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I摘要预应力钢束是对预应力混凝土桥梁构架当中十分重要的部件，其性能的好坏直接决定整体的使用情况，预应力损失很大程度上会对桥梁的形状、结构以及使用年限产生很大的影响。因此，对于钢束有效预应力检测、评估以及相关的计算，对预应力混凝土桥梁具有十分重大的意思价值。本文针对这种情况进行了系统性的探讨。国家为推动西部经济落后地区的交通建设和发展,国家主导开展大中跨径混凝土桥梁应力技术研究项目,并取得了巨大的科研成果,本文正是与其研究成果进行比较,借助相关专家研究出的预应力钢束沿程分布规律的探究成果，进行了详细的探究。在实桥预留测点处，通过横张位移增量法检测方法对钢束的有效预张力进行相应的检测，通过一定的规律计算出实际数据。对桥梁的结构数据建立科学化的模型，同时，遵循一定的规律计算出相应的数据。并且通过钢束有效预应力实际测试结果和计划值做详细的对比，以此来判别当前阶段与影流损失的情况。同时，根据规状态下主梁上下缘混凝土应力实际布局状况，按照相应的标准进实际的操作，同时对已经通过抽检的钢束预应力进行测量出实际值。桥梁在实际使用阶段，会因为各种各样复杂的原因而产生相应的影响，特别是预应力损失造成的影响。因此，为了更好的保障桥梁的安全性问题，本文通过利用MIDAS空间模型，同时，考虑到更多可能的发生的状况，对桥梁的安全性做出了相应的检验分析，从理论情况来看，该座大桥在投入使用30年后很大程度上会出现开裂的现状，因此，强烈建议在地板出预留管道处添加相应的预应力钢束或者是增添体外预应力束以此来增强大桥的强度。关键词:预应力损失，有效预应力预测，结构安全性分析。IIAbstractPrestressedsteelbeamisveryimportantfortheprestressedconcretebridgestructureofthecomponents,itsperformancedecidestheoverallusage,theprestresslosswilllargelyaffecttheshape,structureandservicelifeofthebigbridge.Therefore,itisofgreatvaluetotheprestressedconcretebridgeforthedetection,evaluationandcalculationoftheeffectiveprestressofsteelbeams.Thispapermakesasystematicstudyonthiskindofsituation.Thisarticleonthebasisofwesterntransportprojectsmediumandlargespanprestressedconcretebridgedetectiontechnologyresearchasareference,withthehelpofexpertsoftheprestressedsteelbeamalongthedistributionofresearchresults,carriedoutadetailedinquiry.Theeffectivepretensionofthesteelbeamismeasuredbythemethodofthedisplacementincrementmethod,andtheactualdataiscalculatedbythemethodofthedisplacementincrementmethod.Toestablishascientificmodelofthestructuraldataofthebridge,atthesametime,tofollowcertainrulestocalculatethecorrespondingdata.Bycomparingtheactualtestresultsandtheplannedvalueoftheeffectiveprestressofthesteelbeam,theresultsofthecurrentstageandthelossoftheshadowflowcanbejudged.Atthesametime,accordingtotherulesofthemainbeamonthebottomedgeoftheconcretestressdistributionconditions,accordingtothecorrespondingstandardintotheactualoperation,atthesametimeonthesteelbeamhasbeenmeasuredbythetestoftheactualvalue.Bridgeintheactualuseofthestage,becauseofavarietyofcomplexcausesandthecorrespondingimpact,especiallytheimpactcausedbythelossofprestress.Therefore,inordertobetterprotectthesafetyofthebridge,throughtheuseofMIDASspacemodel,atthesametime,takingintoaccountthemorelikelyoccurrencesituation,thesafetyofthebridgehasmadethecorrespondinganalysistest,fromthetheoreticalperspective,theuseofbridgecrackstatuswillappearafter30yearslargelyininputthereforestronglyrecommendedinthefloorofthepipelineatthereservationandaddthecorrespondingprestressedsteelbeamoraddingexternalprestressedtendonsinordertoenhancethestrengthofthebridge.Keywords:Prestressloss;Effectiveprestressforecast;Analysisofstructuralsafety3目录摘要................................................................................................................................................................1Abstract...........................................................................................................................................................21绪论.............................................................................................................................................................11.1研究背景.........................................................................................................................................11.2预应力混凝土桥梁病害及成因......................................................................................................21.2.1预应力混凝土桥梁病害现象..............................................................................................21.2.2病害成因..............................................................................................................................31.3国内外有效预应力检测研究现状..................................................................................................41.3.1国外研究现状......................................................................................................................51.3.2国内研究现状可加内容....................................................................................................61.4本文研究的目的和主要内容........................................................................................................101.4.1研究目的............................................................................................................................101.4.2主要内容............................................................................................................................111.5研究内容、技术路线和创新点....................................................................................................111.5.1研究内容............................................................................................................................111.5.2技术路线的创新点............................................................................................................121.6本文采用的技术路线....................................................................................................................132有效预应力评价方法.....................................................