• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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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.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2005.11a
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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.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2006.04a
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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.

• Journal of Korean Association for Spatial Structures
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• v.16 no.1
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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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• v.5 no.4
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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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• v.55 no.6
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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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• v.32 no.7
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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.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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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.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.05a
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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.

• Fire Science and Engineering
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• v.25 no.1
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• pp.42-49
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• 2011

In the high temperature situation like in a fire, the high strength of concrete (HSC) has extreme danger named explosive spalling. It is assumed that the major cause of explosive spalling is water vapour pressure inside concrete. This paper examines the effect of the compressive strength and the moisture content on the initial occurrence of explosive spalling. For the effective experiment of the initial explosive spalling, the curve of ISO834 temperature profile is applied on the basis of 15 minute and 30 minute. As a result, the more increase the compressive strength and the moisture content, the more increase the occurrence and phenomenon of explosive spalling. This paper analyzes the territory of explosive spalling depending the compressive strength and the moisture content. The explosive spalling is not examined in the case of the compressive strength 50~100 MPa and the moisture content below 3% and the compressive strength over 100 MPa and the moisture content below 1%. Also, due to the HSC, which makes it more difficult to transport vapour and moisture, very high vapour-pressure may occur close to the surface, there is a greater risk that HSC spalls compared with normal strength concrete (NSC).