Elimination of Debonging of FRP Strips in Shear Strengthened Beams Using Grooving Method

Abstract

One of the methods of retrofitting reinforced concrete structures is use of FRP sheets to increase the flexural and shear strength of concrete elements. Use of FRP materials is in rapid progress because of their high strength, light weight and easy installation of FRP composites. Poisson’s ratio mismatch between FRP sheets and concrete is resulted premature debonding of FRP strips. Hence, the use of ultimate strength of FRP sheets is difficult if EB (External bonded) is applied in installation of FRP. Therefore, debonding has been repeatedly reported in most experimental studies. Recent studies in Isfahan University of Technology (IUT) show that use of grooving method (GM) to attach the FRP sheet to concrete surface for flexural strengthening is much more effective compared to conventional methods. In present experimental study, small scale reinforced concrete beams were strengthened with FRP strips for shear. Comparison between the ultimate load and deflection of the test beams demonstrates that grooving method was effective and led to elimination of debonding of FRP strips used for shear strengthening.

RC members externally strengthened with FRP composites by grooving methods including EBROG and EBRIG: A state-of-the-art review

“…In the final steps of loading, the load-displacement curves of EBROG beams had a horizontal part. Accordingly, the ultimate displacement of the EBROG beams was 20.0% more than the EBR beams on average [81].…”

“…The high ability of the EBROG and EBRIG methods in postponing and eliminating the debonding phenomenon motivated researchers to consider these methods for external shear reinforcement of RC beams. Overall, eight different studies evaluated the shear strengthening of RC beams by FRP composites through EBROG and EBRIG methods [81][82][83][84][85][86][87][88]. Table A.2 presents the characteristics and results of the aforementioned tests [81][82][83][84][85][86][87][88].…”

“…Overall, eight different studies evaluated the shear strengthening of RC beams by FRP composites through EBROG and EBRIG methods [81][82][83][84][85][86][87][88]. Table A.2 presents the characteristics and results of the aforementioned tests [81][82][83][84][85][86][87][88].…”

“…Mostofinejad and Tabatabayi Kashani [81] performed the first study in external shear reinforcement of RC beams with FRP composites by EBROG method. The use of the EBROG method changed the failure mode from shear to flexural mode.…”

“…In this paper, all previous studies using the grooving method to retrofit structural members were evaluated. A total of 445 tests were performed by these studies, out of which 141 tests were for flexural strengthening of beams and slabs [44][45][67][68][69][70][71][72][73][74][75][76][77][78][79][80], 86 tests for shear strengthening of beams [81][82][83][84][85][86][87][88], 182 tests for strengthening columns [89][90][91][92][93][94][95][96][97][98][99][100][101][102][103][104][105], and 36 tests for strengthening beam-column joints [106][107][108][109][110][111][1...…”