8/14/2019 Dynamic load testing of Swiss Bridges.PDF http://slidepdf.com/reader/full/dynamic-load-testing-of-swiss-bridgespdf 1/6 Dynamic Load Testing of SwissBridges Essais ynamiquesespontsSuisses Dynamische ersuche n Schwerzerrticken Olivier L. BIJRDET PhD IBAP SwissFederal nstituteof Technology CH-1015 ausanne SWITZERLAND OlivierBurdet,bom n 1960,holdsa PhDfrom the University of Texas at Austin. He is in chargeof field testing for IBAP andalso nvolved nteaching and esearch ctivities.His research interestsncludebridgeevaluation nd mairfienancenddesignby testing. Sqmmary The paperpresents esultsobtainedusinga simple dynamic esting procedure requentlyused n Switzerland for highwaybridges.Typical resultsare shownand tendencies bservedn the dynamicbehaviorof highway bridgesarepresented. or a deteriorated avement,he dynamic mpactof heavyvehicless shown o be larger at lower truck speeds. Some correlation s shown between he dynamic propertiesof the bridge and its stiffiress,as measuredn a static oad est. R6sum6 L'articleprdsenteesrdsultatsobtenusd I'aided'unemdthoded'essaidynamique implefrdquemment tilisde pour esponts outiers en Suisse. e comportementypiquedesouwages,ainsique es endancesdndrales es ponts routiers sont prdsent6s.Dans le cas d'un revCtementd6t6rior6, il est montrd que le coefficient d'amplificationdynamique stplus grand onque la vitessedepassage esvdhiculesestplus frible. Quelques corrdlations ontpr6sentdesnile lespropri6t6s tatiques t dynamiques esponts. Zusammenfassung Im vorliegenden Bericht werden die Ergebnisse einer einfachen Testprozedur fiir dynamische Belastungsversuche riisentiert die in der Schweiz oft fiir Briicke verwendet wird. Typische Versuchsergebnisseund Tendenzen der Arfobahnbriicken werden pr?isentiert. Bei beschiidigter Fahrbahnfliichest der dynamischeAmplifikationsfaktor bei kleineren Fahrgeschwindigkeiten ft griiBer. GewisseKonelationenzwischendenstatischen nddynamischenBriickeneigenschaftenerdenaufpzeigt. StdphaneCORTHAY Assistant IBAP SwissFederal nstinrteof Technolory CH-1015 ausanne SWITZERLAND Stdphane orthay,bom n 1967,holdsa Civil Engineering egree rom EPFL. He is involved n staticanddynamic load estingof bridges.
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8/14/2019 Dynamic load testing of Swiss Bridges.PDF
pour esponts outiersen Suisse. e comportementypiquedesouwages,ainsique es endances dndrales esponts routiers sont prdsent6s.Dans le cas d'un revCtementd6t6rior6, il est montrd que le coefficient
d'amplificationdynamique stplus grand onque la vitessedepassage esvdhiculesestplus frible. Quelquescorrdlations ontpr6sentdesnile lespropri6t6s tatiques t dynamiques esponts.
Zusammenfassung
Im vorliegenden Bericht werden die Ergebnisse einer einfachen Testprozedur fiir dynamische
Belastungsversuche riisentiert die in der Schweiz oft fiir Briicke verwendet wird. Typische
Versuchsergebnisseund Tendenzen der Arfobahnbriicken werden pr?isentiert. Bei beschiidigter
Fahrbahnfliichest der dynamischeAmplifikationsfaktorbei kleineren Fahrgeschwindigkeiten ft griiBer.
Dynamic oadtesting s an importantpart of the acceptancerocess or new bridges n Switzerland SI. As acomplemento static oadtests,dynamic estsyield useful nformationabout he actualbehaviorof the bridgeunder traffic. This information s usually difficult to obtain analytically,becauseof the complexity of theactualstructure.The effect of pavementdeteriorationon the dynamic esponse f the bridge s of particular
importanceor theflumagement f the structure.This informationcanbeeasily and realisticallyobtained roma dynamic est,and hereafterusedby the highwayautlroritieso organizehepavementnaintenance.
Drawing on the largenrxnberof testsperformedby IBAP overthe past wentyyears, he paperdescribeshegeneraldynamiccharacteristics f highwaybridges.Somecorrelation s shownbetweenhe stiffiressobtainedin a static load test andthe measured igenfrequencies.he influenceof the speedof a vehiclecrossing hebridge s discussed.n particular, he effectof an artificialdamagen thepavement n the dynamicbehavior spresented.
2. Dynamic Load Testing
Thepurposeofthe dynamic oad est s to determinehecontrollingparameters fthe dynamicbehaviorof thebridges. The main dynamic characteristicsof the structwe are the fundamentalvibration frequency, hedynamicamplificationfactor and the logarithmicdecrement.Thesepropertiesarc usually not analyzed ndetail in the desrgnphaseof small and middle sizedstructues. Somepararneters, uchas the logmithmicdecrementor the dynamicamplificationfactor, can only be roughly estimatedat the time of the design.However, hesequantitiesarerelativelyeasy o obtainexperimentally, ndcangive valuable nformation orthe exploitationandmainteruulcefthe bridge.
The generalmethodology sed n the dynamic oadtestof a bridgewill be presented singasanexamplehe
bridge shown in figure 1. The Riddes-Leytronbridge is a cable-stayedstructgrewith a slender declqsupporting wo lanesof traffic and a sidewalk.The bridge was built from 1991 o 1992 arfi tested n thesummer f 1992.
i -j :,==::i:::::.::-:i ::-:i
i ii 11.39m i+ - - - >
b) CrossSection) Side ViewFigure l: Geometryofthe Riddes-Leyhon bridge
3. Methodology
Dynamic oadtesting s performedby exciting hevibrationofthe bridgeandby measwing ts propertiesafterthe excitationhasceased.Severalmettrods re available or theexcitationofthe bridge, n particular:eccentricrotatingnrrsses, mpactof a heavyweightandpassage f a loaded ruck. This lastmethod s oftenpreferredfor the dynamic oad testingof bridgesbecauset gives,alongwith reasonably ccurate aluesof the above
8/14/2019 Dynamic load testing of Swiss Bridges.PDF