简介：Thispaperpresentsamodifiedhalf-sine-squaredloadmodelofthejumpingimpulsesforasingleperson.Themodelisbasedonadatabaseof22,921experimentallymeasuredsinglejumpingloadcyclesfrom100testsubjects.Threedimensionalmotioncapturetechnologyinconjunctionwithforceplateswasemployedintheexperimenttorecordjumpingloads.Thevariationrangeandprobabilitydistributionofthecontrollingparametersfortheloadmodelsuchastheimpactfactor,jumpingfrequencyandcontactratio,arediscussedusingtheexperimentaldata.Correlationrelationshipsbetweenthethreeparametersareinvestigated.Thecontactratioandjumpingfrequencyareidentifiedasindependentmodelparameters,andanempiricalfrequency-dependentfunctionisderivedfortheimpactfactor.Thefeasibilityoftheproposedloadmodelisestablishedbycomparingthesimulatedloadcurveswithmeasuredones,andbycomparingtheaccelerationresponsesofasingle-degree-of-freedomsystemtothesimulatedandmeasuredjumpingloads.Theresultsshowthatarealisticindividualjumpingloadcanbegeneratedbytheproposedmethod.Thiscanthenbeusedtoassessthedynamicresponseofassemblystructures.

简介：Thispaperdescribesaquasi-statictestprogramfeaturinglateralcyclicloadingonsinglepilesinsandysoil.Thetestswereconductedon18aluminummodelpileswithdifferentcrosssectionsandlateralloadeccentricityratios,e/d,(eisthelateralloadeccentricityanddisthediameterofpile)of0,4and8,embeddedinsandwitharelativedensityof30%and70%.Theexperimentalresultsincludelateralload-displacementhysteresisloops,skeletoncurvesandenergydissipationcurves.Lateralcapacity,ductilityandenergydissipationcapacityofsinglepilesunderseismicloadwereevaluatedindetail.Thelateralcapacitiesandtheenergydissipationcapacityofpilesindensesandweremuchhigherthaninloosesand.Whenembeddedinloosesand,themaximumlateralloadandthemaximumlateraldisplacementofpilesincreasedase/dincreased.Onthecontrary,whenembeddedindensesand,themaximumlateralloadofpilesdecreasedase/dincreased.Pileswithahigherloadeccentricityratioexperiencedhigherenergydissipationcapacitythanpileswithe/dof0inbothdenseandloosesand.Atagivenlevelofdisplacement,pileswithcircularcrosssectionsprovidedthebestenergydissipationcapacityinbothlooseanddensesand.

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简介：Thesingle-layerlatticedcylindricalshellisoneofthemostwidelyadoptedspace-framedstructures.Inthispaper,freevibrationpropertiesanddynamicresponsetohorizontalandverticalseismicwavesofsingle-layerlatticedcylindricalshellsareanalyzedbythefiniteclementmethodusingANSYSsoftware.Inthenumericalstudy,wherehundredsofcaseswereanalyzed,theparametersconsideredincludedrise-spanratio,length-spanratio,surfaceloadandmembersectionsize.Moreover,tobetterdefinetheactualbehaviorofsingle-layerlatticedshells,thestudyisfocusedonthedynamicstressresponsetobothaxialforcesandbendingmoments.Basedonthenumericalresults,theeffectsoftheparametersconsideredonthestressesarediscussedandamodifiedseismicforcecoefficientmethodissuggested.Inaddition,someadvicebasedontheserescarchresultsispresentedtohelpinthefuturedesignofsuchstructures.

简介：Horizontalimpedancefunctionsofinclinedsinglepilesaremeasuredexperimentallyformodelsoil-pilesystemswithboththeeffectsoflocalsoilnonlinearityandresonantcharacteristics.Twopracticalpileinclinationsof5掳and10掳inadditiontoaverticalpileembeddedincohesionlesssoilandsubjectedtolateralharmonicpileheadloadingsforawiderangeoffrequenciesareconsidered.Resultsobtainedwithlow-to-highamplitudeoflateralloadingsonmodelsoil-pilesystemsencasedinalaminarshearboxshowthatthelocalnonlinearitieshaveaprofoundimpactonthehorizontalimpedancefunctionsofpiles.Horizontalimpedancefunctionsofinclinedpilesarefoundtobesmallerthantheverticalpileandthevaluesdecreaseastheangleofpileinclinationincreases.Distinctvaluesofhorizontalimpedancefunctionsareobtainedforthe＇positive＇and＇negative＇cyclesofharmonicloadings,leadingtoasymmetricforce-displacementrelationshipsfortheinclinedpiles.Validationoftheseexperimentalresultsiscarriedoutthroughthree-dimensionalnonlinearfiniteelementanalyses,andtheresultsfromthenumericalmodelsareingoodagreementwiththeexperimentaldata.Sensitivityanalysesconductedonthenumericalmodelssuggestthattheconsiderationoflocalnonlinearityatthevicinityofthesoil-pileinterfaceinfluencetheresponseofthesoil-pilesystems.

简介：BasedonarrivaltimedataofseismicphasesofML≥2.0earthquakesmeasuredatShanxiDigitalSeismicNetworkfortheperiodfromJanuary2001toOctober2014,V_P/V_SintheShanxiregioniscalculatedusingtheWadatisinglestationandmulti-earthquakemethod,andaninvestigationisconductedintothevariationbehaviorofV_P/V_SintheShanxiregionbeforeandafterthethreeearthquakesofMS≥4.5in2010.OurstudyfindsthatabnormalV_P/V_Sappearedearlieratdistantstationsbeforeallofthethreeearthquakes,whichisatthetimerangefrom6monthsto1yearbeforetheearthquakes,andlateratnearstations,atthetimerange10daysto2monthsbeforeearthquakes.Therefore,itspossibletonarrowdownthescopeofthelocationinearthquakepredictionfromthedistantandnearstationdata.ThecalculationsofDongshanseismicstationindicatethatthesizeoftheresidualoftheorigintimehasimpactonthedetailofV_P/V_Svariation,thus,appropriatethresholdsshouldfirstlybesetfortheresidualsoforigintimeateachseismicstationinpracticalapplication,toensurescientificandsteadyV_P/V_Scalculations.