• Fire Science and Engineering
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• v.24 no.6
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• pp.69-75
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• 2010

A concrete filled square steel tube (CFT) is composed of the external steel material, which its strength is reduced in fire due to sudden temperature increase, and the internal concrete with high thermal capacity that can ensure the fire resistance performance of the structure. Therefore, research about the influence factors of the structural performance of CFT column is required in order to apply CFT column to a fire resisting structure, and additional research about influence for each condition is also necessary. Among the influence factors, the boundary condition between column and beam is important structurally, and it is one of the major factors that determine overall fire resisting performance. This study performed a fire experiment under loading in order to analyse the influences of CFT column to the boundary condition. As the results of the experiment, fire resistance time of 106 minutes was ensured for the clamped-end condition but 89 minutes for the hinge-end condition in case of the 360 cross section. And, fire resistance time of 113 minutes was ensured for the clamped-end condition but 78 minutes for the hinge-end condition in case of the 280 cross section.

• Computers and Concrete
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• v.9 no.4
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• pp.257-273
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• 2012

Based on the heterogeneous characterization of concrete at mesoscopic level, Realistic Failure Process Analysis ($RFPA^{3D}$) code is used to simulate the failure process of concrete-filled tubular (CFT) stub columns. The results obtained from the numerical simulations are firstly verified against the existing experimental results. An extensive parametric study is conducted to investigate the effects of different concrete strength on the behaviour and load-bearing capacity of the CFT stub columns. The strength of concrete considered in this study ranges from 30 to 110 MPa. Both the load-bearing capacity and load-displacement curves of CFT columns are evaluated. In particular, the crack propagation during the deformation and failure processes of the columns is predicted and the associated mechanisms related to the increased load-bearing capacity of the columns are clarified. The numerical results indicate that there are two mechanisms controlling the failure of the CFT columns. For the CFT columns with the lower concrete strength, they damage when the steel tube yields at first. By contrast, for the columns with high concrete strength it is the damage of concrete that controls the overall loading capacity of the CFT columns. The simulation results also demonstrate that $RFPA^{3D}$ is not only a useful and effective tool to simulate the concrete-filled steel tubular columns, but also a valuable reference for the practice of engineering design.

• Asia Marketing Journal
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• v.7 no.1
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• pp.43-65
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• 2005

In most leading companies, new product development is one of the most important corporate activities which affects the very existence of them. Therefore, CFT(cross-functional team) is frequently used to utilize knowledge and experiences of its members from various teams. To ensure the successful operation of CFT, various structural assistances, such as committee and Task Force Team, are made which will coordinate smooth interactions among members. Many researches show that the increase of interaction among team members affects the performance. This research is exploratory research intend to show the effects of relational characteristics such as group efficacy and participation on the perceived performance of new product development. This research examines the performance mechanism that lies in between CFT and its members by expanding the understandings on the relationship between interaction and performance in new product development CFT. Results show that the level of interaction affect group efficacy. and group efficacy affect participation. Finally, participation affect perceived performance. However. it shows that the level of interaction and group efficacy do not have direct effect on perceived performance.

• 한국방재학회:학술대회논문집
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• 2009.02b
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• pp.132.1-132.1
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• 2009

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.757-762
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• 2001

CFT concrete has high flowing, high strength and resistance to material separation to use skyscraper structure. It is considered that concrete could fill the lower part of Diaphragm up. This kinds of CFT concrete hardly apply to building below 20 stories. Using the common use strength concrete to building below 20 stories brings to reduce construction cost. This concrete is needed that valid fluidity and packing ability with unit cement content as common use strength concrete. Offering a fundamental data and proportioning in CFT concrete of below 20 stories, it is executed basic property test, analysis of proportioning and mock up test.

• Steel and Composite Structures
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• v.10 no.5
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• pp.415-428
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• 2010

Proper material constitutive models for concrete-filled tube (CFT) columns of circular cross section and subjected to pure bending moment are proposed. These material models are implemented into the Abaqus finite element program and verified against experimental data. It has been shown that the steel tube does not provide good confining effect to the concrete core when the CFT columns is subjected to pure bending moment. When the diameter-to-thickness ratio of the CFT columns is small, the behavior of the CFT column is the same as the steel tube without a concrete core.

• Steel and Composite Structures
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• v.24 no.3
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• pp.309-322
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• 2017

This paper conducted both numerical and theoretical studies to investigate the composite action of notched circular concrete-filled steel tubular (CFT) stub columns under axial compression and established a theoretical method to predict their ultimate bearing capacity. 3D finite element (FE) analysis was conducted to simulate the composite action and the results were in good agreement with experimental results on circular CFT stub columns with differently oriented notches in steel tubes. Parametric study was conducted to understand the effects of different parameters on the mechanical behavior of circular CFT stub columns and also the composite action between the steel tube and the core concrete. Based on the results, a theoretical formula was proposed to calculate the ultimate bearing capacity of notched CFT stub columns under compression with consideration of the composite action between the steel tube and the core concrete.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.203-210
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• 2005

This paper summarizes full-scale test results on CFT column to flat plate connections subjected to gravity loading. CFT construction has gained wide acceptance in a relatively short time in domestic building practice due to its various structural and construction advantages. Constructing the floor as flat plate is often regarded as being essential for both cost savings and rapid construction. However, efficient details for CFT column to flat plate connections have not been proposed yet, and their development is urgently needed. Based on some strategies that include maximizing economical field construction, several connecting schemes were proposed and tested in this study. Test results showed the proposed connection details can exhibit strength and stiffness comparable to or greater than those of R/C flat plate counterpart.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.179-180
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• 2018

This study aims to provide a more comfortable environment for the external environment by designing a rotable dwelling that deviates from the conventional fixed residential concept. The round pillars, which are the center of the building, are constructed by placing the CFT (concrete Filled steel Tube) technique in place and assembling modular houses with columns. This study combines existing building techniques. Korea also needs to develop various related studies quickly.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.101-102
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• 2018

There is a risk that the damage caused by frequent earthquakes can lead to the risk of personal injury due to cracks in buildings and collapse of major structures. Although the seismic design of the new building is designed to be reinforced, the existing structure is not exposed to the risk of earthquake. Therefore, it is aimed to develop the steel frame type CFT composite method which can easily reinforce the CFT structural system with excellent seismic performance against the old non - seismic structure.