Strengthening Of Preloaded RC Beam Containing Square Opening Located At Shear Zone by GFRP and CFRP Sheets

This experiment work is carried out study of “strengthening of preloaded RC beam containing small square opening located at shear zone by Glass Fiber Reinforced Polymer (GFRP) and carbon Fiber Reinforced Polymer (CFRP) sheets� in order to investigate the efficiency of external strengthening with GFRP and CFRP sheets. In this experimental work total eight beams were cast. All beams have dimensions of 150mm width, 250mm depth and 2000mm length. The first beam is solid beam and second beam is cast with opening but not strengthened referred as control beam. The loading has been carried out in two stages. In the first stage the solid beam and control beam are tested up to the ultimate load. The ultimate load of control beam is 80kN. The next three beams B1, B2, B3 are preloaded up to 30%, 45%, and 60% of ultimate load (i.e. 80kN) respectively. The last three beams B4, B5, B6 are also preloaded up to 30%, 45%, and 60% of 80 KN respectively. In the second stage the preloaded beams B1, B2, and B3 are strengthened with GFRP sheets and the preloaded beams B4, B5, and B6 are strengthened with CFRP sheets. All beams were tested in loading frame with two point loading up to failure. The test results revealed that the beams B1 to B6 strengthened with CFRP and GFRP sheets have shown percentage increase in load carrying capacity as compared to control beam. The control beam has shown a decrease in the load carrying capacity by 24% as compared to the solid beam. The increase in load carrying capacity of preloaded beams B1, B2, and B3 strengthened with GFRP sheets is 22.5%, 17.5% and 15% respectively as compared to the control beam, whereas in case of preloaded beams B4, B5, and B6 strengthened with CFRP sheets the increase in load carrying capacity observed is 32.5%, 27.5% and 22.5% respectively as compared to the control beam. The beams B1 and B4 strengthened with GFRP and CFRP sheets respectively and both preloaded to 30% have shown a higher load carrying capacity as compared to beams with higher preloading’s. In all the six beams, the percentage increase in load carrying capacity is more in case of beams strengthened with CFRP as compared to beams strengthened with GFRP. From the overall study it can be concluded that the application of CFRP and GFRP sheets reduces the excessive cracking and beam deflection and increases the ultimate load carrying capacity and stiffness of the beam. The use of CFRP and GFRP sheets wrapping with the designed strengthening configuration could significantly reduce excessive cracking, deflection and increases the ultimate capacity, stiffness of beam.