VariablefrictionpendulumsystemforseismicisolationofliquidstoragetanksOriginalResearchArticle

Earthquakeresponseofliquidstoragesteeltanksisolatedwithvariablefrictionpendulumsystem(VFPS)isinvestigatedundernormalcomponentofsixrecordednear-faultgroundmotions.Thecontinuousliquidmassofthetankismodeledaslumpedmassesknownassloshingmass,impulsivemassandrigidmass.Thecorrespondingstiffnessconstantsassociatedwiththeselumpedmassesareworkedoutdependinguponthepropertiesofthetankwallandliquidmass.ThegoverningequationsofmotionofthetanksisolatedwithvariablefrictionpendulumsystemarederivedandsolvedbyNewmarkʹsstep-by-stepmethodassuminglinearvariationofaccelerationoversmalltimeinterval.InordertoverifytheeffectivenessoftheVFPSintanks,theseismicresponseoftanksisolatedwithVFPSiscomparedwiththatofthesametanksisolatedusingtheconventionalfrictionpendulumsystem(FPS).Furthermore,aparametricstudyisalsocarriedouttocriticallyexaminethebehaviouroftanksisolatedwithVFPS.Thevariousimportantparametersconsideredarethetankaspectratio,theisolationperiodandinitialtimeperiodoftheVFPS.Inaddition,theseismicresponseoftanksisolatedwithVFPSundertrigonometriccycloidalpulsesisalsoinvestigated.Fromtheseinvestigations,itisconcludedthatwiththeinstallationofVFPSintanks,theseismicresponseoftanksduringnear-faultgroundmotionscanbecontrolledwithinadesirablerange.Finally,itisalsoobservedthattheresponseoftanksisolatedwithVFPSunderthenear-faultgroundmotionsandtrigonometriccycloidalpulsesmatcheswellonlywhentheisolationperiodreacheshighvalues.