简介：Oneofthemainconcernsinusingcommercialsoftwareforfiniteelementanalysesofdam-foundation-reservoirsystemsisthatthesimplifyingassumptionsofthemasslessfoundationareunreliable.Inthisstudy,anappropriatedirectfiniteelementmethodisintroducedforsimulatingthemass,radiationdampingandwavepropagationeffectinfoundationsofdamfoundation-reservoirsystemsusingcommercialsoftwareABAQUS.Thefree-fieldboundaryconditionisusedformodelingthesemi-infinitefoundationandradiationdamping,whichisnotabuilt-inboundaryconditioninmostoftheavailablecommercialsoftwareforfiniteelementanalysisofstructuressuchasANSYSorABAQUSandthusneedstobeimplementeddifferently.Thedifferentmechanismformodelingofthefoundation,earthquakeinputandfar-fieldboundaryconditionisdescribed.Implementationofthefree-fieldboundaryconditioninfiniteelementsoftwareisverifiedbycomparingitwithanalyticalresults.Toinvestigationthefeasibilityoftheproposedmethodindam-foundation-reservoirsystemanalysis,aseriesofanalysesisaccomplishedinavarietyofcasesandtheobtainedresultsarecomparedwiththesubstructuremethodbyusingtheEAGD-84program.Finally,themassedandmasslessfoundationresultsarecomparedanditisconcludedthatthemasslessfoundationapproachleadstotheoverestimationofthedisplacementsandstresseswithinthedambody.

简介：Largeamplitudevibrationofmastarmstructuresduetowindloadsaretheprimarycontributingfactortothereducedfatiguelifeofsignalsupportstructures.Toalleviatethisproblemofwind-inducedin-planevibrationofmastarmsignalstructures,aparticle-thrustdampingbasedturnedmassdamper(PTD-TMD)deviceisadoptedanditsdampingeffectischaracterizedexperimentally.Theparticle-thrustdampingisapassivedampingdevicethatdoesnotrequireelectricpowerandistemperatureindependent.Basedonthecalibrationtest,anequivalentdynamicmodelofthePTD-TMDdeviceisdevelopedandusedfornumericalsimulationstudy.ThedampingeffectsofthisPTD-TMDdeviceonsignalsupportstructureswasinvestigatedthroughbothnumericalanalysisandlaboratorytestingofa50-ft(15.24m)mastarmstructureincludingbothfreevibrationandforcedvibrationtests.TheexperimentaltestandnumericalstudyresultsshowthatvibrationresponsebehaviorofmastarmsignalsupportstructurescanbesignificantlyreducedbyinstallingthePTD-TMDthatcanincreasethecriticaldampingratioofthemastarmsignalstructuresto4%.Thestressrangeattheweldedconnectionbetweenthemastarmandtrafficpoleisalsoreduced.