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Alternativesforbridgesurfacingswithorthotropicplateddeck:afatiguepointofview
7
ofthisistheCalandbridgeinRotterdam,whichwasexaminedmorecloselyand
whereseveredamageduetocrackingandfatiguehasbeenfound.InBelgium,
largespanbridgeswithorthotropicplateddeck(forinstancetheVilvoorde
viaduct)donotsufferfromthiscracking,butsmallermovablebridgesalsoshow
thissensitivity.Thissituationhastobeconsideredinviewoftheeverincreasing
axleloadsandmorecompactwheelloadsintroducedbyroadtraffic.Thedesign
andfatigueloadsasmentionedbyprEN1997-2[2],thatwereintendedashigher
bondvaluesofEuropeantrafficmaywellbecirculatingfrequentlyatpresent.In
viewoftheseconsiderations,theconclusionmustbetofindsystemstodecrease
theaggressiveeffectsofconcentratedwheelloadsonorthotropicplateddecksor
toeliminatetheseeffects.
Fig.1.Finiteelementmodel,showingthedifferentgroupsoffatiguesensitivelocations
1.4.Objectiveoftheresearchprogram
Whentryingtoimprovethefatiguebehaviorofacertainbridgetype,one
hasonlytwopossibilities.Thefirstoneistoreducethenumberofstresscycles,
thesecondoneistoreducethestressrangesinallfatiguesensitivedetails.
Sinceitisnottheobjectiveofthisstudytomakeradicalchangestothe
orthotropicdeckconcept,thispapertriestofindsolutionsby
installinganextra
layerontopofthesteeldeckplate,thusimprovingtheloaddispersal
beforeitreachesthedecksurface.Severalpossibilities,suchasasphaltlayers,
independentrubber,syntheticorevenFRPmatsaswellasaluminumorFRP
sandwichpanelsareconsideredandwerestudiedinitiallyusingfiniteelement
modeling[3],[4]andlaboratorytesting[5],[6]toprepareforthefullscalefield
testing.
