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1THEMAINPROBLEMSOFDOMESTICBRIDGEDESIGNINGNow,thecountry'sstructuraldesignprocess,suchtendencies:moreintensityconsideredinthedesignanddurabilityconsiderlessattentionintensitylimittotheuseofstatewithoutlimitstate,andthroughoutthelifecycleofthemostimportantwhenitispreciselytheuseofperformance;attentiontotheconstructionofthestructurewithoutattentiontothemaintenanceofthestructure.Infact,thecurrentdesignofthebridgeformoredurabilityisaconcern,asaconcept,didnotexplicitlyputforwardtherequestoftheuseoflife,northedurabilityofspecializeddesign.Thesetendenciestoacertainextent,ledtothecurrentprojectaccidents,theuseofpoorperformance,theshortlifeoftheadverseconsequencesofstructuralengineeringwiththeincreasingemphasisoninternationaldurability,safety,contrarytothetrendofapplicability;doesnotconformtothestructuredynamicandcomprehensiveeconomyrequirements.Bridgesafety,durability,themainreasonforpoor1)ConstructionandmanagementoflowlevelMorebridgesathomeandabroaddestructionandthesuddencollapseofthebridgehasbeenengineeringmoreconcernedaboutsecurityissues.Thegeneralviewisthatthecurrentprojectisbarbaricincidentmanagementandconstructioncausedbycorruption.Fortheshortterm,suchasthedestructionandcollapseofasudden,mostlybecauseofconstructionqualitydidnotmeetspecificationsanddesignrequirements,typicalproblemsincludeinadequateandconstructionmaterialsintensityoffailure;alsoexist,suchasindividualbridgejerryseriousmanagementissues,butalsoonbridgesafetyofthefataldamage.Andalargenumberofbridgesinthefardidnotachievetheexpectedlifetime,therehasbeenaffectingthenormaluseofdiseaseanddeterioration,especiallyinanumberofbridgesinuseonlyafewyears,orevenjustcompletedsoonontheseriousproblemofinsufficientdurability,whichandthelowqualityofconstructionisanimportantrelationship,thetypicalproblemsofinadequateprotectionofreinforcedandthecurrentwidespreadintheconstructionsiteoftheseriousproblemofcrackingcomponent.Theseconstruction,althoughshort-termdeficienciesofthebridgewillnotbethenormaluseofaclearimpact,butthelong-termdurabilityofthestructurewillhaveaverynegativehazards.2)DesigntheoryandstructureofthesystemisnotperfectenoughWhileacknowledgingtheexistenceoftheproblem,butitalso,itisundeniablethatbridgedesignfields,inparticularonthebridgeconstructionanduseoftheissueofsafetythereisstillmuchimprovement.Structuraldesignfirstandforemosttaskisthechoiceofreasonableeconomicprogrammer,followedbythestructuralanalysisanddesignofcomponentsandconnections,andaccesstoregulatethesafetyfactorspecifiedorreliabilityofindicatorstoensurethesafetyofthestructure.Manydesignersoftencomplacentwithnormsonthestructuralstrengthofthesafetyoftheneed,andignorethestructuralsystem,structure,structure,structureofmaterials,structuremaintenance,aswellasfromthestructuraldurabilityofthedesignandconstructionprocesstomakeuseofthatoftenappearinthe2man-madewrongareastostrengthenandguaranteethesafetyofthestructure.Somestructuralintegrityandductilityinadequateredundancysmall,butsomeofSchemaandtheuncertaintyoftheline,causingpartialexcessiveforce;someconcretestrengthgradetoolowtoprotectslicethroughsmalldiametersteelmicromanage,athincross-sectioncomponentsofthesestructureshaveweakenedthedurability,itwouldseriouslyaffectthesafetyofthestructure.Manybridges,althoughthedesignspecificationsmeettherequirementsofthestrengthofonly5to10yearsbecauseofthedurabilityoftheproblemsaffectingstructuralsafety.StructuralDurabilityshortagehasbecomeoneofthemostrealisticsecurityissues,fromdesigntoconstructionandmaterials,suchasangleofmeasurestostrengthenthedurabilityofthestructure.Oftheenvironmentandtheuseofdifferentconditions,differentdesignofthestructuralsystemwilltargetdifferentaspectsofthelayoutandstructurerequirements.Normscannotcoverindetailthedesignstaffshouldsolvethevariousproblemsintheupdatednormsfastercanalsoadapttonewunderstanding,newtechnologies,newmaterials,rapiddevelopmentofthestructureofthenewrequirements.Therefore,reasonableandreliableadditiontothestructuresisdesignedtomeettherequirementsofnorms,andtodesignastructuretothecorrectunderstandingofnature,richexperienceandaccuratejudgments.Andtheneedtoimproveeffortsinthedirection1)ShouldpaymoreattentiontothedurabilityofstructuralproblemsBridgeintheconstructionanduseoftheprocess,willbesubjecttoenvironmental,andtheerosionofharmfulchemicalsubstances,andtobearvehicles,wind,earthquake,fatigue,overloading,humanfactors,suchasexternalrole,andbridgematerialsusedbytheself-degradationofperformancewillcontinue,resultinginthestructureofthedifferentdegreesofdamageanddeterioration.Inthefieldoflong-spanbridges,andfromthecountrysincethe1980s,theconstructionofalargenumberofcable-stayedbridge,althoughsofartherecollapseorseriousdamagetothefewexamples,buthasmorebridgesbecauseofthedurabilityofcabletotheproblemadvanceforcable,andthisnotonlyaffectstheuseofincreasedeconomiclosses.Needstobepointedoutisthatmanyoftheseproblemsanddidnotconductareasonabledurabilityofthedesign,whichhasalsopromptedrenewedawarenessofdurabilityofthebridge.Diseasesarealotofexamplesofthat,inadditiontoconstructionmaterial