资源描述：
《建筑 土木工程 外文翻译 外文文献 英文文献 混凝土桥梁》由会员上传分享，免费在线阅读，更多相关内容在工程资料-天天文库。
1、ConcreteBridgesConcreteisthemost-usedconstructionmaterialforbridgesintheUnitedStates,andindeedintheworld.Theapplicationofprestressingtobridgeshasgrownrapidlyandsteadily,beginningin1949withhigh-strengthsteelwiresintheWalnutLaneBridgeinPhiladelphia,Pennsylvania.AccordingtotheFederalHi
2、ghwayAdministration’s1994NationalBridgeInventorydata,from1950totheearly1990s,prestressedconcretebridgeshavegonefrombeingvirtuallynonexistenttorepresentingover50percentofallbridgesbuiltintheUnitedStates.Prestressinghasalsoplayedanimportantroleinextendingthespancapabilityofconcretebri
3、dges.Bythelate1990s,spliced-girderspansreachedarecord100m(330ft).ConstructionofsegmentalconcretebridgesbeganintheUnitedStatesin1974.Curretly,closeto200segmentalconcretebridgeshavebeenbuiltorareunderconstruction,withspansupto240m(800ft).Lateinthe1970s,cable-stayedconstructionraisedth
4、ebarforconcretebridges.By1982,theSunshineSkywayBridgeinTampa,Florida,hadsetanewrecordforconcretebridges,withamainspanof365m(1,200ft).Thenextyear,theDamesPointBridgeinJacksonville,Florida,extendedtherecordto400m(1,300ft).HIGH-PERFORMANCECONCRETECompressiveStrengthFormanyyearsthedesig
5、nofprecastprestressedconcretegirderswasbasedonconcretecompressivestrengthsof34to41MPa(5,000to6,000psi).ThisstrengthlevelservedtheindustrywellandprovidedthebasisforestablishingtheprestressedconcretebridgeindustryintheUnitedStates.Inthe1990stheindustrybegantoutilizehigherconcretecompr
6、essivestrengthsindesign,andatthestartofthenewmillenniumtheindustryispoisedtoaccepttheuseofconcretecompressivestrengthsupto70MPa(10,000psi).Forthefuture,theindustryneedstoseekwaystoeffectivelyutilizeevenhigherconcretecompressivestrengths.Theready-mixedconcreteindustryhasbeenproducing
7、concreteswithcompressivestrengthsinexcessof70MPaforover20years.Severaldemonstrationprojectshaveillustratedthatstrengthsabove70MPacanbeachievedforprestressedconcretegirders.Barriersneedtoberemovedtoallowthegreateruseofthesematerials.Atthesametime,owners,designers,contractors,andfabri
8、catorsneedtobemorer
