quotBEHAVIOUR OF PRESTRESSED CONCRETE BEAMS STRENGTHENED WITH FIBRE REINFORCED POLYMER LAMINATESquot

Abstract

newline quotStrengthening of pre-stressed concrete structures using Fibre Reinforced Polymer (FRP) shows newlinebetter promise for extending their service life. Knowledge about the actual performance of the newlinestrengthened members is an essential prerequisite for an effective application of the technology. newlineThe main objective of this research work is to evaluate the static response of pre-stressed newlineconcrete beams strengthened with externally bonded Fibre Reinforced Polymer (GFRP) newlinelaminates at the soffit of beam. A total of fourteen beams of 3 m length and 150 mm x 250 mm newlinein cross-section were cast and tested in the laboratory. Two unbonded post-tensioned beams newlineserved as reference beams and the remaining twelve beams were strengthened with GFRP newlinelaminates on their soffit. 7 beams cast with M35 grade concrete were strengthened with three newlinedifferent GFRP laminates having two different thicknesses 3 mm and 5 mm and tested under newlinemonotonically increasing loading and manual readings were recorded. Remaining 7 beams newlinecast with M60 grade concrete were strengthened with three different GFRP laminates having newlinetwo different thicknesses 3 mm and 5 mm and tested under monotonically increasing loading newlineand manual readings were also recorded directly. The variables considered included grade of newlineconcrete, type of GFRP laminate and thickness of GFRP laminate. The GFRP laminates also newlinevaried in their configuration, viz., Chopped Strand Mat (CSM), Woven Roving (WR) and Uni- newlineDirectional Cloth (UDC). Responses of all the beams were evaluated in terms of strength, newlinestiffness, ductility, composite action between concrete and external reinforcement and the newlineassociated failure modes for beams tested under static loading. newlineiii newlineThe study parameters considered for this research work included yield load, deflection at yield newlineload, ultimate load, deflection at ultimate load, deflection ductility, deflection ductility ratio, newlineenergy ductility, energy ductility ratio, number of cracks and energy absorption. newlineThe static test results show that the pre-stressed concr