BEHAVIOR OF R.C.C. BEAM WITH RECTANGULAR OPENING STRENGTHENED BY CFRP AND GFRP SHEETS

Abstract

In the construction of multistory buildings the opening in beams are provided for utility ducts and pipes. Providing an opening in beam develops cracks around the opening due to stress concentration. In this paper the behavior of R.C.C. beam with rectangular opening strengthened by CFRP and GFRP sheets were studied. This paper presents the behavior of R.C.C. beam with rectangular opening strengthened by CFRP and GFRP sheets with different techniques. In this experimental study total ten beams were casted, one beam without opening (i.e. solid beam) and one beam with rectangular post opening and these two considered as a control beams for comparison. The remaining eight beams were externally strengthened by Carbon fiber reinforced polymer (CFRP) and Glass fiber reinforced polymer (GFRP) sheets with different strengthening techniques i.e. around the opening, inside the opening, inside and around the opening and double layer around the opening. These beams were tested under two point loading in the loading frame. The effect of CFRP and GFRP sheets with different strengthening schemes on such beams were studied interns of initial crack load, ultimate failure load, cracking pattern and deflection, From the experimental results it is concluded that the ultimate load carrying capacity of the R.C.C. beam with opening strengthened with GFRP sheets of different schemes were increased in the range of 3.74 to 37.41% and beams strengthened with CFRP sheets increased in the range of 9.35% to 50.50%. Among all these techniques, the strengthening with CFRP around and inside the opening was found more effective in improving the ultimate load carrying capacity of beam. This investigation helps the practicing engineers to provide an opening in the beams without reducing its load carrying capacity.