• Journal of Korean Society of Steel Construction
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• v.19 no.6
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• pp.703-714
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• 2007

The aim of this research is to evaluate the fire resistance of concrete-filled steel square tube columns (square CFT columns) under constant axial loads by numerical analysis. The authors examined the experimental results on the fire resistance of concrete-filled steel square tube columns without fire protection. As the materials of CFT columns, steel of SPSR 400 grade and concrete of 27.5MPa and 37.8MPa strengths were used. The significant parameters were determined, such as load ratio, cross-sectional dimensions, and concrete strength. Detailed analytical simulations of fire resistance and axial deformation showed good agreement with the experimental observations. Therefore, this numerical analysis exhibited a reasonable estimation of fire resistance of the square CFT column. Results of the numerical parametric studies showed that the fire resistance of the CFT columns increased with the decrease of the concrete strength and the increase of the cross-sectional dimensions about the constant axial load ratio ($N/N_c$).

• Journal of Korean Society of Steel Construction
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• v.19 no.4
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• pp.425-434
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• 2007

The SC (steel-concrete) composite column was developed to take advantage of the relative economy of using concrete as opposed to steel in carrying large compressive forces. As the SC composite column is pre-fabricated, its use can minimize laborand can speed up the erection of a steel building. In this study, an experiment was conducted to analyze the influence of several parameters, such as the load ratio, the concrete ratio of an area, and its performance with or without fire protection, on the performance of the SC composite column. This paper proposes that the calculation of the strength reduction ratios of columns be done by increasing the temperature. Theoretical equations were used to evaluate the effectiveness of the fire resistance of the SC composite column, and the results of the test and analysis were compared. The fire resistance of the SC composite column was increased by decreasing its load ratio, but the concrete ratio of an area has minimal influence on the fire resistance of the SC composite column.

• 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 for Atmospheric Environment
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• v.21 no.2
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• pp.227-242
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• 2005

The aim of this study is to relieve the poor ventilation problem of the diesel locomotive engine load test building, located in an urban area. This paper evaluates the ventilation performances of the studied load test building based on the temperature measurement experiment and the computational fluid dynamics (CFD) during the engine load test. The temperature rise caused by the radiator blower of the building was turned out to be the main cause of disturbing the thermal conditions of the building. The indoor temperature distributions simulated by Fluent were validated with the temperature measurement results obtained from the studied building. The simulation results indicated that the comfort condition of this building was poor We suggested several remedial changes in the duct structure of this building for the improvement of the comfort conditions. In addition, a prototype drawing combining several improved design options was proposed. and then the simulation of the temperature distribution in the proposed prototype was performed. The result indicated that the indoor thermal condition of this proposed building was improved when compared with that of the current building.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.380-386
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• 2020

The ESS load test device (ELTD) can store and exchange electrical energy during the load test of an emergency generator. On the other hand, it is difficult to commercialize ELTDs based on Li-ion batteries because of the high initial cost, which is higher than a load bank test. If the trade of electrical energy stored in ELTD during the test of an emergency generator is considered, it may be possible to commercialize the ELTD. Therefore, this paper proposes an economic model of ELTD composed of the costs and benefits by considering electrical energy trade to perform accurately economic evaluations of an ELTD. From the simulation results of the economic evaluations of an ELTD and the load bank method, it was found that the commercialization of ELTD is possible when the trade in electrical energy in ELTDs is considered.

• Journal of Korean Society of Steel Construction
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• v.18 no.5
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• pp.643-654
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• 2006

Thispaper presents the results of an experimental investigation into the fire performances ofsimply supported iTECH composite beams using an ISO834 standard fire. There are very few independent studies on the fire resistance of composite steel and concrete structures of various designs. The iTECH composite beam system has been used in construction, but nothing is known about its influence in a fire. To evaluate the fire resistance performanceof the iTECH beam, a test was conducted for 4.7m-span-length iTECH beams under given conditions in a laboratory. The fire resistance performance of unprotected coatings of the iTECH beam has been examined, and a longer period of fire resistance was achieved by increasing the beam coating's section size and decreasing its load ratio. Coatings for the fire protection of iTECH beams reduce the rate of temperature rise of the beam in case of fire, and the required thickness of spray-on fire protection coatings can be determined by means of tests.

• International Journal of High-Rise Buildings
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• v.13 no.1
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• pp.85-95
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• 2024

A composite member made of concrete-filled steel tubes (CFT columns) has been recognized for its fire resistance due to the thermal mass effect of concrete inside the steel tube, as shown in various studies. In this study, the fire resistance performance of reinforced CFT columns under constant axial load was evaluated using finite element analysis with ABAQUS. For this purpose, the variables including cross-section size, steel tube thickness, and concrete cover thickness were set, and the temperature distribution in the column cross-section exposed to a standard fire was investigated using heat transfer analysis. Ultimately, a P-M interaction curve was obtained by evaluating the overall residual strength of columns, and the fire resistance time was determined by evaluating axial displacement-time responses due to the reduction in load capacity during fire through stress analysis.

• Journal of Korean Society of Steel Construction
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• v.20 no.5
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• pp.655-663
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• 2008

In this research, the fire resistance of Concrete-Filled Circular Steel Tube Columns (CFT) was evaluated by numerical analysis. As the materials of CFT columns, the steel of SPSR 400 grade and the concrete of 27.5MPa, 37.8MPa strengths were used. Significant parameters,such as concrete strength, axial load, and cross-sectional dimensions were determined. To verify the accuracy of the numerical analysis,the analysis results were compared with the former experiment results. The effect of the fire resistance time, axial load ratio, cross-sectional dimensions and concrete strength was evaluated by comparison with the fire resistance of the square CFT columns. This research showed that the structural behavior and fire resistance from the findings of numerical parametric studies showed a similarity to that of the experimental results. Therefore, this numerical analysis is reasonable in estimating the fire resistance of the circular CFT column.

• Journal of Korean Society of Steel Construction
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• v.22 no.6
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• pp.581-588
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• 2010

Recently the requirements of the buildings built with structural steel were increased in terms of structural stabilities and fire resistance at severe fire conditions. To meet the building regulations of fire resistance, a fire design is needed. This is of a prescriptive method and a performance engineering based method. Recently a simple calculation method as one of performance based engineering method is very popular because of its ease for an application in building built with structural steel. But, in Korea the performance based engineering method is not allowed yet. Thus it is needed to make a guideline for the performance based engineering method. The purpose of this study is to establish the limit temperature derived from structural beams made with both a H-section and a H-section filled with concrete at the web and derived the limit temperatures from beams made with H-sections and found out that the limit temperatures from two kinds of specimens depended on the applied loads and the specimens filled with the concrete represented 3 hour fire resistance in the range of 80%, 60%, and 50% of the maximum load.

• Fire Science and Engineering
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• v.29 no.4
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• pp.33-38
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• 2015

Loads applied on the floor are transferred through beams to columns. The beams can be designed as both end fixed or simple beams. The load bearing capacity of a beam depends on each boundary condition. However, when the load bearing capacity of a beam is evaluated in fire tests, all kinds of beams are tested using simple beam conditions. In this study, an analytical method performed using heat transfer theory and heat stress analysis based on the mechanical and thermal properties of SS-400 steel at high temperature. This method was used to clarify the differences between the two types of boundary conditions at normal and high temperature. The results show that the load bearing capacity of a both-end fixed beam at high temperature is superior to that of a simple beam. Therefore, the application of simple beam conditions in fire tests for evaluation of load bearing capacity is conservatively safe compared to fixed boundary conditions.