• International Journal of High-Rise Buildings
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• v.7 no.4
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• pp.389-396
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• 2018

This paper presents a numerical investigation on the structural response of a multi-story building subjected to spreading multi-compartment fires. A recently proposed simple fire model has been used to simulate two spreading multi-compartment fire scenarios in a 10-story steel-framed office building. By assuming simple temperature rising and distribution profiles in the fire exposed structural components (steel beams, steel column and concrete slabs), finite element simulations using a three-dimensional structural model has been carried out to study the failure behavior of the whole structure in two multi-compartment fire conditions and also in a standard fire condition. The structure survived the standard fire but failed in the multi-compartment fire. Whilst more accurate fire models and heat transfer models are needed to better predict the behaviors of structures in realistic fires, the current study based on very simple models has demonstrated the importance and necessity of considering spreadingmulti-compartment fires in fire resistance design of multi-story buildings.

• Fire Science and Engineering
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• v.28 no.4
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• pp.29-34
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• 2014

In this study, to assess the validity of scaling law which was based on the ventilation factor and utilized in fields of compartment fires, numerical simulations were conducted on full- and 2/5 reduced-scale compartment fires using FDS and simulation results were compared with the previously published experimental data. The numerical modeling used in this study was verified by comparing the predicted temperature at several points of the upper layer with the experiment data. Temperature and concentration distribution inside of compartments and velocity profile at door of compartment are analyzed to assess the validity of scaling law. Comparison between the predicted results on the full- and reduced-scale compartments shows good agreements on the inner compartment flow patterns, outflowing flame patterns from the compartments, and vertical temperature distributions.

• Fire Science and Engineering
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• v.23 no.5
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• pp.103-109
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• 2009

In this study, fire simulations on the under-ventilated compartment fires have been conducted using the Fire Dynamics Simulator (FDS Ver. 5.2) and its prediction performance on the thermal and combustion chemical characteristics has been discussed. The temperature and chemical species concentrations in the upper layer of methane, heptane, and toluene fires located in a 2/5 scale compartment based on the ISO-9705 standard room are predicted and compared with the previously published experimental data. The results showed that the FDS simulations reproduced well the temperature of the ceiling and the mixture fraction in the upper layer under the well-ventilation conditions. For the under-ventilated fires, which were taken place due to the insufficient oxygen entrainment, the prediction by the FDS significantly under-estimated the production of carbon monoxide and soot compared to the experimental data.

• Nuclear Engineering and Technology
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• v.54 no.8
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• pp.2898-2914
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• 2022

When evaluating energy balance and temperature in reduced-scale fire experiments, which are conducted as an alternative to full-scale fire experiments, it is important to consider the similarity in the scale among these experiments. In this paper, a method considering the similarity of energy balance is proposed for setting the conditions for reduced-scale experiments of mechanically ventilated compartment fires. A small-scale fire experiment consisting of various cases with different compartment geometries (aspect ratios between 0.2 and 4.7) and heights of vents and fire sources was conducted under mechanical ventilation, and the energy balance in the quasi-steady state was evaluated. The results indicate the following: (1) although the compartment geometry varies the energy balance in a mechanically ventilated compartment, the variation in the energy balance can be evaluated irrespective of the compartment size and geometry by considering scaling factor F (∝h_effA_wR_T, where h_eff is the effective heat transfer coefficient, A_w is the total wall area, and R_T is the ratio of the spatial mean gas temperature to the exhaust temperature); (2) the value of R_T, which is a part of F, reflects the effects of the compartment geometry and corresponds to the distributions of the gas temperature and wall heat loss.

• International Journal of High-Rise Buildings
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• v.10 no.4
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• pp.345-364
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• 2021

Developments in the understanding of fire behaviour for large open-plan spaces typical of tall buildings have been greatly outpaced by the rate at which these buildings are being constructed and their characteristics changed. Numerous high-profile fire-induced failures have highlighted the inadequacy of existing tools and standards for fire engineering when applied to highly-optimised modern tall buildings. With the continued increase in height and complexity of tall buildings, the risk to the occupants from fire-induced structural collapse increases, thus understanding the performance of complex structural systems under fire exposure is imperative. Therefore, an accurate representation of the design fire for open-plan compartments is required for the purposes of design. This will allow for knowledge-driven, quantifiable factors of safety to be used in the design of highly optimised modern tall buildings. In this paper, we review the state-of-the-art experimental research on large open-plan compartment fires from the past three decades. We have assimilated results collected from 37 large-scale compartment fire experiments of the open-plan type conducted from 1993 to 2019, covering a range of compartment and fuel characteristics. Spatial and temporal distributions of the heat fluxes imposed on compartment ceilings are estimated from the data. The complexity of the compartment fire dynamics is highlighted by the large differences in the data collected, which currently complicates the development of engineering tools based on physical models. Despite the large variability, this analysis shows that the orders of magnitude of the thermal exposure are defined by the ratio of flame spread and burnout front velocities (V_S / V_BO), which enables the grouping of open-plan compartment fires into three distinct modes of fire spread. Each mode is found to exhibit a characteristic order of magnitude and temporal distribution of thermal exposure. The results show that the magnitude of the thermal exposure for each mode are not consistent with existing performance-based design models, nevertheless, our analysis offers a new pathway for defining thermal exposure from realistic fire scenarios in large open-plan compartments.

• Fire Science and Engineering
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• v.24 no.6
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• pp.145-152
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• 2010

A study on combustion efficiency concept was conducted for the under-ventilated fires in a fullscale ISO 9705 room. In particular, a comparison between global combustion efficiency (CE) measured outside the compartment and local CE measured at upper layer inside the compartment was focused. Heptane, toluene and iso-propanol were used to consider the wide ranges of heat of combustion and soot yield. As a result, the global CE was decreased linearly with increasing in global equivalence ratio (GER). On the other hand, the decreasing rate of local CE was increased gradually with increasing in GER. From these results, it was known that the information on local CE was very useful parameter to understand the fire phenomena inside the compartment. In addition, it was discussed that the local CE might be used as an important parameter in the process of scaling for the compartment fires.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 1997.11a
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• pp.66-76
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• 1997

In order to investigate the generation of carbon monoxide and heat loss of incomplete combustion in compartment fires, an experiment was conducted in a small scale compartment by using methanol as a fuel. The concentration of carbon monoxide and the toxicity parameter showed high values when the mass air - to - fuel stoichiometric ratio is under 1.0. The constitution of the combustion gas was showed to estimate it from the . The heat loss due to incompleteness of combustion is about one third of heat of combustion in case of under 1.0.

• Fire Science and Engineering
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• v.25 no.5
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• pp.93-99
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• 2011

In the present study, a numerical simulation was conducted to estimate the prediction performance of FDS on the carbon monoxide production in the under-ventilated compartment fires. Methane and heptane fires located in the a 2/5 scale compartment based on the ISO-9705 standard room was simulated using FDS Ver. 5.5. Through the comparison between the computed results and the earlier published experimental data, the performance of FDS was estimated on the predictions of the combustion gases concentration in the hot upper layer of the compartment and the effects of CO yield rate on the estimation of CO production at local points were analyzed. From the results, it was known that FDS Ver. 5.5, in which the two-step reaction mixture fraction model implemented, was more effective on the prediction of CO concentration compared to the previous FDS version. In addition, controlling CO yield rate made the predicted CO concentration get closer to the experimental data for the fires of the under-ventilated condition.

• Journal of ILASS-Korea
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• v.13 no.3
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• pp.156-161
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• 2008

The present article reports a numerical study on the fire characteristic change by water-mist in under-ventilated compartments. The natural gas and heptane pool fires are used as fire sources, which are located in the bottom center of the 2/5 reduced-scaled model of the ISO 9705 standard room. The fire modeling using the FDS (Fire Dynamics Simulator) is validated by comparison with previously published experimental results. For temperature and combustion gas concentrations at two positions located in the upper layer of compartment, the predicted results with and without water-mist are compared each other. The results show that under the water-mist operation, the predicted temperature and carbon monoxide concentration reduce as $300{\sim}400^{\circ}C$ and about 20%, respectively, compared to those without water-mist.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2009.04a
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• pp.423-430
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• 2009

본 논문에서는 ISO-9705 공간의 2/5 스케일 축소모형에 대한 화재 실험에서 측정된 고온 상층부의 연소가스 농도를 혼합분율 개념을 도입하여 분석함으로써 환기부족 상태의 실내화재에서 발생되는 연소생성물의 특성을 파악하고자 한다. 화재실 내부 고온 상층부의 두 지점에서 측정된 잔존 탄화수소, 일산화탄소, 이산화탄소, 산소, 수트(soot) 등의 성분비를 혼합분율의 함수로 내어 분석하였다. 또한 탄화수소 연료의 이상적인 반응에 근거한 상태 관계식과 비교함으로써 환기부족 화재에서 혼합분율 모델의 적용성을 분석하였다. 혼합분율 분석을 이용함으로써 측정된 수많은 데이터들을 화재 크기나 측정 위치에 상관없이 하나의 파라미터에 대해서 정리하여 전체적으로 분석할 수 있었다. 또한 혼합분율 분석에서 수트를 고려하는 것이 분석의 정확성을 크게 향상시킴을 확인할 수 있었다.