Comparative Performance Of Prestressed Concrete Beams by FRP Wrapping

Abstract

Comparative behavior of prestressed concrete (PSC) beams subjected to two point loadings in terms of failure load deflection & failure modes is evaluated. Effect of Glass fiber reinforced polymer (GFRP) strengthening on PSC beams before & after first cracking is measured. Experiment includes testing of nine simply supported PSC beams having cross-section I5O mm x 200 mm with effective span of 3.0 meter. Three unwrapped PSC beams, three PSC beams wrapped by GFRP after initial loading upto first crack & and three uncracked PSC beams strengthened using GFRP are tested upto failure. Three different wrapping patterns are executed on beams. For (2L/7) .span loadings, wrapping or full length at bottom and upto 1/3rd of depth is provided, Forming a U-shape around the beam cross-section. For (2L/4) span loading, wrapping of full length at bottom and upto l/3rd of vertical depth is provided and extra wrapping near the supports is provided. For (2L/3) span loading, U shape wrapping is provided near the supports, for full depth. It is observed that in (21/7) span loadings, compared to unwrapped PSC beams, the FRP wrapping along longitudinal direction, reduces deflections and increases the load carrying capacity for wrapped PSC beams. In (2L/4) span loading, combination of vertical and horizontal GFRP sheets, together with a proper epoxy adhesion, lead to increase the ultimate load carrying capacity for wrapped PSC beams. In (2L/3) span loading, presence of vertical GFRP sheets near support reduces the shear effects considerably and increase load carrying capacity.