Abstract—In modern buildings construction opening in beams are more often used to provide passage for utility duct and pipes. As a result storey height and material cost can be reduced. However providing an opening in the beam causes cracks around opening reduces load carrying capacity of the beam. In this experiment total eight beams were casted. The first beam is solid beam and second beam is casted 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 was 80 KN. The next three beams B1, B2, B3 are subjected to preloading up to 30%, 45%, 60%, respectively of 80 KN. The last three beams B4, B5, B6 are also subjected to preloading up to 30%, 45%, 60% respectively of 80 KN. In the second stage the preloaded beams B1, B2, B3 are strengthened with GFRP sheets and the preloaded beams B4, B5, B6 are strengthened with CFRP sheets. The test results revealed that the load carrying capacity of the control beam has shown a decrease in strength by 24.5% as compared to the solid beam. The increase in load carrying capacity of the beams strengthened with GFRP and CFRP observed was 17.5% and 32.5%, respectively as compared to the control beam. The beams B1 and B4 strengthened with GFRP and CFRP respectively and both preloaded to 30% have given a higher strength as compared to beams with higher preloading¡¯s. In all the six beams, the percentage increase in strength is more in case of beams strengthened with CFRP as compared to beams strengthened with GFRP.

Index Terms—Reinforced concrete beams, Circular opening, Glass Fiber Reinforced Polymer (GFRP) sheets, Carbon Fiber Reinforced Polymer (CFRP) sheets, Preloading, strengthening

Cite: Sagar and Shivaraj Mangalgi, "Strengthening of Preloaded RC Beams Containing Circular Opening at Shear by Using CFRP and GFRP Sheets," International Journal of Structural and Civil Engineering Research, Vol. 4, No. 1, pp.37-49, February 2015.