外文翻译通过建筑结构设计以改善建筑物的抗倒性.docx
- 文档编号:3762239
- 上传时间:2022-11-25
- 格式:DOCX
- 页数:11
- 大小:191.05KB
外文翻译通过建筑结构设计以改善建筑物的抗倒性.docx
《外文翻译通过建筑结构设计以改善建筑物的抗倒性.docx》由会员分享,可在线阅读,更多相关《外文翻译通过建筑结构设计以改善建筑物的抗倒性.docx(11页珍藏版)》请在冰豆网上搜索。
外文翻译通过建筑结构设计以改善建筑物的抗倒性
外文原稿2
TheTwelfthEastAsia-PacificConferenceonStructuralEngineeringandConstruction
DesignofBuildingStructurestoImprovetheirResistance
toProgressiveCollapse
DANethercota
aDepartmentofCivilandEnvironmentalEngineering,ImperialCollegeLondon
Abstract:
Itisrarenowadaysfora“newtopic”toemergewithintherelativelymaturefieldofStructuralEngineering.Progressivecollapse-or,moreparticularly,understandingthemechanicsofthephenomenonanddevelopingsuitablewaystoaccommodateitsconsiderationwithinournormalframeworksforstructuraldesign-canbesoregarded.BeginningwithillustrationsdrawnfromaroundtheworldoverseveraldecadesandculminatinginthehighlypublicWTCcollapses,thosefeaturesessentialforarepresentativetreatmentareidentifiedandearlydesignapproachesarereviewed.Morerecentworkisthenreported,concentratingondevelopmentsofthepastsevenyearsatImperialCollegeLondon,whereacomprehensiveapproachcapableofbeingimplementedonavarietyoflevelsandsuitablefordirectusebydesignershasbeenunderdevelopment.Illustrativeresultsareusedtoassistinidentifyingsomeofthekeygoverningfeatures,toshowhowquantitativecomparisonsbetweendifferentarrangementsmaynowbemadeandtoillustratetheinappropriatenessofsomepreviousdesignconceptsasawayofdirectlyimprovingresistancetoprogressivecollapse.
2011PublishedbyElsevierLtd.
Keywords:
Compositestructures;ProgressiveCollapse;Robustness;Steelstructures;Structuraldesign
1.Introduction
Overtimevariousdifferentstructuraldesignphilosophieshavebeenproposed,theirevolutionarynaturereflecting:
*Growingconcerntoensureadequateperformance.
*Improvedscientificknowledgeofbehaviour.
*Enhancedabilitytomovefromcraftbasedtosciencebasedandthusfromprescriptivetoquantitativelyjustifiedapproaches
Thiscanbetracedthroughconceptssuchas:
permissiblestress,ultimatestrength,limitstatesandperformancebased.Asclients,usersandthegeneralpublichavebecomeincreasinglysophisticatedandthusmoredemandingintheirexpectations,soitbecamenecessaryfordesignerstocoveraneverincreasingnumberandrangeofstructuralissues–mostlythroughconsiderationofthe“reachingthisconditionwouldbetoagreaterorlesserextentunacceptable”approach.Thereforeissuesnotpreviouslyconsidered(oronlyallowedforinanimplicit,essentiallycopyingpastsatisfactoryperformance,way)startedtorequireexplicitattentionintheformof:
anassessmentofdemand,modellingbehaviourandidentificationofsuitablefailurecriteria.Thetreatmentoftopicssuchasfatigue,fireresistance,durabilityandserviceabilitycanallbeseentohavefollowedthispattern.
Totakeaspecificexample:
designingadequatefireresistanceintosteelframedbuildingsbegan(oncetheneedhadbeenrecognised)withsimpleprescriptiverulesforconcreteencasementofvulnerablemembersbutithas,inrecentyears,evolvedintoasophisticateddisciplineoffireengineering,concernedwithfireloading,theprovisionofprotectivesystemssuchassprinklers,calculationofresponseintheeventofafireandtheabilitytomakequantitativecomparisonsbetweenalternativestructuralarrangements.Notonlyhasthisledtoobviouseconomicbenefitsinthesenseofnotprovidingfireprotectionwhereitgaveonlynegligiblebenefit,ithasalsoledtoincreasedfiresafetythroughbetterunderstandingofthegoverningprinciplesandtheabilitytoactintelligentlyindesigningsuitablearrangementsbasedonaproperassessmentofneed.
PriortotheRonanPointcollapseinLondonin1968thetermsrobustness,progressivecollapse,
disproportionatecollapseetc.,werenotpartofStructuralEngineeringvocabulary.Theconsequencesofthedamagedonetothat22storeyblockofpre-castconcreteapartmentsbyaverymodestgasexplosiononthe18thfloorledtonewprovisionsintheUKBuildingRegulations,outlawingformanyyearsofsocalledsystembuiltschemes,demolitionofseveralcompletedbuildings,temporaryremovalofgasinhighriseconstructionandtheformationoftheStandingCommitteeonStructuralSafety.Eventually,thebenefitsofproperlyengineeredpre-fabricationwererecognised,safemethodsfortheinstallationofgasweredevisedandtheindustrymovedon.However,thestructuraldesignguidanceproducedatthattime-thatstillunderpinsmuchpresentdayprovision-wasessentiallyprescriptiveinnaturewithnoreallinktoactualperformance.
SubsequentincidencesofprogressivecollapsesuchastheMurraghBuildingandtheWorldTradeCentrebroughtincreasedattentiontotheactualphenomenonandissuesofhowitmightreasonablybetakenintoaccountforthosestructuraldesignswhereitwasconsideredappropriate.Indoingthisitis,ofcourse,essentialtoincludeboththeriskofatriggeringincidentandtheconsequencesofafailuresothattheresultingmoreonerousstructuraldemandsareusedappropriately.Arguably,adisproportionateresponseintermsofrequiringcostlyadditionalprovisionsincaseswheretherisks/consequencesareverylow/veryminormaybeasharmfulasfailingtoaddressthosecaseswheretherisks/consequencesarehigh/severe.
ThispaperwillreviewcurrentapproachestodesigntoresistprogressivecollapseandcontrastthesewithworkundertakenoverthepastsevenyearsatImperialCollegeLondon,wherethegoalhasbeentheprovisionofarealisticallybasedmethodsuitableforuseinroutinedesign.Theessentialfeaturesofthemethodwillbepresented,itsuseonseveralexamplesdescribedandresultspresentedtoillustratehowitisleadingtoabetterunderstandingofboththemechanicsofprogressivecollapseandthewaysinwhichstructuralengineerscanbestconfiguretheirstructuressoastoprovideenhancedresistance
2.Designtoresistprogressivecollapse
Thetwomostfrequentlyuseddesignapproachesintendedtoaddresstheissueofprogressivecollapseare:
*Providingtyingcapacity
*Checkingalternateloadpaths
Figure1:
TieForcesinaFrameStructure
Thefirstisessentiallyprescriptiveandconsistsofensuringthatbeams,columns,connectionsandfloor(orroof)canacttogethertoprovideaspecifiedminimumlevelofhorizontaltyingresistance;theactualvaluesrequiredarenormallyrelatedtotheverticalloading.Figure1,whichistakenfromrecentUSGuidance(SEI2010),illustratestheprinciple.Theapproachissimpletoappreciate,requiresminimalstructuralcalculationand,insituationswheretheoriginalprovisionsarefoundtobeinadequate,canbemadetoworkbyprovidingmoresubstantialconnectionsand/oradditionalreinforcementinfloorslabsInaninterestingrecentdevelopment,thatrecognizesthelinktothegenerationofcatenaryaction,USGuidancehasrestrictedtheuseoftyingbetweenthestructuralmemberstosituationsinwhichitcanbedemonstratedthattheassociatedconnectionscancarrytherequiredforceswhilstundergoingrotationsof0.2radiance.Wherethisisnotpossible,tyingshouldactthroughthefloorsandtheroof.However,recentstudies(Nethercotetal2010a;Nethercotetal2010b)havesuggestedthattyingcapacitycorrelatespoorlywithactualresistancetoprogressivecollapse.Moreover,beingprescriptive,itdoesnotpermitthemeaningfulcomparisonofalternativearrangements-afundamentalfeatureofstructuraldesign.
Initsmostfrequentlyusedformthealternativeloadpathapproachpresumestheinstantaneouslossofasinglecolumnandthenrequiresthattheabilityoftheresultingdamagedstructuretobridgethelossbedemonstratedbysuitablecalculation(GudmundssonandIzzuddin2010).Theapproachmaybeimplementedatvaryinglevelsofsophisticationintermsoftheanalysis;forexample,recentthinkingintheUnitedStates(SEI2010)makesprovisionforanyof:
linearstatic,non-linearstaticornon-lineardynamicanalysisandprovidessomeguidanceontheuseofeach.Itmayalsobeusedasthebasisformoresophisticatednumericalstudiesofparticularstructuresandparticularincidentse.g.forensicwork;thebestofthese–whicharelikelytobecomputationallyverydemanding–havedemonstratedtheirabilitytocloselyreplicateactualobservedbehaviour.
3.Essentialfeaturesofprogressivecollapse
Threefeatureshavepreviously(Nethercot2010)beingidentifiedasessentialcomponentsofanyreasonablyrealisticapproachtodesignagainstprogressivecollapse:
*Eventstakeplaceoveraveryshorttimescaleandtheactualfailureisthereforedynamic.
*Itinvolvesgrossdeformations,generatinglargestrains,leadingtoinelasticbehaviouraswellaschangeofgeometryeffects.
*Failureessentiallycorrespondstoaninabilityofthestructureinitsdamagedstatetoadoptanewpositionofequilibriumwithoutseparationofkeyelements.
Figure2:
Simplifiedmulti-levelapproachforprogressivecollapseassessment
Additionalfeatures,designedtomaketheapproachattractiveforusebypracticingEngineershavealsobeenproposed(Nethercot2010):
*Processshouldconsistofaseriesofstepsbroadlysimilarinconcepttothoseusedfor“conventional”structuraldesign.
*Itshould,preferably,becapableofimplementationatavarietyatlevelsofcomplexity–withthechoicereflectingtheimportanceofthestructure.
*Anyrequiredanalysisshouldutilisefamiliartechniques;wheretheserequirecomputationsbeyond“handmethods”,theseshouldbebasedontheuseofavailableanalysissoftware.
*Arealisticandrecognisablecriterionoffailureshouldbeused.
*Approachshouldpermitstudyofcauseandeffectandbesuitableforthemaking
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- 外文 翻译 通过 建筑结构 设计 改善 建筑物 抗倒性
![提示](https://static.bdocx.com/images/bang_tan.gif)