Novel Anchoring Devices for Open Hoop Fiber Reinforcing Polymer Strips Used in the Shear Upgrade of R/C T-Beams

Abstract eng:
Shear strengthening of reinforced concrete (R/C) T-Beams can be achieved by open hoop FRP strips applied externally as transverse reinforcement. Unless these FRP strips are anchored the transfer of tensile forces developing in these strips relies solely on the interface between the FRP sheet and the concrete contact surface. In this case, the delamination (debonding) mode of failure of these FRP strips is very likely to occur, disrupting the effectiveness of such a shear strengthening scheme. Consequently, there is need to study both this debonding mode of failure as well as various forms of effective anchoring. For this purpose a number of special unit T-Beam R/C specimens were fabricated employing open hoop FRP strips with or without anchoring. One type of anchoring that was tested is based on a novel anchoring device. An alternative anchoring device was also tested employing anchors made of the same material as the open hoop FRP strips. It was demonstrated that an anchoring scheme devised by the authors can provide the necessary satisfactory transfer of forces between the FRP strip and the concrete volume of the R/C T-Beam. The special treatment of the bond surface resulted, as expected, in a considerable increase in the level of the maximum axial load that can be transferred from the unanchored CFRP strip to the concrete volume through the bond surface. On the contrary, when employing the efficient anchoring scheme, devised by the authors, the influence of the bond surface is immaterial. This is because, when an efficient anchoring scheme is employed, the transfer of tensile forces between the FRP strip and the concrete volume of the T-Beam is achieved at the limit state solely through the used anchoring scheme. The debonding of the FRP strip already occurrs at a preceding stage. An alternative anchoring scheme employing FRP anchor ropes also seems promising. The applicability of the anchoring scheme devised by the authors to successfully inhibit the debonding mode of failure for such open hoop CFRP strips employed in the shear strengthening of R/C T-Beams was further demonstrated in the laboratory employing for this purpose a prototype R/C T-Beam specimen. Shear strengthening, R/C T-beams, FRP strips, Anchoring Devices

• Export as: BibTeX | MARC | MARCXML | DC | EndNote | NLM | RefWorks
• Add to your basket