• 대한조선학회논문집
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• 제51권5호
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• pp.380-387
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• 2014

Piper Alpha disaster drew attention to the damage likely to arise from explosions and fires on an offshore platform. And great concerns have been increased to prevent these hazards. Blast wall is one of the passive safety systems; it plays a key part of minimizing the consequences. However, a buckling due to explosion loads is a factor which can reduce the strength of blast wall. The buckling often occurs between web and flange at the center of blast wall. This study aims to find a solution for reinforcing its strength by installing a flat plate at the spot where the buckling occurs. First of all, ANSYS finite element method is adopted to numerically compute the structural resistance characteristic of blast wall by using a quasi-static approach. Sequentially, the impact response characteristics of blast wall are investigated the effect on thickness of flat plate by using ANSYS/LS-DYNA. Finally, pressure-impulse diagrams (P-I diagram) are presented to permit easy assessment of structural response characteristics of stiffened blast wall. In this study, effective use is made to increase structural intensity. of blast wall and acquired important insights have been documented.

• 한국구조물진단유지관리공학회 논문집
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• 제26권5호
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• pp.151-160
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• 2022

최근 폭발사고의 빈도수가 증가함에 따라 주요 구조부재의 손상을 저감시킬 수 있는 방호 구조물 설계에 대한 관심이 높아지고 있다. 그러나, 방호 구조물의 방호성능에 대한 국내 연구는 아직 미진한 실정이며, 아직 설계 가이드라인도 충분히 갖추어지지 못한 실정이다. 따라서, 본 연구에서는 FRP 시트 보강유무를 변수로 하여 RC 방호벽에 대한 해석적 연구를 수행하였다. 해석은 LS-DYNA 프로그램을 활용하여 수행되었으며, 해석을 통해 RC 방호벽과 FRP 시트로 보강된 RC 방호벽의 변위-시간이력곡선, 압력-충격량 도표, 취약도 곡선을 도출하였다. FRP 시트 보강방법은 RC 방호벽의 방호성능을 향상시키는데 매우 효율적인 것으로 나타났다. 또한, 폭발하중의 크기가 클수록 RC 방호벽에 대한 FRP 시트의 보강효과는 높아지는 것으로 나타났다.

• 한국안전학회지
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• 제38권6호
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• pp.9-15
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• 2023

Hydrogen is gaining attention as a sustainable and renewable energy source, potentially replacing fossil fuels. Its high diffusivity, wide flammable range, and low ignition energy make it prone to ignition even with minimal friction, potentially leading to fire and explosion risks. Workplaces manage ignition risks by classifying areas with explosive atmospheres. However, the effective installation of a blast wall can significantly limit the spread of hydrogen, thereby enhancing workplace safety. To optimize the wall installation of this barrier, we employed the response surface methodology (RSM), considering variables such as wall distance, height, and width. We performed 17 simulations using the Box-Behnken design, conducted using FLACS software. This process yielded two objective functions: explosion likelihood near the barrier and explosion overpressure affecting the blast wall. We successfully achieved the optimal solution using multi-objective optimization for these two functions. We validated the optimal solution through verification simulations to ensure reliability, maintaining a margin of error of 5%. We anticipated that this method would efficiently determine the most effective installation of a blast wall while enhancing workplace safety.

• 산업기술연구
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• 제20권A호
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• pp.257-267
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• 2000

It was difficult to apply conventional excavation methods in some sections from Seoul to Pusan high speed rail road construction of 1 lot 2, due to highway concrete road, gas pipe, water pipe and nearby factories with automatic control system machine. To excavate safely and efficiently in these sections new blast patterns were employed within allowable blast vibration level, by test blast and controlled vibration by sequential blast. Behaviors of the rock mass including convergence and displacement around tunnel were measured with construction works and the crack width in concrete wall was also monitored for controlling allowable limits. The results can be summarized as follow : 1. The allowable blast vibration level in structure site is less 1.0cm/sec for highway concrete, 0.5 cm/sec for gas pipe, water pipe and building housing and 0.3 cm/sec for automatic control system machine. 2. The convergence displacement, single rod extensometer and multi rod extensometer around tunnel and cracks in concrete wall were measured, it was confirmed that the measured values were converged within allowable level. 3. The empirical formular of ground vibrations with 90% confidence lines for PD-3 was given as follow. $$V_{90%}=45.549({\frac{D}{\sqrt{W}}})^{-1.353}$$

• Computers and Concrete
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• 제17권2호
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• pp.215-225
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• 2016

High performance materials such as Fiber Reinforced Plastic (FRP) are often used for retrofitting structures against blast loads due to its ductility and strength. The effectiveness of retrofit materials needs to be precisely evaluated for the retrofitting design based on the dynamic material responses under blast loads. In this study, the blast resistance of Carbon Fiber Reinforced Plastic (CFRP) and Kevlar/Glass hybrid fabric (K/G) retrofitted reinforced concrete (RC) wall is analyzed by using the explicit analysis code LS-DYNA, which accommodates the high-strain rate dependent material models. Also, the retrofit effectiveness of FRP fabrics is evaluated by comparing the analysis results for non-retrofitted and retrofitted walls. The verification of the analysis is performed through comparisons with the previous experimental results.

• Smart Structures and Systems
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• 제21권5호
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• pp.561-569
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• 2018

Ground vibration is one of the most undesirable effects induced by blast operation in mountain tunnels, which could cause negative impacts on the residents living nearby and adjacent structures. The ground vibration effects can be well represented by peak particle velocity (PPV) and corner frequency ($f_c$) on the ground. In this research, the PPV and the corner frequency of the mountain surface above the large-span tunnel of the new Badaling tunnel are observed by using the microseismic monitoring technique. A total of 53 sets of monitoring results caused by the blast inside tunnel are recorded. It is found that the measured values of PPV are lower than the allowable value. The measured values of corner frequency are greater than the natural frequencies of the Great Wall, which will not produce resonant vibration of the Great Wall. The vibration effects of associated parameters on the PPV and corner frequency which include blast charge, rock mass condition, and distance from the blast point to mountain surface, are studied by regression analysis. Empirical formulas are proposed to predict the PPV and the corner frequency of the Great Wall and surface structures due to blast, which can be used to determine the suitable blast charge inside the tunnel.

• 한국전산구조공학회논문집
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• 제27권4호
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• pp.281-288
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• 2014

가스폭발은 해양플랜트 산업에서 발생할 수 있는 치명적인 사고 중 하나이며, 탑사이드 플랫폼은 폭발압력에 따른 구조 건전성을 확보해야만 한다. 따라서, 해양플랜트 분야에서는 이러한 폭발사고에 대비한 방폭설계에 관한 많은 연구가 수행되었지만, 여전히 추가적으로 세밀한 분석이 더 필요한 실정이다. 폭발 설계하중 계산과정에서 도출된 충격량은 CFD 해석결과로 계측된 폭발 압력 응답에서의 곡선 아래 면적의 절대 값에 의해 결정되어 진다. 하지만 가스폭발에서의 부압구간은 TNT 폭발이나 가스폭발과는 달리 상당부분 존재한다. 본 연구의 목표는 이러한 부압구간이 구조물의 거동에 미치는 영향에 대해서 분석하는 것이다. 따라서 방폭설계가 필수적으로 요구되어지는 FPSO 탑사이드의 방화벽을 폭발하중에 따른 구조 응답을 분석하기 위한 대상물로 선정하였다. 폭발 하중-시간이력 데이터는 FLACS를 이용한 폭발 시뮬레이션 과정을 통해 획득하였으며, LS-DYNA는 비선형 과도 응답해석을 위해 사용되었다.

• Computers and Concrete
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• 제17권2호
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• pp.201-214
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• 2016

The outer tank of a liquefied natural gas (LNG) storage tank is a longitudinally and meridianally pre-stressed concrete (PSC) wall structure. Because of the current trend of constructing larger LNG storage tanks, the pre-stressing forces required to increase wall strength must be significantly increased. Because of the increase in tank sizes and pre-stressing forces, an extreme loading scenario such as a bomb blast or an airplane crash needs to be investigated. Therefore, in this study, the blast resistance performance of LNG storage tanks was analyzed by conducting a blast simulation to investigate the safety of larger LNG storage tanks. Test data validation for a blast simulation of reinforced concrete panels was performed using a specific FEM code, LS-DYNA, prior to a full-scale blast simulation of the outer tank of a 270,000-kL LNG storage tank. Another objective of this study was to evaluate the safety and serviceability of an LNG storage tank with respect to varying amounts of explosive charge. The results of this study can be used as basic data for the design and safety evaluation of PSC LNG storage tanks.

• Structural Engineering and Mechanics
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• 제84권5호
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• pp.675-684
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• 2022

The conventional single-degree-of-freedom (SDOF) system is appropriate for dynamic response analysis of paneltype structures without an opening. However, the typical building structures usually have four-sided fixed walls having an opening. Therefore, it may induce a considerable error when dynamic responses are estimated based on the conventional SDOF system, since the SDOF system cannot consider the effect of an opening during the SDOF analysis. For this reason, this study proposes a new SDOF system to consider the effect of an opening by adjusting its load-mass factor. The load-mass factor can be modified based on the assumption that the behaviors of the four-sided fixed wall with an opening is very similar to the behaviors of the same size wall without an opening, when the uniformly distributed blast loaded area is identical. In order to confirm a feasibility of the proposed SDOF system, a series of numerical simulations were carried out for the four-sided fixed reinforced concrete (RC) wall under a blast load. The dynamic responses estimated from the proposed SDOF system and the conventional SDOF system were compared with the dynamic responses evaluated from the finite element (FE) analysis. Especially, for the maximum dynamic responses except for 50% opening case, the proposed SDOF system had about 1.1% to 25.7% normalized errors while the conventional SDOF system had about 4.1% to 49.1% normalized errors.

• Structural Engineering and Mechanics
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• 제32권2호
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• pp.213-233
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• 2009

In this paper the study of a reinforced concrete wall used as protection against accidental explosions in the petrochemical industry is presented. Many alternatives of accidental scenarios and sizes of the wall are analyzed and discussed. Two main types of events are considered, both related to vessel bursts: Pressure vessel bursts and BLEVE. The liberated energy from the explosion was calculated following procedures firmly established in the practice and the effects over the structures and the reinforced concrete wall were calculated by using a CFD tool. The results obtained show that the designed wall reduces the values of the peak overpressure and impulse and, as a result, the damage levels to be expected. It was also proved that a reinforced concrete wall can withstand the blast load for the considered events and levels of pressure and impulse, with minor damage and protect the buildings.