简介:Theproblemonthedynamicresponseofarigidembeddedfoundationinthepresenceofanundergroundrigidtunnelandsubjectedtoexcitationofincidentanti-planeSHwavesisanalyzed.Byusingtheexactanalyticalsolutionforthetwo-dimensionalSH-wavepropagationinandaroundboththesurfacerigidfoundationandsubsurfacerigidtunnel,thoseaspectsoftheresultinggroundmotionsthatareofspecialinterestandimportanceforseismicresistantdesigninearthquakeanalyseshavebeenexamined.Thecomputedamplitudesoftheresultingperiodicgroundmotionsdisplayaverycomplicatedwave-interferencebetweenthesurfacefoundationandundergroundtunnelthatleadtoobservedstandingwavepatterns,togetherwithabruptchangesinthewaveamplitudesandlargeamplificationoftheincidentmotions.
简介:地球作为triaxial被花僵硬身体,它在欧几里得的空格自由地旋转。开始的方程是Euler动态方程,与比比C的B和esmaller小的A。Euler方程被解决,并且数字结果被提供。在计算,下列参数被使用:(C~B)/A=0.00327353;(B-A)/C=0.00002196;(C-A)/e=0.00329549,并且地球的旋转的吝啬的尖速度,co=0.00007292115rad/s。计算证明除地球和它的旋转的免费Euler行列的自我旋转以外,那在那里存在免费点头:在theEarth的片刻的旋转轴和周期性地随着时间变化的吝啬的轴之间的点头角度,或角度。免费点头被调查。
简介:Asimplifiedfatigue-lifemodelisproposedforassessingtheseismicinelasticrotationalcapacityofsteelconnections.Firstrelationsaredevelopedforrigidsteelconnectionsunderlateralloading.Nextthisisextendedtoaccountfortheeffectsoftheweldedsteelmomentframe(WSMF)connectionsoftheso-calledpre-Northridgetype.Theseismicfatiguetheoryisvalidatedagainstexperimentalresults.Theexperimentswereconductedunderincreasingductilityamplitudcsuntiltheonsetoffracture.Miner'rulewasusedtoconvertthetestresultstogivenanequivalentconstantamplitudecyclicfatiguelife.Satisfactoryagreementisobtainedwhencomparingtheexperimentalobservationswiththetheoreticalpredictions.
简介:Inordertoaccountforrigid-flexiblecouplingeffectsoffloatingoffshorewindturbines,anonlinearrigid-flexiblecoupleddynamicmodelisproposedinthispaper.Theproposednonlinearcoupledmodeltakesthehigher-orderaxialdisplacementsintoaccount,whichareusuallyneglectedintheconventionallineardynamicmodel.Subsequently,investigationsonthedynamicdifferencesbetweentheproposednonlineardynamicmodelandthelinearoneareconducted.Theresultsdemonstratethatthestiffnessoftheturbinebladesintheproposednonlineardynamicmodelincreaseswithlargeroverallmotionsbutthatinthelineardynamicmodeldeclineswithlargeroverallmotions.Deformationofthebladesinthenonlineardynamicmodelismorereasonablethanthatinthelinearmodelaswell.Additionally,moredistinctcouplingeffectsareobservedintheproposednonlinearmodelthanthoseinthelinearmodel.Finally,itshowsthattheaerodynamicloads,thestructuralloadsandglobaldynamicresponsesoffloatingoffshorewindturbinesusingthenonlineardynamicmodelareslightlysmallerthanthoseusingthelineardynamicmodel.Insummary,comparedwiththeconventionallineardynamicmodel,theproposednonlinearcouplingdynamicmodelisahigher-orderdynamicmodelinconsiderationoftherigid-flexiblecouplingeffectsoffloatingoffshorewindturbines,andaccordmoreperfectlywiththeengineeringfacts.
简介:Beam-columnorbeam-wallconnectionsareanimportantprobleminhigh-risebuildings.Inthisstudy,basedontheanalysisofanexamplestructure,ananalyticalmodelfordesignofthesemi-rigidconnectionsbetweensteelbeamsandRCwallsinhigh-risehybridbuildingsisproposed.Also,themechanicalcharacteristicsoftheseconnectionssubjectedtolowreversedcyclicloadingareinvestigatedthroughcomparisonofexperimentalresultsfromthreesemi-rigidconnectionsandtworigidconnections.Moreover,somelatentproblemsfordesignoftheseconnectionsaswellasthecorrespondingsolutionsarediscussed.Theresultsfromtheexperimentsandanalysesindicatethatsemi-rigidconnectionsexhibitsatisfactorycapacityandseismicperformance,andtheproposeddesigncanbeusedinpractice.
简介:Athree-dimensionalrigidbodyontheshapeofaparallelepipedismodelledinordertorockonasideoravertexofthebase,inordertoevaluatetheseismicresponseofrigidblockslyingonahorizontalsupport.Thecenterofmassofthebodyisconsideredaseccentricwithrespecttoitsgeometriccenter.Asseismicinput,threeItalianrecordedaccelerograms,withdifferentspectralcontent,areused.Thestudyismainlyconductedtohighlightthedifferencesbetweentheseismicresponseof2Dand3Dmodelsofrigidblocks,withtheaimtounderstandif,insomecases,theuseofthe3Dmodelofrigidblockisrequiredtoobtainsaferresults.Infact,theoutcomesshowthatinsomerangesofthegeometricalandmechanicalparametersthatcharacterizetheexcitationandthebody,atwo-dimensionalmodel,whichisnotabletoconsiderthe3Drockingonavertex,canprovideunsaferesults.Inparticular,itisfoundthattheoverturningprocessofthethree-dimensionalblockcanoccurunderexcitationswhicharelowerthanthosewhichoverturnacorrespondingtwo-dimensionalblock.
简介:Themodelofrigidandelastic-plasticmotionandstraininintraplateblocksisestablishedinthepaper.Theuniqueofstrainparametersandminimumroot-mean-squareerrorofvelocityresidualofblocksaretestedinthemodel.BasedonthevelocityfieldsinChinesemainlandanditsperipheralareas,thestrainparametersof8blocksareestimatedandtheirstrainstatusanalyzed.Theestimatedstrainstatusofeachblockiswellconsistentwiththosederivedbythemethodsofgeologyandgeophysics.TheprincipaldirectionofcollisionforcefromIndiaplatetoEurasiaplateestimatedfromtheazimuthofprincipalcompressivestrainofHimalayablockmightbeN7.1°E.
简介:Toevaluatetheimportanceofthecanyontopographyeffectsonlargestructures,basedonarigidframebridgeacrossa137-m-deepand600-m-widecanyon,theseismicresponseofthecanyonsiteisanalyzedusingatwo-dimensionalfiniteelementmodelunderdifferentseismicSVwaveswiththeassumptionsofverticalincidenceandobliqueincidencetoobtainthegroundmotions,whichareusedastheexcitationinputonthepierfoundationsofthebridgewithimprovedlargemassmethod.Theresultsindicatethatcanyontopographyhassignificantinfluencesonthegroundmotionsintermsofincidentangle.Thepeakgroundaccelerationvaluesvarygreatlyfromthebottomofthecanyontotheuppercorners.UnderverticalincidentSVwaves,attheuppercornersofcanyonthepeakgroundaccelerationsgreatlyincrease;whereasthepeakgroundaccelerationsdiminishatthebottomcornersofcanyon.UnderobliqueincidentSVwaves,theshakingofthecanyonslopeperpendiculartotheincidencedirectionismuchmoreseverethanthatoftheoppositesideofcanyon.Andthegroundsurfacehasbeencharacterizedbylargerdeformationsinthecaseofobliqueincidentwaves.Itisalsoconcludedthatthelowpiersandframeofthecontinuousrigidframebridgearemoresensitivetothemulti-supportseismicexcitationsthantheflexiblehighpiers.Thecanyontopographyaswellastheobliqueincidenceofthewavesbringsthecontinuousrigidframebridgesevereresponses,whichshouldbetakenintoaccountinbridgedesign.
简介:Dynamicearthpressureinducedbymachinefoundationsonaneighboringretainingwallisanalyzedwithemphasisonfactorswhichcontroltheintensityandlocationofthedesignforces.ThemeshlesslocalPetrov-Galerkin(MLPG)methodisusedtoanalyzetheproblemforavarietyofretainingwallandmachinefoundationgeometries.Thesoilmediumisassumedtobehomogeneousandvisco-elastic.Themachinefoundationisidealizedasaharmonicsinusoidaldynamicforceoftenencounteredinpractice.Anumberofanalyseshavebeenmadetorevealtheeffectoftheloadingfrequency,thelocationandsizeofthefoundationandthesoilshearwavevelocityonthedistributionandmagnitudeofthedynamicearthpressure.Resultsindicatethatthereisacriticalfrequencyandacriticallocationforwhichthepassivepressuretakesthemaximaintheentiredurationofthedynamicload.