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30 个结果
  • 简介:Ahybridanalysismethodintimeandfrequencydomainsforlinearsoil-structureinteractionispresented.First,thetimedomainsolutionofthesystemwithRayleighdampingexcitedbyashorttimeimpulseisobtainedbythedecouplingnumericalsimulationtechniqueofnear-fieldwavemotion.Then,thecorrespondingfrequencydomainsolutioncanbegotbyFouriertransform.Accordingtotherelationshipbetweendampingvalueanddynamicre-sponseofasystem,thesolutionofthesystemwithcomplexdampingcanbegotbyTaylorexpansion.Thehybridmethodmakesthebestofdecouplingandexplicitalgorithmintimedomain,andincreasesthecalculationefficien-cyforlinearsoil-structureinteractionanalysis.

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  • 简介:一个方法被建议在设计实践为使用估计地震soil-structure-interaction(SSI)效果。它对受到的2D结构适用垂直地事件砍波浪由同质的一半空间支持了。自从它保留简洁,方法是吸引人的光谱途径,克服一些困难和存在古典技术的不确,然而,它考虑身体上一致的刺激。简洁的这水平通过回答被完成能被用于免费地的5%阻尼反应系列产出设计的系列修正因素光谱考虑散布运动的纵标由相互作用效果介绍了。修正因素在结构的相对排水量和免费地的运动之间的转移功能(TF)是代表性的,它以它的最大的振幅被描述并且联系了频率。由练习工程师计算修正因素的表情被建议用实际结构的576盒子代表在参量的研究之上基于。方法在跨越大量普通基本颤动时期的10种情况中被测试。

  • 标签: 土-结构相互作用 二维模型 地震 程序 修正系数 工程实践
  • 简介:PastresearchershaveanticipatedtheoccurrenceofagreatearthquakeinthecentralHimalayasinthenearfuture.ThismaycauseseriousdamageintheKathmanduValley,whichsitsonanancientlakebedzone,withlacustrinesedimentsofmorethan500mdepth.Inthisstudy,thepredominantfrequencyofgroundmotionisevaluatedusingtheHorizontal-to-Vertical(H/V)spectralratiotechniqueandrecordingsofambientnoise.TheresultsoftheH/Vratioshowtwopeaksinabout20percentofthelocations,whicharedistributedmainlyinandaroundthecenterandnorthernpartoftheKathmanduValley.Thepredominantfrequenciesvaryfrom0.5Hzto8.9Hzinthestudyarea,whereasthesecondresonancefrequencyvariesfrom4Hzto6Hzinthecenterandnorthernpartofthevalley.Thisindicatesthatthecenterandnorthernpartofthevalleyhaveawiderangeofresonancefrequencyduetotwolevelsofimpedancecontrastonemaybefromthesurfacelayerandtheothermaybefromthelayerunderneath.ThesetwolevelsofresonanceindicatetheimportanceofconsideringtheeffectsofsurfaceandlowerlayersduringtheplanninganddesigningofinfrastructuresintheKathmanduValley.

  • 标签: MICROTREMOR predominant FREQUENCY RESONANCE Kathmandu VALLEY
  • 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.

  • 标签: 阻抗函数 模型试验 粘性土 三维非线性有限元分析 单桩 数值分析
  • 简介:TodeterminetheshearwavevelocitystructureandpredominantperiodfeaturesofT?naztepein?zmir,Turkey,wherenewbuildingsiteshavebeenplanned,active–passivesurfacewavemethodsandsingle-stationmicrotremormeasurementsareused,aswellassurfaceacquisitiontechniques,includingthemultichannelanalysisofsurfacewaves(MASW),refractionmicrotremor(ReMi),andthespatialautocorrelationmethod(SPAC),topinpointshallowanddeepshearwavevelocity.Forengineeringbedrock(V_s>760m/s)conditionsatadepthof30m,anaverageseismicshearwavevelocityintheupper30mofsoil(AV_s30)isnotonlyacceptedasanimportantparameterfordefininggroundbehaviorduringearthquakes,butaprimaryparameterinthegeotechnicalanalysisforareastobeclassifiedbyV_s30accordingtotheNationalEarthquakeHazardsReductionProgram(NEHRP).ItisalsodeterminedthatZ1.0,whichrepresentsadepthtoV_s=1000m/s,isusedforgroundmotionpredictionandchangedfrom0to54m.Thesediment–engineeringbedrockstructureforT?naztepethatwasobtainedshowsengineeringbedrocknodeeperthan30m.Whencompared,thedepthofengineeringbedrockanddominantperiodmapandgeologyaregenerallycompatible.

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  • 简介:Ashake-tableexperimentonpilefoundationsinliquefiablesoilscomposedofliquefiablesandandoverlyingsoftclayisstudied.Athree-dimensional(3D)effectivestressfiniteelement(FE)analysisisemployedtosimulatetheexperiment.Arecentlydevelopedmulti-surfaceelasto-plasticconstitutivemodelandafullycoupleddynamicinelasticFEformulation(u-p)areusedtomodeltheliquefactionbehaviorofthesand.Thesoildomainsarediscretizedusingasolid-fluidfullycoupled(u-p)20-8nodedbrickelement.Thepileissimulatedusingbeam-columnelements.Uponcarefulcalibration,verygoodagreementisobtainedbetweenthecomputedandthemeasureddynamicbehaviorofthegroundandthepile.Aparametricanalysisisalsoconductedonthemodeltoinvestigatetheeffectofpile-pinning,pilediameter,pilestiffness,groundinclinationangle,superstructuremassandpileheadrestraintsonthegroundimprovement.Itisfoundthatthepilefoundationhasanoticeablepinningeffectthatreducesthelateralsoildisplacement.Itisobservedthatalargerpilediameterandfixedpileheadrestraintscontributetodecreasingthelateralpiledeformation;however,ahighergroundinclinationangletendstoincreasethelateralpileheaddisplacementsandpilestiffness,andsuperstructuremassseemstoeffectivelyinfluencethelateralpiledisplacements.

  • 标签: LIQUEFACTION PILE PINNING soil improvement PILE
  • 简介:Itisknownthatstructuralstiffnessandstrengthdistributionshaveanimportantroleintheseismicresponseofbuildings.Theeffectofusingdifferentcode-specifiedlateralloadpatternsontheseismicperformanceoffixed-basebuildingshasbeeninvestigatedbyresearchersduringthepasttwodecades.However,noinvestigationhasyetbeencarriedoutforthecaseofsoil-structuresystems.Inthepresentstudy,throughintensiveparametricanalysesof21,600linearandnonlinearMDOFsystemsandconsideringfivedifferentshearstrengthandstiffnessdistributionpatterns,includingthreecode-specifiedpatternsaswellasuniformandconcentricpatternssubjectedtoagroupofearthquakesrecordedonalluviumandsoftsoils,theeffectofstructuralcharacteristicsdistributiononthestrengthdemandandductilityreductionfactorofMDOFfixed-baseandsoil-structuresystemsareparametricallyinvestigated.Theresultsofthisstudyshowthatdependingonthelevelofinelasticity,soilflexibilityandnumberofdegrees-of-freedoms(DOFs),structuralcharacteristicsdistributioncansignificantlyaffectthestrengthdemandandductilityreductionfactorofMDOFsystems.Itisalsofoundthatathighlevelsofinelasticity,theductilityreductionfactoroflow-riseMDOFsoil-structuresystemscouldbesignificantlylessthanthatoffixed-basestructuresandthereductionislesspronouncedasthenumberofstoriesincreases.

  • 标签: soil-structure interaction MDOF systems structural characteristic
  • 简介:扭曲的桥的地震行为很好没与直桥相比被学习。扭曲的桥显示出广泛的损坏,特别由于甲板旋转,砍钥匙失败,桥墩剥夺和列偏好漂流。因此,这研究试图学习行为扭曲并且直高速公路天桥有或没有由于近差错的地面运动考虑土壤结构相互作用(SSI)的效果衔接两个。由于与扎根的运动,土壤和结构联系的无常的几来源,一条概率的途径被需要。因此,类似于那的概率的方法论由和平的地震工程研究中心(同伴)发展了被利用了由于与最小的分散用适当紧张措施摇晃的各种各样的层次估计损坏的概率。概率的分析为各种各样的桥配置和地点条件被执行,包括沙从对松开稠密并且泥土从对软生硬,以便评估效果。结果证明了扭曲的桥的可观的危险性到甲板旋转并且砍钥匙排水量。没有包括SSI,SSI与改正底模型相比为各种各样的要求在损坏概率上有减少的效果,这也被发现。然而,为所有的甲板旋转土壤并且也打剥夺的桥墩因为很松开的沙和软泥土与改正底模型相比在损坏概率显示出增加。为各种各样的要求的损坏概率也被发现了为沙、粘土似的地点随土壤力量的增加减少。关于在斜角度的变化,斜角度的增加为各种各样的要求在地震反应的振幅上有增加的效果。甲板旋转对斜角度的增加很敏感;因此,当斜角度增加了,甲板旋转因此反应了。而且,桥墩剥夺为改正底和SSI模型由于斜角度的增加显示出一个增加的趋势。

  • 标签: 土-结构相互作用 抗震性能 性能评价 斜梁桥 场地 概率分析
  • 简介:象lumped参数模型那样的分离模型和有限元素模型广泛地在地震的土壤扩大的解决方案被使用。然而,任何一个模型都精确地不估计土壤沉积物的自然频率,也不模仿一抑制频率独立。这研究基于模式等价方法为分层的土壤沉积物的一个维的粘弹性的反应分析开发一个新分离模型。新分离模型是一系列集中的群众,弹簧和缓冲筒与一种特殊配置描绘的一个一个维的相等的multi-degree-of-freedom(MDOF)系统。相等的MDOF系统的动态反应是导出的经分解,物理参数以形式的性质被提出。相等的MDOF系统与可得到的理论解决方案通过扩大函数的比较被验证。在相等的MDOF系统的自由(DOF)的度的适当数字被估计。有存在的相等的MDOF系统的比较研究分离模型被执行。建议相等的MDOF系统罐头确切介绍土壤存款抑制的自然频率和hysteretic并且向更精确的结果提供更少DOF,这被显示出。

  • 标签: 土壤沉积物 反应分析 粘弹性 相等 系统 MDOF
  • 简介:性能基于设计为估计大楼的地震要求成为一个有效方法。在不对称的计划高大楼更高的模式和扭转的效果是关键的。连续形式的闲差事(CMP)过程是过程之一考虑这些效果。另外,在以前的研究,在闲差事分析的土壤结构相互作用(SSI)的影响被忽略。在这份报纸,CMP过程就SSI而言为中间的单程的不对称的计划和高楼大楼被修改。扩大CMP(ECMP)过程被建议以便克服CMP过程的一些限制。在这方面,有不对称的计划的10,15和20座故事大楼就假定三个不同土壤条件的SSI而言被学习。用在一套双向地面运动下面的非线性的反应历史分析;这些大楼的准确回答是计算的。然后,ECMP过程被把这个过程的结果与历史作为一个准确答案以及形式的闲差事分析过程和FEMA356负担模式结果的非线性的时间作比较评估。结果表明ECMP过程的精确性。

  • 标签: PUSHOVER分析 土-结构相互作用 高阶模态 高层建筑 非对称式 地震响应