简介：ThispaperanalyzestheseismicityandseismicriskdistributionintheBohaiSea.Basedontheseismicdesignparametersof46platformsintheBohaiSea,astatisticanalysisismadeontheratiosofthepeakaccelerationsfordifferentprobabilitylevels.Inaccordancewiththetwo-stagedesignmethod,aschemeoftwodesignseismiclevelsisproposed,andtwofortificationgoalsareestablishedrespectivelyforstrengthlevelearthquakesandductilitylevelearthquakes.ThroughanalogyandcomparisontotheChineseseismiccodeforbuildings,itisproposedthattheprobabilitylevelforthestrengthandductilitylevelearthquakestakesreturnperiodsof200aand1000～2500arespectively,andwefurtherexpoundedonitsrationality.Finally,thefortificationparametersinthesub-regionsofBohaiSeaareaaregiveninthelightofseismicriskzonationandgroundmotiondivision.Thisarticleisasummaryofexperiencesfrommanyyearsofoffshoreplatformseismicfortificationwork,andanexploratorystudyontheseismicfortificationstandardsofoffshoreplatformsinChina,whichmayprovidesomereferencesfortheestablishmentofthestandard.

简介：

简介：OnJune22,1518,alargeearthquake,measuringM71/2,occurredoffshorewestofSeoul,KoreainthesouthernYellowSea.ThisearthquakeaffectedthewholeKoreanPeninsula,andcauseddamagetothecoastalareassuchasSeoul,wheretheseismicintensitywasdegreeⅧ.Aftershockactivitylastedformorethanonemonth.TheearthquakealsoaffectedtheEasternChinaregion.ThisearthquakewaspossiblyrelatedtotheactivityofthewesternmarginfaultzoneoftheKoreanPeninsula(theeasternmarginfaultzoneofthesouthernYellowSea).Theepicenteroftheearthquakewaslocated36.5°Nand125.2°E.

简介：

简介：Thedynamicequationsofmotionofasymmetricoffshoreplatformsunderthreedifferentenvironmentalconditions:seismicaction,waveactionandtheircombinationareestablishedinthispaper.Inestablishingthesemotionequations,threetypicaleccentricitytypesincludingmasseccentricity,rigidityeccentricityandtheircombinationwereconsidered,asareeccentricitiesthatoccurun-idirectionallyandbi-directionally.Theeffectsoftheeccentricitytype,thedynamiccharacteristicsandtheenvironmentalconditionsonthetorsionalcouplingresponseofplatformsareinvestigatedandcompared.Anefforthasalsobeenmadetoanalyzetheinffluenceofaccidentaleccentricityonasymmetricplatformswithdifferenteccentricityintwohorizontallyorthogonaldirections.Theresultsaregivenintermsofnon-dimensionalparameters,accountingfortheuncoupledtorsionaltolateralfrequencyratio.Numericalresultsrevealthattheeccentricitytypehasagreatinffluenceonthetorsionallycoupledresponseunderdifferentenvironmentalconditions.Therefore,itisnecessarytoconsiderthecombinationofearthquakeandwaveactionintheseismicresponseanalysisofsomeoffshoreplatforms.

简介：Themainintentionofthepresentstudyistoreducewind,wave,andseismicinducedvibrationsofjackettypeoffshorewindturbines(JOWTs)throughanewlydevelopedvibrationabsorber,calledtunedliquidcolumngasdamper(TLCGD).UsingaSimulink-basedmodel,ananalyticalmodelisdevelopedtosimulateglobalbehaviorofJOWTsunderdifferentdynamicexcitations.ThestudyisfollowedbyaparametricstudytoexploreefficiencyoftheTLCGDintermsofnacelleaccelerationreductionunderwind,wave,andearthquakeloads.StudyresultsindicatethatoptimumfrequencyoftheTLCGDisratherinsensitivetoexcitationtype.Inaddition,whilethegaininvibrationcontrolfromTLCGDswithhighermassratiosisgenerallymorepronounced,heavyTLCGDsaremoresensitivetotheirtunedfrequencysuchthatill-regulatedTLCGDwithhighmassratiocanleadtodestructiveresults.ItisrevealedthatawellregulatedTLCGDhasnoticeablecontributiontothedynamicresponseoftheJOWTunderanyexcitation.