Behavior of Presressed Concrete Beams Using GFRP Wrapping

Abstract

Comparative behavior of Prestressed concrete (PSC) beams subjected to two point loadings in terms of failure load, deflection and failure modes is evaluated. Effect of Glass Fiber Reinforced Polymer (GFRP) strengthening on PSC beams before and after first cracking is measured. Experiment includes testing of twelve simply supported PSC beams having cross-section 150 mm x 200 mm with effective span of 3.0 meter. Four unwrapped PSC beams, four PSC beams wrapped by GFRP after initial loading upto first crack and four uncracked PSC beams strengthened using GFRP are tested upto failure. Four different wrapping patterns are executed on beams. For (2L/7) & (2L/ 6) span loadings, wrapping of 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 1/3rd 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 (2L/7) & (2L/6) 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.