Investigation of the bond behavior for the embedded through-section FRP rod shear-strengthening method

The embedded through-section (ETS) method is a new shear strengthening technique recently developed to avoid the debonding failure that occurs with other FRP strengthening techniques such as those using externally bonded (EB) and near-surface-mounted (NSM) FRPs. The technique offers greater confinement and leads therefore to a substantial improvement in bond performance. In this study, experimental results from 13 direct-shear test specimens are reported. The influence of the following major parameters on the bond behavior of FRP-strengthened reinforced concrete beams is examined: concrete strength, quantity of epoxy adhesive, bar diameter, bar surface type, and bar bond length. The impact of these parameters is summarized in terms of the failure mode, ultimate bond force and bond force-slip relationships. The experimental results show that debonding can be avoided by providing a sufficient bar length and concrete strength. As a result, designers will be able to avoid debonding failures and to develop the full capacity of shear-strengthened beams.