Chapter J Bridges

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1、JBridgesJ.1ConcreteBridgesSubjecttoBlastLoadsJ.1.1IntroductionAstandardprecastconcretebridgeconsistsof12standardI-beamsplacedat1.5mc/csupportingreinforcedconcretedeckslabasgiveninPlateJ.1.Thedeckcarriesthreelanesandthebeamsareactingincompositewitha150mmthickstructuralslab.T

2、hebridgedeckissupportedbythreeconcretepiersplacedat5.2mdistancefromeachother.Itisdecidedtodesignthisbridgefirstandthenitissubjectedtoblastloadsatsuitablepositions.Blast-resistantdesignhastraditionallybeenconsideredonlyforessentialgovernmentbuildings,militarystructures,andpet

3、rochemicalfacilities.RecentterroristthreatstobridgesinCaliforniaandNewYorkhavedemonstratedtheneedtoevaluatethevulnerabilityofourtransportationinfrastructure.Bridgeengineers,however,havenottypicallyconsideredsecurityinthedesignprocessandmostofthecurrentstateofknowledgeofthed

4、esignofstructuressubjectedtoblasteffectsisbasedontheperformanceofbuildingsratherthanbridges.Beforeengineerscanbegintodesignbridgestowithstandblastloads,theyneedtodevelopanunderstandingoftheprinciplesofblastwavepropagationanditspotentialeffectsonbridgestructures.Throughtheuseo

5、fcomputer-basedsimulation,wecangainabetterunderstandingofblasteffectsonbridgecomponentsandprioritiseoureffortsforexperimentalstudiesofthemostpromisingretrofitsolutions.Todesignbridgestowithstandterroristattacks,changesneedtobeincor-poratedintothedesignproves.Thetestgivesausefu

6、lapproachforsecurityandredundancyandcanbefollowedforbridges.Duringtheinitialstagessecu-ritycanbeincorporatedthroughsitelayoutprinciplessuchastheeliminationofdarkhidingspacesbyincludingadditionallighting,plantingprotectivelandscapingtoincreasethestandoffdistancetopiers(ensuri

7、ngthatover-grownvegetationwillnotinterferewithlinesofsighttocriticalareas),and1130JBridgesA400100007no:drawnstrand/15.2Total13no:100spacingsDeckcrosssection1010AFootpath3650LaneoneALanetwo25/15.23650stdstrand3650FootpathASteelplatesPlainrubberplatelaminatedrubberfixedtypeLi

8、nkwallVar.footingT32-125T20or20U-100ReinforcedconcretefoundationT12-250T20-200Symm