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1摘要本设计所设计的是预应力混凝土连续梁桥的设计，该桥位于宁夏王洼到原州区段，为单线铁路桥梁，主要设计桥梁的上部结构，设计荷载采用中—活载。本设计采用预应力混凝土连续梁桥，其孔径布置为48+80×2+48m，全长为256m，主梁采用变高度变截面的单箱单室箱型截面，施工方法采用对称悬臂施工法。本设计使用midas软件分析，考虑施工过程体系转换和混凝土收缩徐变因素进行恒载内力计算。计算各控制截面内力影响线，并按最不利情况进行加载，求得活载内力包络图。定义基础沉降组，按最不利组合求得基础沉降引起的最不利内力。依据规范选取截面梯度温差模式，并计算温差引起的结构内力。分别按主力组合和主力附加力进行荷载组合，并得到结构组合内力包络图。根据各控制截面内力进行了估束和配筋计算，并绘制了梁体钢束布置图。最后，对各控制截面进行了强度、抗裂性、应力和变形验算，各项检算均满足规范对全预应力结构的要求。关键词：连续梁；内力计算；预应力混凝土；检算；2AbstractWhatIdesignedattheundergraduatedesignisaprestressedconcretecontinuousbeambridge.ItliesinWangwatoYuanzhou，Ningxiaprovince.Itisasinglelinerailway.Imainlydesignedthesuperstructureofthebridge.Theloadfordesignisthe“zhonghuo”load.Iadoptaprestressedconcretecontinuousbeambridgewithfourspansof48+80×2+48m，Itstotalspanis256m.Firstthesizeofgirderisdetermined；highlyvariableforthevariablebeamcross-sectionsingle-BoxSinglegirderandbalancedcantileverconstructionisused.ThentheMidasprogramisusedtocalculatetheinternalforcecausedbydeadloadofthefirststage，consideringtheconstructionstage，afterimposingthesecondstagedeadloadonthecompletesystem.Theinternalforceofthestageiscalculated.Theinternalforceinfluencelinesofthecontrolsectioniscalculated，thentheliveloadisimposedaccordingtothemostadversecircumstancestogettheForceEnvelope.Theprogramisusedtodeterminethemostadversecircumstancesandcalculatetheinternalforceafterdefiningthesettlementgroupsofthebasis.Thetemperatureloadisimposedconsidertheshrinkageandcreepoftheconcrete.ThencombinationofloadeffectsismadeacoordingtotheMainforcecombinationandtheMainforceplusadditionalforcecombination.Accordingtotheinternalforceofcontrolsections，thenumberofper-stressingsteelstandsisestimatedandtheper-stressingsteelstandsarearrangedinthebridge.Finallyacheckismadeofthebearingcapacity，theabilitytoresistcrackandthesterssofthecontrolsection，alltherequirementscanbemet.Keywords:Continuousbeam；Internalforcecalculation；Prestressedconcrete；Checkingcomputation；3目录第一章绪论........................................................................................................................1第二章结构尺寸拟定............................................................................................................2第一节总体布置............................................................................................................2第二节细部尺寸拟定......................................................................................................2一、主梁梁高............................................................................................................2二、截面尺寸............................................................................................................2三、各截面细部尺寸................................................................................................3第三节本桥主要材料....................................................................................................3一、混凝土：............................................................................................................3二、预应力钢绞线：................................................................................................4三、箍筋：................................................................................................................4四、应力管道：........................................................................................................4第四节施工方法..............................................................................................................4一、桥墩与零号块施工............................................................................................4二、悬臂施工到最大悬臂状态................................................................................4三、边跨膺架现浇....................................................................................................4四、边跨合拢............................................................................................................5五、中跨跨中合拢....................................................................................................5六、桥面铺装............................................................................................................5第三章预应力混凝土连续梁桥内力计算............................................................................5第一节计算模型建立....................................................................................................5第二节毛截面几何特性计算........................................................................................6第三节恒载内力计算....................................................................................................7一、计算方法............................................................................................................7二、控制截面选择....................................................................................................8三、恒载取值............................................................................................................8四、各施工阶段的内力计算....................................................................................8五、控制截面恒载内力............................................................................................9第四节活载内力计算.