ABOVE GROUND fULL CONTAINMENT LNG STORAGE TANK.docx

http://www.lusas.com/case/civil/lng_ta http://www .lusas.com/case/civil/lng_tank_design.html nk_design.html Design and analysis of above-ground full containment LNG storage tanks •

Development of the world's largest above ground LNG tank

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Static, dynamic, thermal and nonlinear analysis

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Strict design requirements met

!G"S Gas #echnology $orporation %!G"S&#ech is using L(S"S Civil & Structural  software  software to help develop and continually improve its range of above ground full containment Liquified Natural Gas tanks) *ith the assistance of L(S"S of  L(S"S engineering consultancy services LNG services  LNG storage tank / si+es of -.,...m  were initially developed but now, using L(S"S Civil & Structural , Structural , an above / ground full containment LNG tank with a capacity of 0..,...m  has been analysed and optimised) *hen completed it became the largest above ground full containment LNG storage tank in the world) #ank development

Over the years KOGAS-Tech has develoed t!o distinct tyes of above-ground ost-tensioned concrete containment tanks" One involves the use of a rorietary inner membrane system# and the other comrises a steel nickel inner tank lining" $oth are of a %&'#'''m ( caacity and have been installed at the )yeongtaek and Tongyeong facilities in South Korea" *ith the use of L+SAS soft!are KOGAS-Tech has no! develoed a ,''#'''m( above ground tank for the )yeongtaek facility" Similar in nature to its smaller brother it has a (".m high nickel steel inner tank of  /&m diameter insulated from a /."&m inside diameter ost-tensioned concrete !all" The steel tank sits on a concrete base slab suorted by small diameter iles at close centres" The overall tank height to the to of the roof slab is 0,"/m" "nalyses undertaken 1n analysing and develoing its range of tanks KOGAS-Tech erforms numerous finite element analyses !ith L+SAS including2 •

Static analysis

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*ind loading

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3odal and seismic analysis

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Temerature modelling

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Leakage modelling

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)restress 4 ost-tensioning

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$urn-out modelling

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5elief valve heat flu6 modelling

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Soil-structure interaction

Static analysis 7or static analysis# ,D a6isymmetric solid element and (D shell element models are built and numerous static linear analysis loadcases are defined for various arts of the structure !ith the roof# the !alls# the base slab etc being loaded indeendently" Load combinations then allo! the effects of the multile loadcases to be assessed" 1odal analysis (D shell element modelling and eigenvalue analysis of the LNG tank outer shells and ressure relief latforms involves an e6amination of both the uncouled and couled resonse of the t!o structures"

Lumed mass modelling is used for fluid4structure interaction of the LNG and for soil4structure interaction of the ile arrangements"

*ind load modelling

Seismic analysis

(D shell element modelling is used to carry out !ind load analysis of the LNG tank outer shell" 7or this analysis# half-models can often be used due symmetry of both tank geometry and loading" The !ind load is varied around the circumference of the outer !alls using a 7ourier distribution roviding a normal ressure on the for!ard face of the structure and a suction to the rear face"

1nteractive 3odal Dynamics techni8ues are used in the calculation of the dynamic seismic resonse" Oerational $asis 9arth8uake :O$9; and Safe Shutdo!n 9arth8uake analysis assessments are also run to satisfy code re8uirements" The generated data from the structural analysis is integrated to obtain base shear forces and bending moments in the !all"

#hermal modelling 7or thermal modelling# ,D a6isymmetric solid field and continuum elements are used and a semi-couled steady state thermal analyses of LNG tank outer !alls !ith insulation is erformed" 7or this# an initial stress-free temerature is alied to all elements# and combinations of environmental conditions are considered for both the air and base temeratures" 5esults lots of hoo stresses in the to and bottom corners caused by a steady state thermal load are roduced"

To corner modelling

$ottom corner modelling 5esults lots of hoo stresses in the to and bottom corners caused by a steady state thermal load are roduced"

Leakage modelling Leakage modelling analysis investigates the effect of LNG sillage from the inner steel tank onto the )olyurethane 7oam :)+7; insulation on the inside of the outer concrete tank at five different heights" The tank insulation is assumed to have been comletely destroyed u to each level of the LNG under consideration" ,D a6isymmetric solid field and continuum elements are used to model the tank outer !alls and insulation do!n to the to of each leakage level" A semi-couled steady state thermal analysis is carried out to assess the effects of the leakage"

1odelling prestress tensioning Large temorary oenings in the !all mean that it is necessary to limit the effects of stress concentration caused by restress forces" Loadings for each set of  cables# both hori and a secified mean annual e6ternal temerature"  A heat flu6 is then be alied to a secified region on the to of the roof for the number of time stes under consideration"

"Using LUSAS allows us to continuously improve our analysis, research and development capability especially in nonlinear analysis. With LUSAS we can ensure that our range o L! tan# designs always meets the strict design re$uirements o our clients."