土木工程钢结构和钢筋混凝土结构外文文献翻译.docx
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土木工程钢结构和钢筋混凝土结构外文文献翻译
文献信息:
文献标题:
Recentresearchanddesigndevelopmentsinsteelandcompositesteel–concretestructuresinUSA(近期美国在钢结构和钢筋混凝土结构研究和设计方面的发展)
国外作者:
TheodoreV.Galambos
文献出处:
《JournalofConstructionalSteelResearch》,2000,55(1-3):
289-303
字数统计:
英文4718单词,23395字符;中文7671汉字
外文文献:
Recentresearchanddesigndevelopmentsinsteelandcompositesteel–concretestructuresinUSA
AbstractAbriefreviewofthestatusofstructuralsteelresearchintheUSattheendoftheTwentiethCenturyispresentedinthispapertoshowthatwhilemanyproblemsarebeingsolved,therearenewandchallengingproblemsremaining.Thechiefimpetusforcontinuedresearchisthatprovidedbynaturaldisasters,suchasearthquakes,tropicalstorms,tornadoesandfloodsoccurringindenselypopulatedurbanareas.Newmaterialsandnewexperimentalandcomputationaltechnologiesalsogiverisetonewandexcitingresearchproblems.
Keywords:
Bridges;Buildings;Design;Research;Steelstructures;UnitedStatesofAmerica;Seismicbehavior;High-performancematerials
1.Introduction
ThepurposeofthispaperistogiveabriefoverviewofthecurrentdevelopmentsinstructuralsteelresearchintheUS,andofthefuturedirectionsthatthestructuralsteelengineeringresearchmaytakeinthecomingCentury.Thedrivingforcesofresearchinthisfieldarethefollowing:
•newconstructionmethodsandconstructionproducts
•newmaterials
•economicconsiderations
•naturaldisasters
Threeofthesemotivationsarecommontoallengineeringdevelopments,notjusttostructuralengineering.However,theimpetusduetonaturaldisastersisuniquetoourfield.RecentmajornaturaldisastersintheUS,suchastheNorthridgeearthquakeinCaliforniaandhurricaneAndrewinFlorida,havespurredmuchofthecurrentresearchactivity.
Thepresentationhereisofnecessityincomplete,becausetheauthorisnotawareofallresearchgoingoneverywhereinthecountryandthereisnotenoughspaceinthispresentation.Theoverviewismeanttogiveageneralflavoroftheresearchactivities,andtoshowthatasignificanteffortisgoingonintheUS.Thefollowingisalistof10majortopicsinsteelresearch:
1.LimitStatesDesignforbridges
2.Monitoringofstructuralperformanceinthefield
3.Designofseismicallyresistantconnections
4.Curvedgirderbridges
5.Compositecolumnswithhigh-performanceconcrete
6.Buildingframeswithsemi-rigidjoints
7.“AdvancedStructuralAnalysis”forbuildings
8.Repairandretrofitofstructures
9.Steelstructureswithhigh-performancesteels
10.Cold-formedsteelstructures
Thenextpartsofthispaperwillgivebriefdiscussionsonsomeofthesetopics.Severaltopicswillthenbeelaboratedinmoredetail.Thepaperwillconcludewithalooktowardthefutureofstructuralsteelresearch.
2.Researchonsteelbridges
TheAmericanAssociationofStateTransportationandHighwayOfficials(AASHTO)istheauthoritythatpromulgatesdesignstandardsforbridgesintheUS.In1994ithasissuedanewdesignspecificationwhichisaLimitStatesDesignstandardthatisbasedontheprinciplesofreliabilitytheory.Agreatdealofworkwentintothedevelopmentofthiscodeinthepastdecade,especiallyoncalibrationandontheprobabilisticevaluationofthepreviousspecification.Thecodeisnowbeingimplementedinthedesignoffice,togetherwiththeintroductionoftheSystemeInternationaleunits.Manyquestionsremainopenaboutthenewmethodofdesign,andtherearemanynewprojectsthatdealwiththereliabilitystudiesofthebridgeasasystem.Onesuchcurrentprojectisastudytodevelopprobabilisticmodels,loadfactors,andrationalload-combinationrulesforthecombinedeffectsofliveloadandwind;live-loadandearthquake;live-load,windandshipcollision;andshipcollision,wind,andscour.Therearealsomanyfieldmeasurementsofbridgebehavior,usingmoderntoolsofinspectionandmonitoringsuchasacousticemissiontechniquesandothermeansofnon-destructiveevaluation.Suchfieldworknecessitatesparallelstudiesinthelaboratory,andtheevolutionofevermoresophisticatedhigh-technologydatatransmissionmethods.
Americahasanagingsteelbridgepopulationandmanyproblemsarisefromfatigueandcorrosion.Fatiguestudiesonfull-scalecomponentsoftheWilliamsburgBridgeinNewYorkhaverecentlybeencompletedatLehighUniversity.AprobabilisticAASHTObridgeevaluationregulationhasbeenineffectsince1989,anditisemployedtoassessthefutureusefullifeofstructuresusingrationalmethodsthatincludefieldobservationandmeasurementtogetherwithprobabilisticanalysis.Suchanactivityalsofostersadditionalresearchbecausemanyissuesarestillunresolved.Onesuchareaisthestudyoftheshakedownofshearconnectorsincompositebridges.ThisworkhasbeenrecentlycompletedattheUniversityofMissouri.
Inadditiontofatigueandcorrosion,themajordangertobridgesisthepossibilityofearthquakeinduceddamage.Thisalsohasspawnedmanyresearchprojectsontherepairandretrofitofsteelsuperstructuresandthesupportingconcretepiers.Manybridgesinthecountryarebeingstrengthenedforearthquakeresistance.Oneareathatisreceivingmuchresearchattentionisthestrengtheningofconcretepiersby“jacketing”thembysheetsofhigh-performancereinforcedplastic.
Thepreviouslydescribedresearchdealsmainlywiththebehaviorofexistingstructuresandthedesignofnewbridges.However,thereisalsoavigorousactivityonnovelbridgesystems.Thisresearchiscenteredontheapplicationofhigh-performancesteelsforthedesignofinnovativeplateandbox-girderbridges,suchascorrugatedwebs,combinationsofopenandclosedshapes,andlongerspansfortrussbridges.Itshouldbementionedherethat,inadditiontoworkonsteelbridges,thereisalsoveryactiveresearchgoingoninthestudyofthebehaviorofprestressedconcretegirdersmadefromveryhighstrengthconcrete.Theperformanceanddesignofsmallerbridgesusingpultrudedhigh-performanceplasticcompositemembersisalsobeingstudiedextensivelyatpresent.Newcontinuousbridgesystemswithsteelconcretecompositesegmentsinboththepositivemomentandthenegativemomentregionsarebeingconsidered.Severalresearchershavedevelopedstrongcapabilitiestomodelthethree-dimensionalnon-linearbehaviorofindividualplategirders,andmanystudiesarebeingperformedonthebucklingandpost-bucklingcharacteristicsofsuchstructures.Companionexperimentalstudiesarealsomade,especiallyonmembersbuiltfromhigh-performancesteels.Afull-scalebridgeofsuchsteelhasbeendesigned,andwillsoonbeconstructedandthentestedundertrafficloading.Researcheffortsarealsounderwayonthestudyofthefatigueoflargeexpansionjointelementsandonthefatigueofhighwaysignstructures.
Thefinalsubjecttobementionedistheresurgenceofstudiesofcompositesteelconcretehorizontallycurvedsteelgirderbridges.AjustcompletedprojectattheUniversityofMinnesotamonitoredthestressesandthedeflectionsinaskewedandcurvedbridgeduringallphasesofconstruction,startingfromthefabricationyardtothecompletedbridge.Excellentcorrelationwasfoundtoexistbetweenthemeasuredstressesanddeformationsandthecalculatedvalues.Thestressesanddeflectionsduringconstructionwerefoundtoberelativelysmall,thatis,theconstructionprocessdidnotcauseseveretraumatothesystem.Thebridgehasnowbeentestedunderserviceloading,usingfullyloadedgraveltrucks,fortwoyears,anditwillcontinuetobestudiedforfurtheryearstomeasurechangesinperformanceunderserviceovertime.AmajortestingprojectisbeingconductedattheFederalHighwayAdministrationlaboratoryinWashington,DC,whereahalf-scalecurvedcompositegirderbridgeiscurrentlybeingtestedtodetermineitslimitstates.Thetest-bridgewasdesignedtoactasitsowntest-frame,wherevariousportionscanbereplacedaftertesting.Multipleflexuretests,sheartests,andtestsundercombinedbendingandshear,arethusperformedwithrealisticend-conditionsandrestraints.Theexperimentsarealsomodeledbyfiniteelementanalysistocheckconformancebetweenrealityandprediction.Finallydesignstandardswillbeevolvedfromtheknowledgegained.ThislastprojectisthelargestbridgeresearchprojectintheUSAatthepresenttime.
Fromthediscussionaboveitcanbeseenthateventhoughthereisnolargeexpansionofthenation’shighwayandrailroadsystem,thereisextensiveworkgoingoninbridgeresearch.Themajorchallengefacingboththeresearcherandthetransportationengineeristhemaintenanceofahealthybutagingsystem,seeingtoitsgradualreplacementwhilekeepingitsafeandserviceable.
3.Researchonsteelmembersandframes
Therearemanyresearchstudiesonthestrengthandbehaviorofsteelbuildingstructures.Themostimportantofthesehavetodowiththebehavioranddesignofsteelstructuresundersevereseismicevents.Thistopicwillbediscussedlaterinthispaper.Themostsignificanttrendsofthenon-seismicresearcharethefollowing:
•“Advanced”methodsofstructuralanalysisanddesignareactivelystudiedatmanyUniversities,notablyatCornell,Purdue,Stanford,andGeorgiaTechUniversities.Suchanalysismethodsaremeanttodeterminetheload-deformationbehaviorofframesuptoandbeyondfailure,includinginelasticbehavior,forceredistribution,plastichingeformation,second-ordereffectsandframeinstability.Whenthesemethodsarefullyoperational,thestructurewillnothavetoundergoamembercheck,becausethefiniteelementanalysisoftheframeautomaticallyperformsthisjob.Inadditiontotheres