简介：Newmarkdesignspectrahavebeenimplementedinmanybuildingcodes,especiallyinbuildingcodesforcriticalstructures.PreviousstudiesshowthatNewmarkdesignspectraexhibitloweramplitudesathighfrequenciesandlargeramplitudesatlowfrequenciesincomparisonwithspectradevelopedbystatisticalmethods.Toresolvethisproblem,thisstudyconsidersthreesuitesofgroundmotionsrecordedatthreetypesofsites.Usingthesegroundmotions,influencesoftheshear-wavevelocity,earthquakemagnitudes,source-to-sitedistancesontheratiosofgroundmotionparametersarestudied,andspectrumamplificationfactorsarestatisticallycalculated.Spectralboundsforcombinationsofthreesitecategoriesandtwocasesofearthquakemagnitudesareestimated.Sitedesignspectrumcoefficientsforthethreesitecategoriesconsideringearthquakemagnitudesareestablished.TheproblemsofNewmarkdesignspectracouldberesolvedbyusingthesitedesignspectrumcoefficientstomodifythespectralvaluesofNewmarkdesignspectraintheaccelerationsensitive,velocitysensitive,anddisplacementsensitiveregions.

简介：Adesignofsemi-submersibleplatformismainlybasedontheextremeresponseanalysisduetotheforcesexperiencedbythecomponentsduringlifetime.Theexternalloadscaninducetheextremeairgapresponseandpotentialdeckimpacttothesemi-submersibleplatform.Itisimportanttopredictairgapresponseofplatformsaccuratelyinordertocheckthestrengthoflocalstructureswhichwithstandthewaveslammingduetonegativeairgap.Thewindloadcannotbesimulatedeasilybymodeltestintowingtankwhereasitcanbesimulatedaccuratelyinwindtunneltest.Furthermore,fullscalesimulationofthemooringsysteminmodeltestisstillatuffworkespeciallythestiffnessofthemooringsystem.Owingtotheabovementionedproblem,themodeltestresultsarenotaccurateenoughforairgapevaluation.Theaimofthispaperistopresentsensitivityanalysisresultsofairgapmotionwithrespecttothemooringsystemandwindloadforthedesignofsemi-submersibleplatform.Thoughthemodeltestresultsarenotsuitableforthedirectevaluationofairgap,theycanbeusedasagoodbasisfortuningtheradiationdampingandviscousdraginnumericalsimulation.Inthepresenteddesignexample,anumericalmodelistunedandvalidatedbyANSYSAQWAbasedonthemodeltestresultswithasimple4linesymmetricalhorizontalsoftmooringsystem.Accordingtothetunednumericalmodel,sensitivityanalysisstudiesofairgapmotionwithrespecttothemooringsystemandwindloadareperformedintimedomain.Threemooringsystemsandfivesimulationcasesaboutthepresentedplatformaresimulatedbasedontheresultsofwindtunneltestsandsea-keepingtests.Thesensitivityanalysisresultsarevaluableforthefloatingplatformdesign.