• International Journal of Naval Architecture and Ocean Engineering
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• 제8권2호
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• pp.153-168
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• 2016

Sloshing phenomenon is a complicated free surface flow problem that increases the dynamic pressure on the sidewalls and the bottom of the storage tanks. When the storage tanks are partially filled, it is essential to be able to evaluate the fluid dynamic loads on the tank's perimeter. In this paper, a numerical code was developed to determine the pressure distribution on the rectangular and trapezoidal storage tanks' perimeters due to liquid sloshing phenomenon. Assuming the fluid to be inviscid, the Laplace equation and the nonlinear free surface boundary conditions were solved using coupled boundary element - finite element method. The code performance for sloshing modeling was validated using Nakayama and Washizu's results. Finally, this code was used for partially filled rectangular and trapezoidal storage tanks and free surface displacement, pressure distribution and horizontal and vertical forces exerted on the tanks' perimeters due to liquid sloshing phenomenon were estimated and discussed.

• Structural Engineering and Mechanics
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• 제65권5호
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• pp.557-572
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• 2018

The academic research works about liquid storage tanks are reviewed for the purpose of providing valuable reference to the engineering practice on their aseismic design. A summary of the performance of tanks during past earthquakes is described in this paper. Next, the seismic response of tanks under unidirectional earthquake is reported, supplemented with the dynamic response under multidirectional motions. Then, researches on the influence of soil-structure interaction are brought out to help modify the seismic design approach of tanks in different areas with variable properties of soils. Afterwards, base isolation systems are reported to demonstrate their effectiveness for the earthquake-resistant design of liquid storage tanks. Further, researches about the liquid-structure interaction are reviewed with description of simplified models and numerical analytical methods, some of which consider the elastic effect of tank walls. Moreover, the liquid sloshing phenomenon on the hydrodynamic behaviors of tanks is presented by various algorithms including grid-based and meshfree method. And then the impact of baffles in changing the dynamic characteristics of the liquid-structure system is raised, which shows the energy dissipation by the vortex motion of liquid. In addition, uplifting effect is given to enhance the understanding on the capacity of unanchored tanks and some assessment of their development. At last, the concluding remarks and the aspects of extended research in the field of liquid storage tanks under seismic loads are provided, emphasizing the thermal stress analysis, the replaceable system for base isolation, the liquid-solid interaction and dynamic responses with stochastic excitations.

• Earthquakes and Structures
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• 제2권4호
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• pp.397-412
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• 2011

In this paper, the seismic response of elevated broad and slender liquid storage tanks isolated by elastomeric or sliding bearings was investigated. The accuracy of predictions of SAP2000 vs. 3D-BASIS-ME programs was examined. A comparative study of the performance of base isolated tanks when isolation bearings are placed at the top or at the bottom of the supporting tower structure was conducted. It was found that base isolation is quite effective in reducing the earthquake response of elevated liquid storage tanks in which high reductions of base shear and shaft displacement were achieved. Modeling the isolated tanks in SAP2000 was very successful in producing results that are nearly identical to those of program 3D-BASIS-ME. Placing the isolators at the top of the shaft in elevated tanks proved to be much better than placing them at the bottom.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.683-688
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• 2001

Cryogenic LNG(Liquefied Natural Gas) which is stored in the cylindrical storage tanks of $100,000m^{3}$ has very complex flow phenomena and the changes of thermal properties with exterior conditions and operation mdoes. These complex thermofluid behaviors are affected by the storage, exterior conditions of LNG, design specifications and heat transfer characteristics of tanks, Also, those have influence on the stable storage and supply of LNG in the storage tanks. Thus this study performed the analysis on the 2-D heat transfer of the tank with exterior conditions, on the Cool Down Process in order to cool down the LNG Storage Tank at the initial normal state, and on the Filling Process considered for incoming and rising of LNG. The analysis on the Mixing LNG Storage was studied too. At last, the visualized program on the complex thermofluidodynamic analysis was developed on the basis of the above analyses. The development of this program becomes to be used to the basic design of the commercial tanks as well as to assure technical skill of the analysis on the thermal stability of the stored LNG in the LNG Storage Tank.

• 한국가스학회지
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• 제16권6호
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• pp.48-54
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• 2012

최근 LNG 저장탱크 시장에서는 지상식 멤브레인 LNG 저장탱크의 대용량화 용이성, 친환경성, 내부탱크로부터의 낮은 누출 가능성(완만한 누출속도의 증가) 등의 장점으로 동 탱크의 건설에 대한 적극적인 검토가 이루어지고 있다. 이 논문에서는 고장수목분석법(FTA)을 활용하여 기존의 완전방호식 LNG 저장탱크와의 비교 위험성평가를 통해 멤브레인 LNG 저장탱크의 안전성을 분석하였다. 위험성평가 결과는 추가적인 안전장치를 갖지 않는 초기 멤브레인 LNG 저장탱크를 제외하고 두 형식의 LNG 저장탱크가 매우 유사한 위험수준을 가지는 것으로 나타났다.

• 한국지진공학회논문집
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• 제22권7호
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• pp.401-409
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• 2018

Performance-based seismic evaluation is usually done by considering simplified models for the liquid storage tanks therefore, it is important to validate those simplified models before conducting such evaluation. The purpose of this study is to compare the seismic response results of the FSI (fluid-structure interaction) model and the simplified models for the cylindrical liquid storage tanks and to verify the applicability of the simplified models for estimating failure probability. Seismic analyses were carried out for two types of storage tanks with different aspect ratios (H/D) of 0.45 and 0.86. FSI model represents detailed 3D fluid-structure interaction model and simplified models are modeled as cantilever mass-spring model, frame type mass-spring model and shell type mass-spring model, considering impulsive and convective components. Seismic analyses were performed with modal analysis followed by time history analysis. Analysis results from all the models were verified by comparing with the results calculated by the code and literature. The results from simplified models show good agreement with the ones from detailed FSI model and calculated results from code and literature, confirming that all three types of simplified models are very valid for conducting failure probability analysis of the cylindrical liquid storage tanks.

• Structural Engineering and Mechanics
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• 제35권6호
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• pp.759-772
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• 2010

Seismic isolation is a well-known method to mitigate the earthquake effects on structures by increasing their fundamental natural periods at the expense of larger displacements in the structural system. In this paper, the seismic response of isolated and fixed base vertical, cylindrical, liquid storage tanks is investigated using a Finite Element Model (FEM), taking into account fluid-structure interaction effects. Three vertical, cylindrical tanks with different ratios of height to radius (H/R = 2.6, 1.0 and 0.3) are numerically analyzed and the results of response-history analysis, including base shear, overturning moment and free surface displacement are reported for isolated and non-isolated tanks. Isolated tanks equipped by lead rubber bearings isolators and the bearing are modeled by using a non-linear spring in FEM model. It is observed that the seismic isolation of liquid storage tanks is quite effective and the response of isolated tanks is significantly influenced by the system parameters such as their fundamental frequencies and the aspect ratio of the tanks. However, the base isolation does not significantly affect the surface wave height and even it can causes adverse effects on the free surface sloshing motion.

• 한국가스학회지
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• 제19권4호
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• pp.62-67
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• 2015

본 논문에서는 LPG 소형저장탱크의 보급확대에 따른 위험성감소 방안으로 소형저장탱크의 지상 및 지하매몰 설치에 대한 피해영향평가를 수행하였다. 지하에 설치된 소형저장탱크의 피해영향평가를 수행하기 위해 FDS를 활용하여 격납형으로 설치된 소형저장탱크를 모사하였고, FDS로부터 소형저장탱크실의 최대 압력을 도출하여 피해영향 평가 프로그램인 Phast의 입력변수로 활용하였다. 지상 및 지하에 설치된 소형저장탱크의 각각의 피해영향평가를 시뮬레이션을 통해 연소하한계(LFL) 및 연소상한계(UFL)의 확산범위, 고압분출화재(Jet fire), 폭발 등 피해영향을 정량적인 수치로 제시하였다.

• 에너지공학
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• 제21권4호
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• pp.339-345
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• 2012

최근 안정성 및 경제성 측면에서 완전방호식 LNG 저장탱크(full-containment LNG storage tank)의 대안으로 검토되고 있는 멤브레인 LNG 저장탱크(membrane LNG storage tank)에 대해서 정량적 위험성 평가 방법(QRA; Quantitative Risk Analysis)과 유한요소해석법(FEM; Finite Element Method)을 통하여 안전성 평가를 수행하였다. 본 논문에서는 유한요소해석법(FEM)을 통한 구조안전성 평가에서 140,000 $m^3$ 저장용량을 갖는 LNG 저장탱크의 두 가지 모델은 저장탱크 시스템에 대한 강도 안전성과 누출 안전성 측면에서 해석한 결과에 의하면 모두 안전한 것으로 평가되었다. 또한, 고장수목분석(FTA; Fault Tree Analysis)을 통하여 멤브레인 LNG 저장탱크에 안전성을 강화하기 위해 설계 초기모델에 안전장치로서 멤브레인 바닥부의 충격흡수장치(impact absorber structure), 1차 멤브레인 저장 파손 시 콘크리트 외부탱크(outer tank) 코너부(corner part)의 열충격(thermal stress)을 감소시킬 수 있는 열보호장지(secondary barrier) 및 펌프 낙하 시 안전장치로서 펌프캐쳐(pump catcher)를 보완하고 평가하였다. 결론적으로 개선된 멤브레인 LNG 저장탱크는 안전성 측면에서 완전방호식 LNG 저장탱크와 대등하다는 결론을 도출할 수 있었다.

• 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.