• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.421-424
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• 2006

This study, in order for perceiving the mechanical attribute followed by the explosive spalling of high strength concrete material under high temperature and evaluating capacity of endurance of material, targets understanding capacity of endurance of material such as explosive spalling in high temperature, temperature by thickness of clothing, transformation extent, transformation speed and displacement, stocking the maximum load based on the Allowable Stress Design Method. As a result of experimenting the explosive spalling attribute of high strength concrete material, the one possibly causing serious damage is the 50 MPa concrete. In all aspects of 60 MPa concrete, explosive spalling happens. Especially, it is hazardous enough to reveal all the iron bar. All explosive spalling is intensively concentrated on the surface of concrete for the first $5{\sim}25$ minutes, which urges for the explosive spalling protection action. As a result of evaluating the structural safety by the transformation of high strength concrete, while beam assures the fire safety meeting regulation, 60 MPa shows the dramatic increase of transformation, which only counts 84% of safety. In a column, both the concrete exclusion and excessive explosive spalling are concentrated upper part of column, which brings about the dramatic transformation, so it only meets the 50% of safety regulation. Likewise, in 80, 100 MPa concrete which was never experimented considering the condition of domestic structural endurance stocking devices, the faster collapse is expected.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 2005년도 공동추계학술논문발표회 논문집
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• pp.81-85
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• 2005

Recently, fire resistance of high performance concrete for explosive spalling was issued as high performance concrete was vulnerable to the explosive spalling in initial fire. Therefore, in this study, an experiment about reduction effect to explosive spalling of high performance concrete is performed by adding several polymer fiber with various volume fraction, an then final fiber and volume fraction of that which reduce the explosive spalling of high performance concrete is presented. As the result of this study, the most fitted fiber volume fraction of reducing effect for explosive spalling at high performance concrete is under the 0.1%, as consider the flowability and efficiency.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 2006년도 춘계학술논문발표회 논문집
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• pp.172-175
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• 2006

Recently, fire resistance of high performance concrete for explosive spatting was issued as high performance concrete was vulnerable to the explosive spatting in initial fire. Therefore, This study is willing to propose fundamental data for quick and accurate diagnosis of deteriorated concrete structure by fire damage with making variable concrete test specimen, exposing high temperature environment, observing the explosive spatting and examining engineering property.

• 한국공간구조학회논문집
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• 제16권1호
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• pp.105-113
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• 2016

Since the 1980s, the number of large space buildings in Korea has consistently been increasing due to large scale international competitions such as the Olympics and the World Cup, demands for environmental improvement, and development of structural systems. Due to these reasons, this paper conducted a comparative analysis on terrorism risk factors of large space structure and skyscrapers in Korea. The results suggest that the total risk level of high-rise and large space structure was "medium level risk" and that the terrorism risk level for large space structure was as high as that for high-rise buildings. As it relates to the risk levels depending on scenarios, terrorism risks to large space structure were higher than high-rise buildings in the "internal explosion" and "internal intrusion" categories. And the results of analyzing explosion-related scenarios except for CBR suggest that terrorism risks to large space structure were highest when it comes to Internal-Explosive followed by Internal-Intrusion and Explosive-Zone I; and the results showed a regular pattern. On the other hand, in the case of high-rise buildings, terrorism risks were highest in Internal-Explosive followed by Explosive-Zone I and Explosive-Zone II; and the results showed an irregular pattern.

• Computers and Concrete
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• 제5권4호
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• pp.279-293
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• 2008

In the present paper a 3D thermo-hygro-mechanical model for concrete is used to study explosive spalling of concrete cover at high temperature. For a given boundary conditions the distribution of moisture, pore pressure, temperature, stresses and strains are calculated by employing a three-dimensional transient finite element analysis. The used thermo-hygro-mechanical model accounts for the interaction between hygral and thermal properties of concrete. Moreover, these properties are coupled with the mechanical properties of concrete, i.e., it is assumed that the mechanical properties (damage) have an effect on distribution of moisture (pore pressure) and temperature. Stresses in concrete are calculated by employing temperature dependent microplane model. To study explosive spalling of concrete cover, a 3D finite element analysis of a concrete slab, which was locally exposed to high temperature, is performed. It is shown that relatively high pore pressure in concrete can cause explosive spalling. The numerical results indicate that the governing parameter that controls spalling is permeability of concrete. It is also shown that possible buckling of a concrete layer in the spalling zone increases the risk for explosive spalling.

• Nuclear Engineering and Technology
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• 제55권6호
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• pp.1988-1993
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• 2023

This experimental study investigated the effect of silica fume mixed in concrete blocks on laser-induced explosion behavior. We used a 5.3 kW fiber laser as a thermal source to induce explosive spalling on a concrete surface blended with and without silica fume. An analytical approach based on the difference in the removal rate and thermal behavior was used to determine the effect of silica fume on laser-induced explosive spalling. A scanner was employed to calculate the laser-scabbled volume of the concrete surface to derive the removal rate. The removal rate of the concrete mixed with silica fume was higher than that of without silica fume. Thermal images acquired during scabbling were used to qualitatively analyze the thermal response of laser-induced explosive spalling on the concrete surface. At the early stage of laser heating, an uneven spatial distribution of surface temperature appeared on the concrete blended with silica fume because of frequent explosive spalling within a small area. By contrast, the spalling frequency was relatively lower in laser-heated concrete without silica fume. Furthermore, we observed that a larger area was removed via a single explosive spalling event owing to its high porosity.

• Bulletin of the Korean Chemical Society
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• 제32권7호
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• pp.2319-2324
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• 2011

Molecular structures and chemical properties of 1-aminoimidazole derivatives have been investigated at high levels of density functional theories. Heat of formation, density, explosive performances and impact sensitivities have been estimated at the global minimum of potential energy surface. As more nitro groups are introduced, the explosive performances of 1-aminoimidazole derivatives are enhanced, while the impact sensitivity becomes more sensitive. A two-dimensional plot between explosive performance and impact sensitivity has been utilized to comprehend the technical status of new explosive candidates. Based on locations in the two-dimensional plot, 1-aminodinitroimidzole isomers appears to have a potential to be good candidates for insensitive explosives, and 1-aminotrinitroimidazole may become a powerful explosive molecule whose behavior is quite close to HMX.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
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• pp.521-524
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• 2005

This study is an experiment for reducing effect of explosive spalling by fiber addition ratio and kinds of fiber at high performance concrete. So, high strength concrete were made addition to PVA and PP fiber as diameter of 34, 100 $\mu$m and 40 $\mu$m by fiber addition ratio as 0.05, 0.1, 0.3$\%$. After those were heated respectively for 30 in accordance with Standard Time-Temperature Curve. And then conditions of explosive spalling were divided into four grades, and characters of explosive spalling were investigated.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 춘계 학술논문 발표대회
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• pp.323-325
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• 2013

This study on the proposes a spalling mechanism based on the results of a fire resistance test of HSC(High Strength Concrete) considering important factors of spalling occurrence. The factors considered in this two-sided are fire resistance test to ISO 834 fire curve. In this study, explosive spalling phenomena in the specimens were investigation.

• 한국화재소방학회논문지
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• 제25권1호
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• pp.42-49
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• 2011

화재와 같은 고온 환경에서 고강도화 된 콘크리트는 폭렬(Explosive Spalling)이 발생할 가능성이 있으며, 이러한 폭렬의 원인으로는 콘크리트 내부의 수증기압이 가장 큰 원인으로 제기되고 있다. 본 논문은 콘크리트의 압축강도 및 함수율이 초기 폭렬특성에 미치는 영향을 실험적으로 규명하는 것을 목적으로 하였다. 실험변수는 양생방법, 압축강도, 함수율로 설정하였으며, KS F 2257 화재온도이력곡선을 15분, 30분 적용하여 콘크리트의 초기 폭렬특성을 실험적으로 검토하였다. 그 결과 압축강도 함수율이 증가할수록 폭렬발생이 증대되는 경향이 나타났으며, 초기 15분 이내에서 대부분의 폭렬이 발생하는 것으로 나타났다. 또한 압축강도 및 함수율에 따른 폭렬발생영역을 분석하였으며, 압축강도 50~100MPa의 경우 함수율 3% 이하, 100MPa 이상의 경우는 1% 이하로 제어할 경우 폭렬현상이 발생하지 않을 것으로 판단되었다. 공극구조에 대한 분석 결과 고강도화 될수록 공극이 세공화됨으로써 탈수현상이 지연되었으며, 이러한 원인으로 인한 수분의 위상변화에 따른 폭렬압 증가는 고강도콘크리트의 심각한 폭렬에 대한 원인중 하나가 될 것으로 판단되었다.