• Explosives and Blasting
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• v.33 no.3
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• pp.1-13
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• 2015

Accidents related to gas explosion are frequently happened in foreign countries and in Korea. For the evaluation and the analysis of gas explosions, TNT equivalent methods are used. In this study, the influence of the selection of chemical equation in TNT explosion and the selection of enthalpy of the products on the explosion energy, detonation pressure, velocity of detonation, and temperature was calculated. Depending on the chemical equations, the maximum detonation pressure can be 2 times higher than the minimum. As an example for applying TNT equivalent method, an explosion of methane gas in a confined volume was assumed. With the TNT equivalent, it was possible to predict the variation of peak overpressure and impulse with the distance from the explosion location.

• Explosives and Blasting
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• v.36 no.4
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• pp.26-34
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• 2018

Explosions of vapor cloud formed due to the leakage from installations with flammable fuels have often occurred in Korea and foreign countries. In this study, TNT equivalency method and Multi-Energy method for vapor cloud explosion blast modelling are described and demonstrated in a case study. As TNT equivalency method is simple and direct, it has been widely used for modelling a vapor cloud explosion blast. But TNT equivalency method found to be difficult to select a proper correlation between the amount of combustion energy produced from the vapor cloud explosion and the equivalent amount of TNT to model its blast effects. Multi-Energy method assumes that the strength of vapor cloud explosion blast depends on the layout of the space where the vapor cloud is spreading. Strictly speaking, the explosive potential of a vapor cloud is dependent upon the density of the obstructed regions. In this study, Flixborough accident are analyzed as a case study to assess the applicability of TNT equivalency method and Multi-Energy method. TNT equivalency method and Multi-Energy method found to be applicable if coefficient of TNT equivalency and coefficient of strength of explosion blast are selected properly.

• Explosives and Blasting
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• v.38 no.1
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• pp.1-13
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• 2020

Gas explosion accidents are steadily being issued due to increased gas consumption in Korea and foreign countries. To analyze the effects of these gas explosions, a TNT equivalent method is used. In this study, the TNT equivalent was calculated in the event of an explosion due to the volume content in the air of CO, CH₄ and C₂H₄, the typical flammable gases emitted by coal. Also, the peak overpressure and impulse variation with the distance from explosion point were compared and analyzed by gas using the calculated equivalent value of TNT. The upper limit of the TNT equivalent for the three mixed gases is up to five times larger than the other gases mixture. In addition, the peak overpressure and impulse, which are factors of the TNT characteristic curve, are also increasing as the number of gases increases.

• Explosives and Blasting
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• v.34 no.1
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• pp.1-10
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• 2016

On August 12, 2015, two huge explosions were accidently happened in Tianjin port, China. The explosion energies of the two explosions were similar to those of TNT 3 tons and TNT 21 tons. Until now, the cause of the explosions was not clearly announced but some guesses of the cause were released. One of the possible cause of the explosion is the generation of explosive acetylene gas from the chemical reaction between $CaC_2$ and spraying water to extinguish fire happened at the storage site of different chemical compounds. The explosion of acetylene gas might ignite the explosion of 800 tons of ammonium nitrate. In this study, the explosion due to the scenario was analyzed in order to check that such a chemical reaction can produce the huge explosion observed at the Tianjin accident.

• Explosives and Blasting
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• v.41 no.3
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• pp.73-92
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• 2023

With the increase of risk of gas explosion, various methods for indirectly estimating the explosion paramaters, which are required for the prediction of gas explosion scale and impact. In this study, the characteristics of the most frequently used methods such as TNT equivalent method, TNO multi-energy method, and BST method and the processes for determining the parameters of the methods were compared. In the case of TNT equivalent method, an adequate selection of the efficiency factor for various conditions such as the type of vapor cloud explosion and explosion material is needed. There is no objective guidelines for the selection of class number in TNO multi-energy method and it is not possible to estimate negative overpressure. It was found that there were some mistakes in the reported parameter values and suggested corrected values. BST method provides more detailed guidelines for the estimation of the explosion parameters including negative overpressure, but the graphs used in this methods are not clear. In order to overcome the problem, the graphs were redrawn. A more convenient estimation of explosion parameters with the numerical expression of the redrawn graphs will be available in the future.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.1
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• pp.1-8
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• 2021

Vapor cloud explosions show different characteristics from that caused by ordinary TNT explosives and their loading effect is similar to pressure waves. Typical methods used for blast pressure calculations are the TNT-equivalent method and multi-energy method. The TNT-equivalent method is based on shock waves, similar to a detonation phenomenon, and multi-energy method is based on pressure waves, similar to a deflagration phenomenon. This study was conducted to derive an appropriate blast pressure by applying various plant explosion cases. SDOF analysis and nonlinear dynamic analysis were performed to compare the degree of deformation and damage of the selected structural members for the explosion cases. The results indicated that the multi-energy method was more exact than the TNT-equivalent method in predicting the blast pressure of vapor cloud explosions. The blast pressure of vapor cloud explosion in plants can be more accurately calculated by assuming the charge strength of multi-energy method as 7 or 8.

• Computers and Concrete
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• v.31 no.6
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• pp.561-570
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• 2023

In this paper, the structural performance of RC and HPFRCC slabs exposed to a TNT explosion were numerically investigated. A finite element model was established using the MM-ALE method in the LS-DYNA program to simulate a near-ground TNT explosion at a scaled distance of 1.08 m/kg³. The K&C model was calibrated to exactly reflect the material properties of HPFRCCs that were developed in KICT and KNU. Numerical and experimental results were compared for the damage distribution and failure shape of the slabs. Based on the verified numerical model, a parametric study was carried out to demonstrate the effects of compressive strength and thickness of the slab on the blast resistance. In particular, the spallation failure on the back side of the slab is greatly dependent on the thickness. Finally, additional numerical simulations were conducted to explore the variation in blast pressure characteristics according to the scaled distance and explosive shape. It was confirmed that the pressure induced by cubic TNT was more destructive to the slab than cylindrical and spherical TNT in a nearfield explosion.

• Journal of the Korean Society of Safety
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• v.30 no.4
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• pp.56-63
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• 2015

Gas explosion accidents could cause a catastrophe. we need specialized and systematic accident investigation techniques to shed light on the cause and prevent similar accidents. In this study, we had performed LNG explosion simulation using AUTODYN which is the commercial explosion program and predicted the damage characteristics of the structures by LNG explosive power. In the first step, we could get LNG's physical and chemical explosion properties by calculation using TNT equivalency method. And then, by applying TNT equivalency value about the explosion limit concentration of LNG on the 2D-AUTODYN simulation, we could get the explosion pressure wave profiles (explosion pressure, explosion velocity, etc.). In the last step, we performed LNG explosion simulation by applying to the explosion pressure wave profiles as the input data on the 3D-AUTODYN simulation. As a result, we had performed analyzing of the explosion characteristics of LNG in accordance with concentration through the 3D-AUTODYN simulation in terms of the explosion pressure behavior and structure's destruction and damage behavior.

• Explosives and Blasting
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• v.40 no.3
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• pp.44-53
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• 2022

This study evaluates the applicability of the TNT Equivalency Method, Multi-Energy Method, and Baker-Strehlow-Tang (BST) Method, which are blast prediction models used to determine the overpressure of blast wave generated from vapor cloud explosion. It is assumed that the propane leaked from a propane storage container with a capacity of 2000 kg installed in an area where studio houses and shopping centers are concentrated causes a vapor cloud explosion. The equivalent mass of TNT calculated by applying the TNT Equivalency Method is found to be 4061 kg. Change of overpressure with the distance obtained by the TNT Equivalency Method, Multi-Energy Method, and BST Method is rapid and the magnitude of overpressure obtained by the TNT Equivalency Method and BST method is generally similar within 100 m from explosion center. As a result of comparing the overpressure observed in the actual vapor cloud explosion case with the overpressure obtained by applying the TNT Equivalent Method, Multi-Energy Method, and BST Method, the BST Method is found to be the best fit. As a result of comparing the overpressure with the distance obtained by each explosion prediction model with the damage criteria for structure, it is estimated that the structure located within 90 m from explosion center would suffer a damage more than partial destruction, and glass panes of the structure separated by 600 m would be fractured.

• Journal of the Korean Institute of Gas
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• v.26 no.5
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• pp.58-65
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• 2022

Gas explosion accidents could cause a catastrophe. we need specialized and systematic accident investigation techniques to shed light on the cause and prevent similar accidents. In this study, we had performed LPG explosion simulation using AUTODYN which is the commercial explosion program and predicted the damage characteristics of the structures by LNG explosive power. In the first step, we could get LPG's physical and chemical explosion properties by calculation using TNT equivalency method. And then, by applying TNT equivalency value about the explosion limit concentration of LPG on the 2D-AUTODYN simulation, we could get the explosion pressure wave profiles (explosion pressure, explosion velocity, etc.). In the last step, we performed LPG explosion simulation by applying to the explosion pressure wave profiles as the input data on the 3D-AUTODYN simulation. As a result, we had performed analyzing of the explosion characteristics of LPG in accordance with concentration through the 3D-AUTODYN simulation in terms of the explosion pressure behavior and structure destruction and damage behavior. The analyses showed that the generated stresses of the structures were lower than the compressive strengths in cases 1(two lane) and 2(four lane), while the generated stress in case 3(six lane) was 8.68e3 kPa, which exceeded the compressive strength of 5.89e3 kPa.