Behavior of bonded and unbonded prestressed normal and high strength concrete beams

Abstract EN

The majordisadvantageofusingordinaryreinforcedconcrete(RC)elementsisthecor- rosion ofsteel,whichoccursduetoeffectofcracksintensionzones.Themainadvantageofthe fully prestressedconcretesystemistheabsenceofcracksintheconcreteatthenominalserviceload and thereforebetterdurabilitywillbeachieved.CombiningthePCsystemwiththeuseofhigh strength concreteisamilestone,whichwillpotentiallyresultinanewdesignapproach.Thedisad- vantage oftheuseofthiscombinationisreferredtothereducedductilityofconcretemembers.

This paperpresentsanexperimentalprogramconductedtostudythebehaviorofbondedand unbounded prestressednormalstrength(NSC)andhighstrengthconcrete(HSC)beams.Thepro- gram consistsofatotalofninebeams;twospecimenswerereinforcedwithnon-prestressedrein- forcement, fourspecimenswerereinforcedwithbondedtendons,andtheremainingthree specimens werereinforcedwithunbondedtendons.Theoveralldimensionsofthebeamsare 160 · 340 · 4400-mm.

Thebeamsweretestedundercyclicloadinguptofailuretoexamineitsflex- ural behavior.Themainvariablesinthisexperimentalprogramarenominalconcretecompressive strength (43,72and97MPa),bondedandunbondedtendonsandprestressingindex(0%,70%and 100%).

Theoreticalanalysisusingrationalapproachwasalsocarriedouttopredicttheflexural behavior ofthespecimens.Evaluationoftheanalyticalworkisintroducedandcomparedtothe results oftheexperimentalwork