impactul dezastrelor

7/29/2019 impactul dezastrelor

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Numerical and Wind-TunnelSimulation of Wind Loads onSmooth and Rough Domes

R.N. Meroney

C.W. LetchfordP.P. Sarkar


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Powerpoint Presentations!


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Structural Domes

Domes are commonly used to encloselarge spaces because of their structuralefficiency and economic benefit.

Domes are excellent at resistingsymmetric loading, but

Asymmetric loading may causestructural distress and failure.


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Domed Sports Halls & Stadiums

HoustonAstrodome

Hubert H. HumphreyMetro-Dome, Min

Little Sports Palace, Rome

Pepsi Center, Denver

Sun Dome, Fukui, Japan


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Assembly Hall Dome

Assembly Hall, U. ofIllinois Urbana/Champ


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Domed PublicBuildings

^ Public Exhibition HallsMillennium Dome, London,320 m diameter, 80,000 sq m

floor space

Museums and Halls,Barlow Planetarium, CA

^


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Inflated Domes

US Pavilion, OsakaExposition 1970

Carrier Stadium,Syracuse University

Georgia Dome, Atlanta Silverdome, Pontiac, MI

RCA (Hoosier) Dome

Indianapolis, IN


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Inflated Domes (contd)

Tokyo DomeBig Egg Stadium,

Tokyo, Japan


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Bulk Storage: Dust Supression, Waterand Wastewater Treatment Covers

Temcor Aluminum DomesTriangulated space truss system with

triangulated panels


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Bulk Storage: Coke Piles

Pittsburgh, CA Marine Terminal Coke Storage DomesThree 55 m (180 ft) diameter hemispheres

Los Angeles, CA Export Terminal Coke Storage Domes ConstructionTwo 73 m (240 ft) diameter hemispheres, Shotcrete applied to interior

of inflated airform mounted on footer and stem wall


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Rough Surface Hemispheres

Sometimes construction technique leaves surface texture rough!


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CFD Validation Using Physical ModelingVERIFICATION BEFORE PROGNOSTICATION


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Wind Effects on

Hemispherical Domes

Inflated domes requireinternal pressuresexceeding external

pressures to avoidbuckling.

Internal pressures mustnot be too large or

excessive membrane ortensile forces occur, andmembrane tears.


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Wind-tunnel Study ofInflated Domes

1

2

3

Newman, Ganguli andShrivastava (1984) studiedpressure distributions onthree inflatable domes in a

boundary layer. H/D = 0.5, 0.37 & 0.25,

H/=0.12-0.13, U=7.5m/s, Re=UD/=226,000

FEM calculations showbuckling occurs on plane ofsymmetry and upwind whenthe internal inflationpressures < 0.7-0.44 of thedynamic pressure at thedome top.


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CSU WEFL Wind Tunnel Experiment

PressureScanner

PressureTransducer

CSU WEFL Industrial Aerodynamics Wind Tunnel

PC-NTComputer

PostprocessSoftware

Hot FilmAnemometer


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Wind-Tunnel Initial Conditions

Grid: 86,000 cells

Velocity Contours:

Umax = 15 m/s

Z = 1m

Z = 0.8 m

ASCE 7-98C

Windtunnel


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Grid Systems: One and Two Domes

18,000 Cells 33,000 Cells 16,400 Cells

43,000 Cells


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Hemisphere Grids

Boundary layer & Hex Grid Boundary layer & Tet Grid


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Velocity & Turbulence Profiles:Single Dome Comparisons


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Single Dome Comparisons:Pressure Profiles


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Single Dome Comparisons:Reynolds Number Variation

Reynolds Number =(U H/) = 185,000

Reynolds Number =(U H/) =

1,440,000

Conclusion: Nosignificant difference


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Single Dome Comparisons:Turbulence Models

Standard kappa-epsilon model

(2 equations) Reynolds stress

model (7 equations)

Spalart Allmaras

model (1 equation) Conclusion: No

significant difference


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Single Dome Comparisons:Pressure Profiles


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Single Dome Comparisons:Smooth vs Rough


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Double Dome ComparisonsApproach wind at 90o


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Surface Pressures:Angles 0o, 45o & 90o


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Pressure Coefficient Contours:

Experimental vs Numerical:Approach wind at 0o

Cp Contours: numerical

Cp Contours:experimental

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Pressure Coefficient Contours:Experimental vs Numerical:

Approach wind at 90o

Cp Contours: numerical

Cp Contours:experimental


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Conclusions

CFD calculations reproduced mean Cpbehavior over smooth, rough and paired

domes. CFD calculations using k-, RNG, and

Rey turbulence models gave similarresults.

CFD calculations at high and lowReynolds numbers gave similar results.


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WHALE WATCHING

IS NOT AN

EMERGENCY KEEP

DRIVING

GOOD LUCK

Approaching the End


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The End

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