• Title/Summary/Keyword: 폭발손상평가

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Experimental Evaluation of Bi-directionally Unbonded Prestressed Concrete Panel Impact-Resistance Behavior under Impact Loading (충돌하중을 받는 이방향 비부착 프리스트레스트 콘크리트 패널부재의 충돌저항성능에 대한 실험적 거동 평가)

  • Yi, Na-Hyun;Lee, Sang-Won;Lee, Seung-Jae;Kim, Jang-Ho Jay
    • Journal of the Korea Concrete Institute
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    • v.25 no.5
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    • pp.485-496
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    • 2013
  • In recent years, frequent terror or military attacks by explosion or impact accidents have occurred. Examplary case of these attacks were World Trade Center collapse and US Department of Defense Pentagon attack on Sept. 11 of 2001. These attacks of the civil infrastructure have induced numerous casualties and property damage, which raised public concerns and anxiety of potential terrorist attacks. However, a existing design procedure for civil infrastructures do not consider a protective design for extreme loading scenario. Also, the extreme loading researches of prestressed concrete (PSC) member, which widely used for nuclear containment vessel, gas tank, bridges, and tunnel, are insufficient due to experimental limitations of loading characteristics. To protect concrete structures against extreme loading such as explosion and impact with high strain rate, understanding of the effect, characteristic, and propagation mechanism of extreme loadings on structures is needed. Therefore, in this paper, to evaluate the impact resistance capacity and its protective performance of bi-directional unbonded prestressed concrete member, impact tests were carried out on $1400mm{\times}1000mm{\times}300mm$ for reinforced concrete (RC), prestressed concrete without rebar (PS), prestressed concrete with rebar (PSR, general PSC) specimens. According to test site conditions, impact tests were performed with 14 kN impactor with drop height of 10 m, 5 m, 4 m for preliminary tests and 3.5 m for main tests. Also, in this study, the procedure, layout, and measurement system of impact tests were established. The impact resistance capacity was measured using crack patterns, damage rates, measuring value such as displacement, acceleration, and residual structural strength. The results can be used as basic research references for related research areas, which include protective design and impact numerical simulation under impact loading.

An Examination on the Dispersion Characteristics of Boil-off Gas in Vent Mast Exit of Membrane Type LNG Carriers (멤브레인형 LNG선박 화물탱크 벤트 마스트 출구에서의 BOG 확산 특성에 관한 연구)

  • Kang, Ho-Keun
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.19 no.2
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    • pp.225-231
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    • 2013
  • Liquefied gas carriers generally transport cargoes of flammable or toxic nature. Since these cargoes may cause an explosion, fire or human casualty, the accommodation spaces, service spaces and control stations of liquefied gas carriers should be so located as to avoid ingress of gas. For this reason, the paragraph 8.2.9 of IGC Code in IMO requires that the height of vent exits should be not less than B/3 or 6 m whichever is greater, above the weather deck and 6 m above the working area and the fore and aft gangway to prevent any concentration of cargo vapor or gas at such spaces. Besides as known, the LNG market has been growing continually, which has led to LNG carriers becoming larger in size. Under this trend, the height of a vent will have to be raised considerably since the height of a vent pipe is generally decided by a breadth of a corresponding vessel. Accordingly, we have initiated an examination to find an alternative method which can be used to determine the safe height of vent masts, instead of the current rule requirement. This paper describes the dispersion characteristics of boil-off gas spouted from a vent mast under cargo tank cool-down conditions in the membrane type LNG carriers.