Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 52 2 2020 04 20 Experimental investigation on RC beams strengthened with FRP sheets by drilling method Experimental investigation on RC beams strengthened with FRP sheets by drilling method 455 468 3317 10.22060/ceej.2019.14485.5669 FA Reza Morshed Yazd University / member of Scientific Board 0000-0002-0811-6409 Ali Shahi MSc. Graduate/ Yazd University Journal Article 2018 05 22 One of the most important applications of FRP sheets is the flexural strengthening of concrete beams by bonding these materials to the beam’s tensile surface. The most common problem in this strengthening method is the early de-bonding of the sheet from the surface of the concrete, which results in an early failure before the final strength of the beam is obtained. The most common method for preparing concrete surfaces for proper bonding of composite sheets is the Externally Bonded Reinforcement (EBR) method, which, in addition to environmental pollution, does not completely eliminate the problem of early de-bonding of FRP sheet. This paper examines the possibility of replacing the proposed drilling method with mounting screws instead of EBR method. In this research, ten samples of beam with dimensions of 150 × 300 × 1700 mm3 were tested under 4-point bending. The samples were tested by changing the number of layers and the method of mounting the sheets and in three samples with Simultaneous flexural and shear strengthening. Using the proposed method, the de-bonding problem was completely eliminated in all samples. The greatest increase in flexural strength was related to the sample, which, simultaneously strengthened in shear with FRP bars by NSM method. The effect of removing the bond in the middle part of the FRP sheets was also investigated. The installation without the bond of the sheets in the middle part delayed the rupture of the sheets. One of the most important applications of FRP sheets is the flexural strengthening of concrete beams by bonding these materials to the beam’s tensile surface. The most common problem in this strengthening method is the early de-bonding of the sheet from the surface of the concrete, which results in an early failure before the final strength of the beam is obtained. The most common method for preparing concrete surfaces for proper bonding of composite sheets is the Externally Bonded Reinforcement (EBR) method, which, in addition to environmental pollution, does not completely eliminate the problem of early de-bonding of FRP sheet. This paper examines the possibility of replacing the proposed drilling method with mounting screws instead of EBR method. In this research, ten samples of beam with dimensions of 150 × 300 × 1700 mm3 were tested under 4-point bending. The samples were tested by changing the number of layers and the method of mounting the sheets and in three samples with Simultaneous flexural and shear strengthening. Using the proposed method, the de-bonding problem was completely eliminated in all samples. The greatest increase in flexural strength was related to the sample, which, simultaneously strengthened in shear with FRP bars by NSM method. The effect of removing the bond in the middle part of the FRP sheets was also investigated. The installation without the bond of the sheets in the middle part delayed the rupture of the sheets. https://ceej.aut.ac.ir/article_3317_2c758933af02c0b301906f2819ae1268.pdf