PAGEPAGE7THEMAINPROBLEMSOFDOMESTICBRIDGEDESIGNINGNow,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,aswellasfromthestructuraldurabilityofthedesignandconstructionprocesstomakeuseofthatoftenappearintheman-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,inadditiontoconstructionmaterialsandthereasonsforadecisiveimpactonthedurabilityofthestructurefromthestructuralfactors(isdesign)flaws.Fromthecountryinthe1990sstartedtoattachimportancetothedurabilityofthestructureofthestudy,hasalsomadequiteafewsuccesses.Mostofthesestudiesandstatisticsfromtheanalysisofthematerialpointofview,onhowtostructureanddesignfromtheperspectiveofhowandthedesignandconstructionstafftobereadilyacceptedandoperationofthebridgeapproachtoimprovingthedurabilityhasbeenlittleresearch.Moreover,foralongtime,peoplehavealwaysbeenemphasisonthemethodsofcalculationonthestructure;itignoresthedetailsoftheoverallstructureandprocessingconcern.Designanddurabilityofthestructureofthestructuraldesignofaconventionalnatureofthedifferencebetweenthecurrenteffortswillbeneededonthedurabilityofthequalitativeanalysistothequantitativeanalysisofdevelopment.2)EmphasisonthestudyoffatiguedamageBridgestructuretowithstandthevehicleloadandwindloadaredynamicloadwillbeinacycleofchangewithinthestructureofthestress,notonlywillcausethevibrationofthestructure,butalsofromthestructureoftheaccumulatedfatiguedamage.Thebridgeisnotusedbythematerialisuniformandcontinuous,infacttherearemanytinyflawsintheroleofcyclicloading,thesedeficiencieswillbeprogressivedevelopmentofmicro,amergerofinjury,andgraduallyformedinthematerialmacrocracks.Ifthecrackisnoteffectivemacro-control,isverylikelytocausematerial,thestructureofbrittlefracture.Earlyfatiguedamageisnotalwayseasytobedetected,buttheconsequencesareoftendisastrous.Fatiguedamagehasbeenconsideredinthedesignofsteelbridgeisthecoreissueoffatiguecausedbythesteelstructureofsteelcrackmorecases,manycausedbyfatiguefracturebridgecollapseexample.Overthepast20years,fatigueinjuryresearchhasenteredtheconcretestructure,butbytheuseofcorrosionofreinforcedconcretestructuresdynamicperformanceandfatiguepropertiesofneedtobestrengthened.Onthefatiguedamageofnotonlyreferstotheentirestructure,thebridgestructureoftenasamatteroffactsomeofthekeypartsoflocalfatiguefailureoftheentirestructureandleadtofailure,suchasthecable-stayedbridgecablesanchoringendofthefatiguedamage.3)PayfullattentiontotheproblemofoverloadingthebridgeTherearethreemainvehicleoverloading:Oneistheearlyconstructionoftheoldbridgeoverageloadcarriersandtheotheristhepassageofvehiculartrafficbridgeovertheoriginaldesign;theotherisillegaloverloadingofvehicles.Thefirsttwoarethemainreasonsforthechangesinthedesignloadandtheincreaseinthevolumeoftraffic;usersofthelatterareillegaloverloadingofvehiclesoperating,thelattertwophenomenaofoverloadinginroadtransportinChinaismorecommon.Ontheonehand,overloadingthebridgemaytriggerfatigue.Overloadingbridgewouldincreasetherateoffatiguestressinjuryaggravated,orevensomestructuraldamagecausedbyoverloadingaccidents.Ontheotherhand,duetooverloadingofthebridgecausedinternaldamagecannotberestored,thebridgewillbemadeoftheworkundernormalloadconditionschange,whichcouldendangerthesafetyofbridgesanddurability.Forexample,theconcretebridgehasalwaysbeenregardedasanadequatedurability,buttheoverloadingofthevehicle,crackingmayoccur;cracksevenintheloadwillbeabletodivestclosed,buttheinternalstructureofconcretehasbeendamage,crackingcomponentfromthelowerbend,Stiffnessdeclinewasinthenormaluseofload,shouldnothavebeencrackingorstructuralcrackshavebecomesmallercracksinexcessofthenormstoallowalargercracksordeformation.Thesewillbeusedforstructuralperformanceandlong-termdurabilityhasanegativeimpact,inadditiontotheTrafficControldepartmentsshouldstrengthenmanagement,butalsotheneedforoverloadingtheconsequencesofresearch,analysis.鏟4)的Active頌lylea夠rnfro伐mfore次ignex咱perien尊ceand途resul塘ts謝帽妄Domest散icbri旅dgede管signt決hemai狗nprob舒lemsi京sthe磨useof謊then賢ormal爽struct間ureof屋poor規(guī)perfor炭mance皮(refer輔ringc山ompare雞dwith牲thed旁esign扛expect衛(wèi)ations膨canb鄭eattr輪ibuted庭topo丘orper樹forman搖ceof陵theap編plicat計(jì)ion,i姥ncludi卡ngthe安bridg術(shù)etoo鍵muchv殲ibrati侮on,li茅neari聚rregul顫arity,殖joint創(chuàng)s,dia騎rrhea,胖exces撕sives稅tructu幫ralcr獻(xiàn)acking檔and菊deform墓ation,盜etc.)填,dura溫bility嚼ands幻afety腦ofthe押poor夠(inclu騰dings惜hortl貞ifesp輸an,hi爪ghmai尺ntenan伯cecos初ts,an晝dmore給frequ夏entac蠢cident到s,etc欣.).Wh醒ileth瑞eseis贈(zèng)suesh砍avewi辨ththe惰curre堡ntdom肯estic喚constr筒uction悠quali包tyand敵manag松ement賤level倍lower,挺butt普obef修air,s推incet宋hissi糊tuatio疼ncan吐notbe聲r(shí)esol鋼vedin植thes翁hortt廚erm,t砌henas府engin瀉eersw墨eshou壟ldadd守resst擔(dān)hisis傾suein劍thep欄remise集,are沸fully充taken笨intoa辜ccount義stage含ofco扁nstruc仇tiona蜘ndman板agemen云tand蹈materi泡alste雞chnolo鴿gy,th傷euse兆o(hù)fapp原ropria慰tesec封urity,浮thea花ppropr濁iatew拔ayto殊ensure減that乖thede喬signo往fabr沿idget蝶othe鴉useof傲thep障erform翼ance,之thisi亞samo銹repro商active訪ande算ffecti春vemea攜ns.Es擔(dān)pecial棒lythe燥durab此ility招ofthe侵bridg撈eand脖safety哲ofma醒nypro島blems船witht鬧hestr異ucture褲orth根euse驚ofmat研erial豎select界ionar葛eunre流asonab銷leand贊impro屋perha槳ndling卻ofth猜estru糧ctural似detai譜ls.累InEur揪opean自countr深ies(s跳uchas暖Germa姥ny,De判nmark,撲etc.)姐,atta蛇chedg壞reati爭mporta票nceto翁thes瞎tructu竿reof姜aperf觀ormanc箱e-base允ddesi需gn(PB河D,Per容forman簡ceBas停edDes推ign),擺which今includ次esstr統(tǒng)uctura同ldefo翻rmatio回n,cra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例也證明，除寇了施工和材料大方面的原因，玩影響結(jié)構(gòu)耐久舞性的決定性因悔素是來自構(gòu)造憤上（也即設(shè)計(jì)巾上）的缺陷。昌盲國內(nèi)從上紙世泡紀(jì)奇9橋0戀年代開始重視荷了對(duì)結(jié)構(gòu)耐久溜性的研究，也千取得了不少成稈果。這些研究牲大多是從材料飯和統(tǒng)計(jì)分析的艦角度進(jìn)行的，茄對(duì)如何從結(jié)構(gòu)顛和設(shè)計(jì)的角度們及如何以設(shè)計(jì)嫂和施工人員易豐于接受和操作湖的方式來改善旗橋梁耐久性卻務(wù)很少有人研究膀。而且，長期御以來，人們一王直偏重于結(jié)構(gòu)終計(jì)算方法的研根究，卻忽視了蹤對(duì)總體構(gòu)造和祖細(xì)節(jié)處理方面暫的關(guān)注。結(jié)構(gòu)殊的耐久性設(shè)計(jì)趟與常規(guī)的結(jié)構(gòu)搞設(shè)計(jì)有著本質(zhì)翻的區(qū)別，目前連需要努力將耐尸久性的研究從激定性分析向定息量分析發(fā)展。旨撥職2辱）重視對(duì)疲勞泡損傷的研究趴優(yōu)橋梁結(jié)構(gòu)時(shí)所承受的車輛裹荷載和風(fēng)荷載畝都是動(dòng)荷載，蛇會(huì)在結(jié)構(gòu)內(nèi)產(chǎn)屋生循環(huán)變化的汁應(yīng)力，不但會(huì)跡引起結(jié)構(gòu)的振唉動(dòng)，還會(huì)引起菊結(jié)構(gòu)的累積疲霸勞損傷。致怕由于橋梁窮所采用的材料牙并非是均勻和度連續(xù)的，實(shí)際境上存在許多微拍小的缺陷，在眾循環(huán)荷載作用紗下，這些微缺哪陷會(huì)逐漸發(fā)展煉、合并形成損癢傷，并逐步在馳材料中形成宏濱觀裂紋。如果片宏觀裂紋不得音到有效控制，尋極有可能會(huì)引販起材料、結(jié)構(gòu)艙的脆性斷裂。差早期疲勞損傷端往往不易