37663594-Rectangular-Tank-Example-Latest

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1、ADesignExampleforaRectangularConcreteTankPCADesignMethodCVEN4830/4434UniversityofColorado,BoulderSpringSemester2008PreparedbyBenBlackardThePortlandCementAssociation(PCA)haspublicationsfordesigningrectangularandcirculartanks.Someofthedesignprovisionsdifferfromthato

2、ftheAmericanConcreteInstitute(ACI)specifications.ManyintheindustryusethesePCAdesignconcepts,sowewilladaptthemforourcalculationsaswell.MuchofthePCApublicationiscomprisedoftablesofcoefficientsforcalculatingmomentandshearintwo-wayslabs.Thesetablesshouldsimplifythecal

3、culations.WewillrefertothePCARectangularConcreteTanksdesignmanualasPCA-R,andthecirculartankdesignmanualasPCA-C.Anadditionalsafetyfactorisusedfortheloadscalledthe“SanitationCoefficient”,wewilldenoteitwithSCforbrevity.Notethatthisnotationisnotanindustrystandard.Thep

4、urposeofthesanitationcoefficientistoindirectlyreducethestress,andthusthestrain,inthesteelreinforcing.Theresultislowerstrainintheconcrete,andthuslesscracking.TheultimateloadwillbemultipliedbySC,whichhasdifferentvaluesfordifferentcalculations:1.3forflexureSC=1.65for

5、directtension(hooptensilestressinreinforcing)1.0shearprovidedbyconcrete1.3forshearbeyondthatprovidedbyconcreteAnotherchangeisthefluidloadfactoris1.7ratherthan1.4asstatedintheACIspecification.Forthepurposesofthisclass,thefollowingloadcombinationsandfactorswillbeuse

6、d:Mu=1.3(1.4D+1.7F+1.6H)forflexurePu=1.65(1.4D+1.7F+1.6H)fordirecttension(hooptensilestressinreinforcing)Pu=1.0(1.4D+1.7F+1.6H)fordirectcompression(hoopcompressionstressinconcrete)Vu=1.0(1.4D+1.7F+1.6H)shearprovidedbyconcreteVu=1.3(1.4D+1.7F+1.6H)forshearbeyondtha

7、tprovidedbyconcreteD=deadloadF=fluidpressureH=earthpressureRectangularConcreteTankDesignExampleAnopentopconcretetankistohavethreechambers,eachmeasuring20′×60′asshown.Thewallheightis17′.Thetankwillbepartiallyunderground,thegradelevelis10′belowthetopofthetank.Thehig

8、hestgroundwatertableisexpectedtobe4′belowgrade.Thefluidlevelinsidethetankis15′.60′20′20′20′f′c=3,500psify=60,000psisoilbearingcapacity=2,700psfWallsabov