces. The predicted values of load allowed obtaining a good agreement with the tests results.

• Steel and Composite Structures
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• 제47권3호
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• pp.423-436
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• 2023

In this research, we tested 10 simply supported concrete-encased composite columns under monotonic eccentric loads and investigated their shear behaviour. The specimens tested were two reinforced concrete specimens, three steel-reinforced concrete (SRC) specimens with an H-shaped steel section (also called a beam section), and five SRC specimens with a cruciform-shaped steel section (also called a column section). The experimental variables included the transverse steel shape's depth and the longitudinal steel flange's width. Experimental observations indicated the following. (1) The ultimate load-carrying capacity was controlled by web compression failure, defined as a situation where the concrete within the diagonal strut's upper end was crushed. (2) The composite effect was strong before the crushing of the concrete outside the steel shape. (3) We adjusted the softened strut-and-tie SRC (SST-SRC) model to yield more accurate strength predictions than those obtained using the strength superposition method. (4) The MSST-SRC model can more reasonably predict shear strength at an initial concrete softening load point. The rationality of the MSST-SRC model was inferred by experimentally observing shear behaviour, including concrete crushing and the point of sharp variation in the shear strain.

• 한국강구조학회 논문집
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• 제17권1호통권74호
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• pp.63-71
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• 2005

최근 기존의 합성 기둥들이 가지는 단점은 보완하고 장점은 유지시킬 수 있는 효율적인 기둥 시스템으로 철골-콘크리트 합성 기둥(SC 합성 기둥)에 대한 연구가 수행되고 있다. 본 연구자는 선행 실험 연구를 통해 SC 합성 기둥의 압축 내력을 평가하였지만, 실험실의 용량 부족으로 대형 기둥에서의 실험은 수행하지 못하였다. 따라서 이 연구에서는 실험 연구의 후속 연구로서 범용 유한요소 해석프로그램을 이용하여 콘크리트와 철골의 상호 작용 및 비조밀단면을 가진 철골 플랜지의 국부좌굴을 반영할 수 있도록 하였다. 이러한 유한요소해석 모델은 기 수행된 압축 실험값과 비교하여 적합성을 검증하였다. 또한 이렇게 검증된 해석적 모델을 이용하여 대형 크기의 기둥에 대해 비선형 해석을 수행하여 단면 증대에 따른 SC 합성 기둥의 비선형 거동에 대해 비교 분석하였다. 비선형 해석 결과 SC 합성 기둥의 철골 단면의 폭-두께비는 25.0을 초과하지 않아야 하고, 연결재의 단면적은 $0.025d{\cdot}t$ 이상, 연결재의 간격은 d/2 또는 최대 300mm이하로 설치하는 것이 바람직하다는 결론을 얻었다.

• Steel and Composite Structures
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• 제4권2호
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• pp.95-112
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• 2004

A series of tests was performed to consider the behaviour of short composite columns under axial compressive loading, covering a range of S275 and S355 grade steel square hollow section filled with normal and high strength concrete. The interaction between the steel and the concrete component is considered and the results show that concrete shrinkage has an effect on the axial strength of the column. Comparisons between Eurocode 4, ACI-318 and the Australian Standards with the findings of this research were made. Result showed the equation used by the ACI-318 and the proposed Australian Standards gave better predication for the axial capacity of concrete filled SHS columns than the Eurocode 4.