• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2014년도 추계 학술논문 발표대회
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• pp.119-120
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• 2014

In this study, we looked into the method to establish fire growth rate by buildings use for growing fire at the beginning of a fire considering the characteristics of the combustibles in a performance-based design. Actual conditions survey and literature review were carried out for the fire load and exposed surface area of combustibles to establish design fire by domestic building use. As a results, a simplified prediction equation of fire growth rate which depends on fire load and weight of combustibles could be derived by calculating the relation between the fire load and the fire growth rate of an initial fire through investigation of combustibles by domestic building use.Also, as a result of analyzing the placement of combustibles and location of the ignition source, it was found that the influence of the materials of the combustibles and the materials of the combustibles adjacent to the ignition source is big. Though 4 different experiments were carried out for the evaluation, the result of comparing the findings with those of FGR model showed that the fire growth rate was similarly derived.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2012년도 춘계 학술논문 발표대회
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• pp.331-332
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• 2012

Structural steel has been used as a primary materials to columns and beams since 1960's in Korea with an advantages of excellent of load-bearing capacity and design flexibility, and faster construction. However, if the steel columns made of structural steel exposed to fire the load-bearing capacity is going down steadily and finally reach to collapse. Therefore, building regulation requires fire resistance according to building occupation, scales. The fire resistance can be evaluated two categories. One is prescriptive method that is based on building regulation, specification and so on and the other is performance-based fire engineering method. The latter can be designed based on scientific and engineering consequences. The easiest evaluation way using the fire engineering design is comparing to the limiting temperature and maximum temperature calculated based on heat transfer theory. If the limiting temperature of a column exceeds the maximum temperature of it, the column can carry the load during the fire. Therefore, the database of limiting temperature is very essential for evaluation of column. In this paper, to build the database of column made of rectangular hollow sections 8 fire tests with loading were conducted and the relation between the limiting temperature and the applied loads showed in reverse proportion.

• 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.

• 한국화재소방학회논문지
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• 제24권6호
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• pp.104-111
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• 2010

CFT기둥은 강관내부에 콘크리트를 채워 넣은 구조로서, 화재 시 강관의 강도는 저하되나 내부 콘크리트의 높은 열용량 효과로 내화성능을 확보할 수 있는 구조이다. 본 연구에서는 강관내부의 충전된 콘크리트의 압축강도 및 축력비 변화에 따른 CFT기둥의 내화성능을 평가하였다. 내화성능의 평가는 KS F 2257-1 및 KS F 2257-7에 따라 수행되었으며, 적용 부재 단면은 $280{\times}280{\times}6$, 콘크리트 압축강도 24MPa, 40MPa 및 축력비 0.9, 0.6, 0.2를 실험변수로 설정하였다. 재하가열시험을 통한 내화성능평가 결과, 콘크리트 압축강도 24Mpa의 경우 축력비 0.9, 0.6, 0.2에서는 각각 27분, 113분, 3시간 이상으로 나타나 축력비 변화에 따른 내화성능이 크게 변화하는 것으로 나타났다. 콘크리트 압축강도 40MPa의 경우, 축력비 0.9, 0.6에서는 각각 19분, 28분으로 나타났다. 40MPa는 24MPa에 비해서 축력비 변화에 따른 내화성능 향상 효과는 크지 않은 것으로 나타났다. 이는 고강도의 경우 가열시 발생되는 내부 압력의 상승로 성능저하가 크게 발생되는 것으로 판단되었다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 추계 학술논문 발표대회
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• pp.149-150
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• 2015

Structural beam plays a key role to carry the applied load on the floors. And then the beam have to sustain the applied load and its load-bearing capacity in fire situation. In this study to know the fire resistance performance of long span beam made of a submarine structural steels, an engineering method is used using mechanical and thermal properties of structural steel at high temperature.

• 한국구조물진단유지관리공학회 논문집
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• 제11권2호
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• pp.109-116
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• 2007

본 논문의 목적은 경량기포모르터를 충전한 스틸스터드와 복합스터드 내력벽체의 내화성능을 KS규준에 따라 평가하는데 있다. 주거용과 상업용 건물의 최소 내화 요구시간은 2시간이다. 시험 결과로부터 스틸 스터드와 복합스터드에 경량기포 모르터를 충전한 두 시험체 모두 2시간 내화 성능을 만족하는 것으로 나타났다. 또한 복합스터드 패널 시험체의 경우 내화 성능면에서 스틸 스터드 패널 시험체 보다 우수하다는 것을 정량적 평가하였다.

• 한국화재소방학회논문지
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• 제31권6호
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• pp.16-22
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• 2017

국내에서는 복잡해지고 다양해지고 있는 건축물에서의 화재위험에 대응하기 위해 성능기반 화재안전 설계가 논의되고 있지만, 건축물에서의 다양한 인자들에 의한 화재특성의 에측의 어려움으로 인하여 성능기반 화재안전 설계의 도입이 제한되고 있다. 본 연구에서는 뉴질랜드에서 제시하고 있는 화재위험도별 화재하중 값의 실대형 화재실험을 통해 성능기반 설계 도입을 위한 기준 방향 설정 및 기초 자료로 사용하고자 하였다. 실대형 화재실험은 10 MW급의 실대형 칼로리미터에서 $0.8(L){\times}2.0(H)m$의 단일 개구부를 포함하고 있는 $2.4(L){\times}3.6(W){\times}2.4(H)m$ 크기의 시험체 틀의 내부에 목재 크립을 화재하중에 따라 배치시켜, 목재 크립이 전소할 때 까지 진행하였다. 화재실험에서 열방출률의 변화는 목재 크립에 화염이 착화 된 후 외부로 출화되는 약 90초 이후부터 급격히 증가하였으며, 위험도 레벨 1에서는 최대 4743.4 kW의 열발출률이 실험시작 후 244 초에 측정되었고 위험도 레벨 2에서는 5050.9 kW의 최대 열방출률이 497 초에 측정되었다. 또한 위험도 레벨 3에서는 최대 열방출률이 4446.9 kW로 실험시작 677 초에 측정되었다.

• Structural Engineering and Mechanics
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• 제50권6호
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• pp.755-772
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• 2014

A simplistic approach towards evaluation of complete load deflection response of Reinforced Concrete (RC) flexural members under post fire (residual) scenario is presented in this paper. The cross-section of the RC flexural member is divided into a number of sectors. Thermal analysis is performed to determine the temperature distribution across the section, for given fire duration. Temperature-dependent stress-strain curves for concrete and steel are then utilized to perform a moment-curvature analysis. The moment-curvature relationships are obtained for beams exposed to different fire durations. These are then utilized to obtain the load-deflection plots following pushover analysis. Moreover one of the important issues of modeling the initial stiffness giving due consideration to stiffness degradation due to material degradation and thermal cracking has also been addressed in a rational manner. The approach is straightforward and can be easily programmed in spreadsheets. The presented approach has been validated against the experiments, available in literature, on RC beam subjected to different fire durations viz. 1hr, 1.5hrs and 2hrs. Complete load-deflection curves have been obtained and compared with experimentally reported counterparts. The results also show a good match with the results obtained using more complicated approaches such as those involving Finite element (FE) modeling and conducting a transient thermal stress analysis. Further evaluation of the beams during fire (at elevated temperatures) was performed and a comparison of the mechanical behavior of RC beams under post fire and during fire scenarios is made. Detailed formulations, assumptions and step by step approach are reported in the paper. Due to the simplicity and ease of implementation, this approach can be used for evaluation of global performance of fire affected structures.

• Structural Engineering and Mechanics
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• 제7권2호
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• pp.127-145
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• 1999

This paper deals with the development of an approach for evaluating the squash load and rigidity of unprotected concrete filled steel columns at elevated temperatures. The current approach of evaluating these properties is reviewed. It is shown that with a non-uniform temperature distribution, over the composite cross-section, the calculations for the squash load and rigidity are tedious in the current method. A simplified approach is proposed to evaluate the temperature distribution, squash load, and rigidity of composite columns. This approach is based on the model in Eurocode 4 and can conveniently be used to calculate the resistance to axial compression of a concrete filled steel column for any fire resistance time. The accuracy of the proposed approach is assessed by comparing the predicted strengths against the results of fire tests on concrete filled circular and square steel columns. The applicability of the proposed approach to a design situation is illustrated through a numerical example.

• Advances in concrete construction
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• 제10권4호
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• pp.289-299
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• 2020

A reliability analysis of the axial compressive load bearing capacity of postfire reinforced concrete (RC) columns strengthened with carbon fiber reinforced polymer (CFRP) sheets was presented. A 3D finite element (FE) model was built for heat transfer analysis using software ABAQUS. Based on the temperature distribution obtained from the FE analysis, the residual axial compressive load bearing capacity of RC columns was worked out using the section method. Formulas for calculating the residual axial compressive load bearing capacity of the columns after fire exposure and the axial compressive load bearing capacity of postfire columns retrofitted with CFRP sheets were developed. Then the Monte Carlo method was used to analyze the reliability of the axial compressive load bearing capacity of the RC columns retrofitted with CFRP sheets using a code developed in MATLAB. The effects of fire exposure time, load ratio, number of CFRP layers, concrete cover thickness, and longitudinal reinforcement ratio on the reliability of the axial compressive load bearing capacity of the columns after fire were investigated. The results show that within 60 minutes of fire exposure time, the reliability index of the RC columns after retrofitting with two layers of CFRPs can meet the requirements of Chinese code GB 50068 (GB 2001) for safety level II. This method is effective and accurate for the reliability analysis of the axial load bearing capacity of postfire reinforced concrete columns retrofitted with CFRP.