最新土木工程英语翻译英汉.docx
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最新土木工程英语翻译英汉.docx
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最新土木工程英语翻译英汉
Human-StructureDynamicInteractioninCivil
EngineeringDynamics:
ALiteratureReview
ABSTRACT
Thispaperreviewsmorethan130piecesofessentialliteraturepertinenttotheproblemofhuman-structuredynamicinteractionapplicabletothedesignofcivilengineeringstructures.Thisinteractiontypicallyoccursinslenderstructuresoccupiedanddynamicallyexcitedbyhumansbywalking,running,jumpingandsimilaractivities.Thepaperfirstlyreviewstheliteraturedealingwiththeeffectsofstructuralmovementonhuman-induceddynamicforces.Thisisthefirstoftwoaspectsofhuman-structuredynamicinteraction.Theliteraturedealingwiththisaspectisfoundtobequitelimited,butconclusiveinstatingthatstructuralmovementcanaffectthehuman-induceddynamicforces–significantlyinsomecases.Thesecondaspectconsideredishowhumanoccupantsinfluencethedynamicproperties(mass,stiffnessanddamping)ofthestructurestheyoccupy.Thebodyofliteraturedealingwiththisissueisfoundtobeconsiderablylarger.Thepublishedliteraturedemonstratesbeyondanydoubtthathumanspresentonstructuresshouldnotbemodeledjustasadditionalmass,whichisacommonapproachincontemporarycivilengineeringdesign.Instead,humanspresentonstructuresactasdynamicspring-mass-dampersystemsinteractingwiththestructuretheyoccupy.Thelevelofthisinteractionisdifficulttopredictanddependsonmanyfactors,includingthenaturalfrequencyoftheemptystructure,thepostureandtypeofhumanactivity,andinthecaseofassemblystructures,relativesizeofthecrowdcomparedwiththesizeofthestructure.Oneofthereasonsfortheexistenceofmorepapersinthisareaisthepublishedbiodynamicalresearchintothemass-spring-damperpropertiesofhumanbodiesapplicabletothemechanicalandaerospaceengineeringdisciplines.Itshouldbestressedthatresultsfromthisresearchareoflimitedvaluetocivilengineeringapplications.Thisisbecausehumanbodiesare,inprinciple,non-linearwithamplitude-dependentdynamicproperties.Levelsofvibrationwhenexperimentallydeterminingmass-spring-damperpropertiesofhumanbodiesinbiodynamicalresearchareusuallyconsiderablyhigherthanthoseexperiencedincivilengineeringapplications.
KEYWORDS
literaturereview,human-structureinteraction,dynamicoccupantmodels,civilengineering
1.INTRODUCTION
Incivilengineeringdynamics,human-inducedvibrationsareanincreasinglyimportantserviceabilityandsafetyissue.Inrecentyears,therehasbeenanincreasingnumberofproblemsrelatedtohuman-inducedvibrationsoffloors,footbridges,assemblystructuresandstairs.Human-structureinteractionisanimportantbutrelativelynewconsiderationwhendesigningslenderstructuresoccupiedanddynamicallyexcitedbyhumans(EllisandJi,1997).
Human-structureinteractionisacomplex,inter-disciplinaryandlittleresearchedissue.Tosummariestheexistingknowledge,thispaperreviewstwokeyareasofhuman-structureinteraction:
(1)howstructuralvibrationscaninfluenceforcesinducedbyhumanoccupants
(2)howhumanoccupantsinfluencethedynamicpropertiesofcivilengineeringstructures
Focusingmoreonthelatterissueandlimitingittopassivesittingorstandingpeople,biomechanicsresearchandmodelsofthehumanwhole-bodyarethenreviewed(section4).Furthermore,investigationsanalyzingandmodelinghumanoccupantsoncivilengineeringstructuresarepresented(section5).Next,researchintothepotentialofhumanoccupantstoabsorbvibrationenergyisreviewedand,finally,conclusionsarepresented
2.EFFECTSOFHUMAN-STRUCTUREINTERACTIONONHUMAN-INDUCEDFORCES
Humanoccupantscaninducedynamicforcesoncivilengineeringstructuresbyvariousactivitiessuchaswalking,jumping,dancing,orhandclapping.Researchintoquantifyingsuchhuman-inducedforceshasbeenongoingformanydecades(Tilden,1913;ASA,1932;GalbraithandBarton,1970;Nilsson,1976;Matsumotoetal.,1978;Wyatt,1985).
Sinceabout1980,experimentallyestablishedhuman-inducedforcetimehistorieshaveusuallybeenapproximatedbyFourierseries.Thereby,thecommonkeyassumptionisthatthehuman-inducedforcesareperfectlyperiodic.ThefactorscorrespondingtoeachsinusoidalcomponentofthisFourierseriesarenameddynamicloadfactors(DLFs)andarereportedinanumberofpublications(Pernica,1990;Bachmannetal.,1995;Kerr,1998).However,assuminghuman-inducedforcesasperfectlyperiodicisquestionablebecausetheyareinessencenarrow-band(Eriksson,1994).Analternativeapproachistodefinehuman-inducedforcesasauto-spectraldensity(ASD)functions(McConnell,1995)inthefrequencydomain(Ohlsson,1982;TuanandSaul,1985;MouringandEllingwood,1994;Eriksson,1994).
Dynamicforcesinducedbycrowdsareanissueofgreatconcern(Kasperski,2001),ascanbeseeninanincreasingnumberofpublicationsdealingwithcrowd-inducedvibrations.Nevertheless,thequantificationofcrowd-inducedforcesstillneedsadditionalresearch.Inparticular,thedependencyofthenatureandmagnitudeofinducedforcesonthesizeoftheactivecrowdandperceptiblemotionofthestructureiscurrentlynotclear(IStructE,2001).
Althoughithasbeenfoundthatdynamicloadsinducedbygroupsofpeoplearehigherthanthoseinducedbyindividuals,thehuman-inducedforcesdonotincreaselinearlywiththenumberofpeople.Thisissoevenifpeoplearesynchronisedbyaprompt(EbrahimpourandSack,1992;KasperskiandNiemann,1993)thatcanbeprovidedbymusic,movementsofotherpeople,orperceptiblemovementsoftheoccupiedstructure(Fujinoetal.,1993;vanStaalduinenandCourage,1994).
Interestingly,visualandaudiocontactbetweenpeopleinfluencesand,inprinciple,improvesthesynchronisationofindividuals(Hamam,1994;EbrahimpourandFitts,1996).
Generally,thesynchronisationofpeopleoncivilengineeringstructurescanbedeliberateorunintentional.Deliberatesynchronisation,asinaerobicclassesorcasesofvandalloading,andthusamplificationofvibrationshasbeenanimportantissueforalongtime.Thefollowingquotefromtheoldestreferenceinthisreview(Stevenson,1821:
243-4)clearlydemonstratesthis:
ItisobservedbyMrJohnSmith,oneofthegentlemenabovealludedto,thatwhentheoriginalbridgeofDryburghwasfinished,uponthediagonalprinciplelikeFig.2,ithadagentlevibratorymotion,whichwassensiblyfeltinpassingalongit;themostmaterialdefectinitsconstructionarisingfromtheloosestateoftheradiatingordiagonalchains,which,inproportiontotheirlengths,formedsegmentsofcatenariancurvesofdifferentradii.Themotionofthesechainswerefoundsosubjecttoacceleration,thatthreeorfourpersons,whowereveryimproperlyamusingthemselves,bytryingtheextentofthismotion,producedsuchanagitationinallitsparts,thatoneofthelongestoftheradiatingchainsbrokenearthepointofitssuspension.
Afteralmost200years,Quast(1993)andKasperski(1996)arestillraisingthesameissue.However,theunintentionalsynchronisationofhumanoccupantsisnowalsoconsideredtobeimportant.Itcanleadtostructuralvibrationsstrongenoughtodisturbpeopleintheirmovement(Dallardetal.,2000)and,therefore,structurescanbecomeunserviceableorevenunsafeduetopanic.
Theunintentionalsynchronisationofpedestrianstostructuralmovementsisacaseofhuman-structureinteraction.IthasbeenobservedonseveralfootbridgesasreportedbyPetersen(1972),Bachmann(1992),Fujinoetal.(1993),Dallardetal.(2000),Curtis(2001),NewCivilEngineer(2001)andSample(2001).Acknowledgingthepotentialproblemcausedbythisphenomenon,designproposalsbySchulze(1980),Vogel(1983),Slavik(1985),GrundmannandSchneider(1990)andGrundmannetal.(1993)includevariousmeansofdealingwithit.
ResearchintothereasonsforandtheextentofsynchronisationbetweenpedestriansandfootbridgeshasbeenperformedbySchneider(1991)andFujinoetal.(1993).Recently,newresearchintothisknown,butlittleunderstoodphenomenon,waspromptedbystrongpedestrian-structuresynchronisationduringtheopeningoftheMillenniumBridgeinLondoninJune2000(Parker,2000;Fitzpatrick,2001).
Itshouldberealisedthathuman-structuresynchronisationisonlyoneaspectofhuman-structureinteractioninfluencinghuman-inducedforces.Infact,human-inducedforcesmaydependonthestiffnessofthesurfaceonwhichpeopleperform(Pimentel,1997).Indeed,BaumannandBachmann(1988)reportedDLFsofwalkingtobeupto10%higherifmeasuredonstiffgroundandnotonaflexible19mlongprestressedbeam.Similarly,biomechanicalresearchonjumpingidentifiedhigherhuman-inducedforcesonstifferstructures(Farleyetal.,1998).Inthiscontext,itisimportanttonotethatavastamountofongoingbiomechanicalresearchintohumanlocomotion(FarleyandGonzalez,1996;FerrisandFarley,1997;Hoffmanetal.,1997;Farleyetal.,1998;Minettietal.,1998;FarleyandMorgenroth,1999)canprobablyaddvaluableknowledgetohuman-inducedforcesoncivilengineeringstructuresbutthereislittleevidenceofcross-fertilisation.
Actually,civilengineersfirstinvestigatedtheinteractionofhumanimpactorsandflexiblestructuresmorethan20yearsago.Inthisresearch,individualsshoulderingpartitionwalls(Struck,1976)ordroppingontoplanksandboards(Mann,1979;StruckandLimberger,1981)wererepresentedbysimplemass-springmodelsandtheflexiblestructuresweremodelledasmass-springsystemsalso.Morerecently,FoschiandGupta(1987),FolzandFoschi(1991),Foschietal.(1995)andCanisius(2000)lookedatimpactor-structureintera
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