土木工程毕业设计外文翻译拱桥的设计和桥梁裂缝产生的原因分析.docx

土木工程毕业设计外文翻译拱桥的设计和桥梁裂缝产生的原因分析.docx

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土木工程毕业设计外文翻译拱桥的设计和桥梁裂缝产生的原因分析

本科毕业设计

中英文翻译

专业名称：

土木工程

年级班级：

XXX

学生姓名：

XXX

指导教师：

XXX

土木工程学院

二○一二年六月一日

Designofarchbridgesandthebridgecrack

producedthereasontosimplyanalyse

Thischapterconsidersthefullrangeofarchbridgetypesandarangeofmaterialspresentingseveralcasestudiesanddescribingthedesigndecisionsthatweremade.Ageneraltreatmentoftheanalysisofarchesispresented,includingthederivationofthebasicequationsthatcanbeusedtoundertakehandcalculationswhichmaybeusedtovalidatecomputeranalysisoutput.Detailedarchbridgedesignisoutsidethescopeofthischaptersoonlygeneralissuesarediscussed.Mostofthechapterisdevotedtomasonryarchbridges.Masonryarchbridgeconstructionisdiscussedinitshistoricalcontextandtheimportanceforengineerstotakeaholisticapproachtobridgeassessmentanddesignisemphasized.Thereisasignificantsectiononbridgeassessmentwhichincludesguidanceintheapplicationofcurrentandemergingassessmentmethods.Thisisunderpinnedwithbackgroundinformationregardingthematerialpropertiesofmasonry.Thechapterconcludeswithatreatmentofrepairandmaintenancestrategiesincludingacomprehensivetablewhichconsiderscommonremedialandstrengtheningmeasures.

Theoriginsoftheuseofarchesasastructuralforminbuildingscanbetracedbacktoantiquity（VanBeek,1987）.IntryingtoarriveatasuitabledefinitionforanarchwemaylooknofurtherthanHooke’sanagramof1675whichstated‘Utpendetcontinuumflexile,sicstabatcontinuumrigiduminversum’–‘ashangstheflexibleline,sobutinvertedwillstandtherigidarch’.Thissuggeststhatanygivenloadingtoaflexiblecableiffrozenandinvertedwillprovideapurelycompressivestructureinequilibriumwiththeappliedload.Clearly,anyslightvariationintheloadingwillresultinamomentbeinginducedinthearch.Itisarrivingatappropriateproportionsofarchthicknesstoaccommodatetherangeofeccentricitiesofthethrustlinethatisthechallengetothebridgeengineer.EvenintheMiddleAgesitwasappreciatedthatmasonryarchesbehavedessentiallyasgravitystructures,forwhichgeometryandproportiondictatedaestheticappealandstability.Compressivestrengthcouldberelieduponwhilsttensilestrengthcouldnot.Baseduponexperience,manyempiricalrelationshipsbetweenthespanandarchthicknessweredevelopedandappliedsuccessfullytoproducemanyelegantstructuresthroughoutEurope.

Theexpansionoftherailwayandcanalsystemsledtoanexplosionofbridgebuilding.Brickworkarchesbecameincreasinglypopular.WiththeconstructionoftheCoalbrookdaleBridge（1780）aneweraofarchbridgeconstructionbegan.Bytheendofthenineteenthcenturycastiron,wroughtironandfinallysteelbecameincreasinglypopular;onlytobechallengedbyferrocement（reinforcedconcrete）attheturnofthecentury.

Duringthenineteenthcenturyanalyticaltechniquedevelopedapace.Inparticular,Castigliano（1879）developedstrainenergytheoremswhichcouldbeappliedtoarchesprovidedtheyremainedelastic.Thisconditioncouldbesatisfiedprovidedthelineofthrustlaywithinthemiddlethird,thusensuringthatnotensilestresseswereinduced.Therequirementtoavoidtensilestressesonlyappliedtomasonryandcastiron;itdidnotapplytosteelorreinforcedconcrete（ortimberforthatmatter）asthesematerialswerecapableofresistingtensilestresses.

Twentiethcenturyarchbridgeshavebecomeincreasinglysophisticatedstructurescombiningmodernmaterialstocreateexcitingfunctionalurbansculptures.

Typesofarchbridge

TherelevanttermsthatareusedtodescribethevariouspartsofanarchbridgeareshowninFigure1.Archesmaybegroupedaccordingtothefollowingparameters:

1.thematerialsofconstruction

2.thestructuralarticulation

3.theshapeofthearch

Historically,archbridgesareassociatedwithstonemasonry.Thisgavewaytobrickworkinthenineteenthcentury.Becausethesewereproportionedtominimisethepossibilityoftensilestress,theytendtobefairlymassivestructures.Bycomparisontheuseofreinforcedconcreteandmodernstructuralsteelgivestheopportunityforslender,elegantarches.

Nowadays,timberisrestrictedtosmallbridgesoccasionallyinatrussformbutmoreusuallyaslaminatedcurvedarches.Althoughtimberhasahighstrengthtodensityratioparalleltothegrain,itisanisotropicandstrengthpropertiesperpendiculartothegrainarerelativelyweak.Thisrequirescarefuldetailingofconnectionstoensureeconomicuseofthematerial.

Withregardtostructuralarticulationthearchcanbefixedorhinged.Inthelattercaseeitherone,twoorthreehingescanbeincorporatedintothearchrib.Whilstthefixedarchhasthreeredundancies,theintroductionofeachhinger