• Title/Summary/Keyword: LNG storage tanks

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A Study on the Fracture Behavior of a Crack in 9% Ni Steel Considering Constraint Effect (구속효과를 고려한 9% Ni강 균열의 파괴거동 해석에 관한 연구)

  • Kim, Young Kyun;Yoon, Ihn soo;Kim, Jae Hoon
    • Journal of the Korean Institute of Gas
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    • v.25 no.6
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    • pp.14-21
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    • 2021
  • Inner shell material of LNG storage tanks that store ultra-low temperature LNG at -162℃ requires structural integrity assessment of a crack-like defect. From the viewpoint of conventional fracture mechanics, the assessment has mainly performed by single parameter using stress intensity factor K, J-integral and CTOD. However, the stresses in a material of crack tip are not unique caused by constraint loss due to size and geometry of the structure. Various attempts have been made to complement a single parameter fracture mechanics, typically with Q-stress. In this paper, we have performed a two-parameter approach by deriving the Q-stress coupling with J-integral suitable for the evaluation of the crack tip stress field in the non-linear elastic region. A quantitative evaluation of the constraint effect has performed by using the J-Q approach. It was evaluated that the SENB type specimen had a crack ratio of 0.1 to 0.7 and the wide type specimen had a crack ratio of 0.2 to 0.6.

Application of Seismic Isolation and Vibration Control in Korea (우리나라의 면진 및 진동제어)

  • Lee, Dong-Guen;Kim, Tae-Ho
    • Journal of the Earthquake Engineering Society of Korea
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    • v.10 no.6 s.52
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    • pp.67-77
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    • 2006
  • Seismic activity of Korea is not so high as that of Japan or California and most of the structures were designed without considering the influence of earthquakes until the first seismic design code was enforced in 1988. Therefore, it was very hard to find seismically isolated structures in Korea until 1980's. Korean engineers assumed that the seismic isolation or vibration control would be useful only in a high seismicity region while such technologies can be quite useful in a low seismicity region for the efficient reduction of earthquake damages. Recently, Korean engineers began to have interest in the seismic isolation or vibration control and applied it to some important structures such as LNG storage tanks, many bridges and several buildings. However, design codes are not defining such useful advanced technologies for the design of building structures and several projects employing seismic isolation or vibration control in the design of structures had difficulties in obtaining construction permit from the local government. Therefore, it is an urgent requirement to introduce these advanced technologies in the seismic design code.

Review on the Effects of Material Heterogeneity on Fracture Toughness in Steel Weldment (재질적 불균질이 강용접부의 파괴인성에 미치는 영향에 관한 고찰)

  • Jang J.-i.;Yang Y.-c.;Kim W.-s.;Lee B.-W.;Kwon D.
    • Journal of the Korean Institute of Gas
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    • v.3 no.2 s.7
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    • pp.1-10
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    • 1999
  • The evaluation of fracture toughness in weldment is necessary for the safety performance of industrial structures with large scale such as various power plants, LNG (liquefied natural gas) storage tanks, etc. It is generally known that weldments have material heterogeneity, which results in the serious changes in fracture characteristics of HAZ (heat-affected zone). Nevertheless, the systematic study on material heterogeneity of weldment has not been performed yet in Korea. Therefore in this paper, the effects of material heterogeneity on the fracture toughness of structural steel HAZ were introduced and reviewed.

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Evaluation of Filling Performance of Steel Concrete Panel (SCP) Mock-up Member with Low-binder based High-fluidity Concrete (저분체 기반 고유동 콘크리트의 Steel Concrete Panel Mock-up 부재 충전 성능 평가)

  • Park, Gi Joon;Park, Jung Jun;Kim, Sung Wook
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.39 no.4
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    • pp.477-483
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    • 2019
  • Recently, precast type SCP modules are being used instead of PSC structures in order to reduce the construction period and costs of special structures such as nuclear power plants and LNG storage tanks. The inside of the SCP module is connected with a stud for the integral behavior of the steel and concrete, and the use of high fluidity concrete is required. High fluidity concrete generally has a high content of binder, which leads to an increase in hydration heat and shrinkage, and a problem of non-uniform strength development. Therefore, in this study, fluidity and passing performance of high fluidity concrete according to material properties are investigated to select optimum mix design of low binder based high fluidity concrete. Mechanical properties of high fluidity concrete before and after pumping are examined using pump car. The filling performance of SCP mock-up members was evaluated by using high fluidity concrete finally.

Damage Evaluation of Bi-directionally Prestressed Concrete Panels under Blast-fire Combined Loading (폭발 후 화재하중 시나리오에 따른 2방향 프리스트레스트 콘크리트 패널부재의 손상도 평가)

  • Choi, Ji-Hun;Choi, Seung-Jai;Kim, Tae-Kyun;Kim, Jang-Ho Jay
    • Journal of the Korea Concrete Institute
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    • v.29 no.3
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    • pp.237-248
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    • 2017
  • Frequent terror or military attack by explosion, impact, fire accidents have occurred recently. These attacks and incidents raised public concerns and anxiety of potential terrorist attacks on important infrastructures. However, structural behavioral researches on prestressed concrete (PSC) infrastructures such as Prestressed Concrete Containment Vessel (PCCV) and Liquefied Natural Gas (LNG) storage tanks under extreme loading are significantly lacking at this time. Also, researches on possible secondary fire scenarios after terror and bomb explosion has not been performed yet. Therefore, a study on PSC structural behavior from an blast-induced fire scenario was undertaken. To evaluate the blast-fire combined resistance capacity and its protective performance of bi-directional unbonded PSC member, blast-fire tests were carried out on $1,400mm{\times}1,000mm{\times}300mm$ PSC specimens. Blast loading tests were performed by the detonation of 25 kg ANFO explosive charge at 1.0 m standoff distance. Also, fire and blast-fire combined loading were tested using RABT fire loading curve. The test results are discussed in detail in the paper. The results can be used as basic research references for related research areas, which include protective design simulation under blast-fire combined loading.