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简介:Whenoneendofanair-dryigneousrockblockwasuniaxiallyloadedinlaboratory,thereappearedanelectromotiveforcethatmadeelectriccurrentsflowfromthestressedvolumetotheunstressedvolume.Quartz-freerockssuchasgabbroalsogeneratedthisforce,strongerthanquartz-bearingrockssuchasgranite.Thisindicatesthatthepiezoelectriceffectofquartzandtheelectrokineticeffectofporewaterdonotmakealargecontributiontowardgeneratingtheelectromotiveforce.Wefocusonperoxybondthatisoneoftheabundantlatticedefectsinigneousrock-formingminerals.Whenmechanicalloadingdeformsthelatticestructurearoundthisdefectandbreaksitsbond,itsenergylevelschangeandactlikeanaccepter.AsanelectronistrappedatthisdefectfromaneighborO2-site,apositiveholeisactivatedthere.Theyattempttodiffusetowardtheunstressedvolumethroughthevalencebandandaresimultaneouslyaffectedbytheattractiveelectricforcewiththeelectronstrappedinperoxybonds.Thisleadstoapolarizationinthestressedvolumeandthegenerationofelectromotiveforcebetweenthestressedandunstressedvolumes.SimilarelectromotiveforcemaybegeneratedintheEarth’scrustwhereinhomogeneousstress/strainischanging.
简介:Amethodtocalculatethestationaryrandomresponseofanon-classicallydampedstructureisproposedthatfeaturesclearly-definedphysicalmeaningandsimpleexpression.Themethodisdevelopedinthetrequencydomain.Theexpressionoftheproposedmethodconsistsofthreeterms,i.e.,modalvelocityresponse,modaldisplacementresponse,andcoupled(betweenmodalvelocityandmodaldisplacementresponse).Numericalresultsfromtheparametricstudyandthreeexamplestructuresrevealthatthemodalvelocityresponsetermandthecoupledtermareimportanttostructuralresponseestimatesonlyforadynamicsystemwithatunedmassdamper.Intypicalcases,themodaldisplacementtermcanprovideresponseestimateswithsatisfactoryaccuracybyitself,sothatthemodalvelocitytermandcoupledtermmaybeignoredwithoutlossofaccuracy.Thisisusedtosimplifvtheresponsecomputationofnon-classicallydampedstructures.Forthewhitenoiseexcitation,threemodalcorrelationcoefficientsmclosedformarederived.Toconsiderthemodalvelocityresponsetermandthecoupledterm,asimplifiedapproximationbasedonwhitenoiseexcitationisdevelopedforthecasewhenthemodalvelocityresponseisimportanttothestructuralresponses.Numericalresultsshowthattheapproximateexpressionbasedonwhitenoiseexcitationcanprovidestructuralresponseswithsatisfactoryaccuracy.
简介:IntroductionThrough20-oddyears’observationandstudyafterthe1976Tangshangreatearthquake,theseismo-electromagneticradiationprec...
简介:Thisstudyinvestigatestheeffectivenessofthenon-smoothsemi-activecontrolalgorithmonsuppressingthevibrationperformanceofabuildingstructuresubjectedtoseismicwaves.AccordingtotheLyapunovstabilitytheory,ithasbeneproventhatthenon-smoothsemi-activecontrolalgorithmcanachieveafinite-timestabilityofthevibrationrelativetotheisolationlayerofabuildingstructure.Throughnumericalsimulationoftwobuildingswithdifferentparameterssubjectedtotheinputofaseismicwave,thevibrationconditionsofpassivecontrol,LQRsemi-activecontrolandnon-smoothsemiactivecontrolarecomparedandanalyzed.Thesimulationresultsshowthatthenon-smoothsemi-activecontrolalgorithmhasabetterrobustnessandeffectivenessinrestrainingtheimpactofearthquakesonthestructure.
简介:TherigidcentralbuckleemployedintheRunyangSuspensionBridge(RSB)wasthefirsttimeitwasusedinasuspensionbridgeinChina.ByusingaspectralrepresentationmethodandFFTtechniquecombinedwithmeasureddata,a3Dfluctuatingwindfieldconsideringthetowerwindeffectissimulated.AnovelFEmodelforbuffetinganalysisisthenpresented,inwhichaspecificuser-definedMatrix27elementinANSYSisemployedtosimulatetheaeroelasticforcesanditsstiffnessordampingmatricesareparameterizedbywindvelocityandvibrationfrequency.Anonlineartimehistoryanalysisiscarriedouttostudytheinfluenceoftherigidcentralbuckleonthewind-inducedbuffetingresponseofalong-spansuspensionbridge.Theresultscanbeusedasareferenceforwindresistancedesignoflong-spansuspensionbridgeswitharigidcentralbuckleinthefuture.
简介:增强的水泥(RC)框架结构是主要普通的使用的结构的系统之一,并且他们的地震表演被柱和横梁的表演大部分决定。这篇论文描述十列和三个横梁标本的水平周期的装载测试,其中一些根据当前的地震设计代码和其它被设计,根据早非地震的中国设计代码被设计,瞄准报导在Wenchuan地震期间观察的损坏或崩溃的RC框架strctures的行为。轴的负担比率的效果,砍跨度比率,和磁滞现象行为,韧性和损坏进步上的横向、纵的加强比率在试验性的学习被合并。测试结果显示non-seismically设计的列出现早熟砍失败,和收益更大的最大的剩余裂缝宽度和更多水泥spalling与地震联盟者设计列比。另外,纵的钢加强美国南北战争时南军士兵艺术严重地被弄弯。轴的负担比率并且砍证明是当纵的加强比率在柱韧性上有仅仅次要的效果,但是在横梁韧性上展出了更多的影响时,影响韧性,裂缝开始宽度和关门能力的最重要的因素的跨度比率。最后,横向的加强比率没影响最大的剩余裂缝宽度,地震联盟者的关门能力设计列。
简介:在在一个长期的服务时期上的好攻击的海洋的环境,沿海的桥不可避免地由于高海盐和湿度支撑导致腐蚀的损坏。这份报纸调查沿海的桥的力量减小,特别沿着桥墩的高度集中于不一致的腐蚀的效果。首先,腐蚀开始时间和加强和水泥的降级在海洋的环境为桥墩被分析。为了调查水泥的各种各样的损坏模式,盖住,有纤维房间的一个discretization方法在轴的力量和弯曲时刻的联合下面在大气的地区和潮汐的地区被用于桥墩的剖面图的精明的时间依赖者相互作用图。第二,这些变老的结构的shear力量被分析。数字模拟显示具体的墩的力量从腐蚀开始经历戏剧的减小到具体盖子的spalling。在骚动和潮汐的地区的力量损失比在大气的地区什么时候组织服务时间,被假定是一样的是更重要的。
简介:Thenon-tidalvariationgainedfromcontinuousgravityobservationsinstationsusuallyreflectstheregionalcontinuousgravitychanges.Inthispaperwefocusonstudyingthenon-tidalvariationofBaijiatuanstation,Beijingwheretherearetwodifferentgravimeters(namely,L&R-804andPET-031).Basedontheoriginalrawtidalrecordsoftwogravimetersfrom2008to2011,wefirstremovevariousinterferencefromrawdatabythestandardproceduresoftware-Tsoft;thenwemodelthesolidearthtides,oceantidalloadingandpoletidethroughrelatedparameters;afterthatweadoptanewsegmentedpolynomialfittingmethodbasedonTsofttofitthecomplexdriftofspringgravimeter;andfinallywecalculatetheatmosphericloadingeffectsbyalinearregressionmodel.Afteraseriesofprocessingwegainthenon-tidalvariationofthetwogravimetersatBaijiatuansite,Beijing.Furthermore,toanalyzethenon-tidalvariationpreliminarily,westudythemaincomponentofrelatedtidaldatabypowerspectraldensity.Comparingthenon-tidalvariationoftwodifferentgravimeters,wefindseasonalfluctuationsinnon-tidalresults,whichareinaccordancewiththewaterstoragechange.Therefore,wetakeintoaccounttherelevanceofgravitychangesandwaterstoragebasedonthegravitydataofGRACEandwaterdataoftheCMAPmodelfrom2003to2011atdifferentsitesintheChinesemainland(Beijing,Chengdu,ShenyangandShiquanhe),andmakeapreliminaryanalysisontherelationshipbetweengravitychangesandwaterstorage.
简介:Basedonthemodelsofnon-uniformearthquakedistributioninthepotentialsource,theseismiczonationofWesternPanzhihuaandCentralandSouthernShanxiProvinceisstudied.Theresultsshowthattheusualuniformdistributionmodelmayunderestimatetheseismicriskandresultinareductionoftheareasofhighintensity.Theinfluenceofeachnon-uniformprobabilisticdistributionmethodontheresultofseismiczoningisdiscussed.