Empirical FRP-Concrete Bond Strength Model for Externally Bonded Reinforcement on Grooves

Abstract

In recent years, the grooving method in the form of “externally bonded reinforcement on groove” (EBROG) has been introduced as an alternative method of the conventional externally bonded reinforcement (EBR) for strengthening concrete structures using fiber-reinforced polymer (FRP) materials. This paper is a first attempt to develop an FRP-concrete bond strength model based on nonlinear regression on the experimental results. The agreement of the model to the data is verified using different statistical tools and analysis of variance. One hundred and fifty-four single lap-shear tests are conducted on 136 specimens made through the EBROG method and 18 specimens through the EBR method. The design of experiments techniques in the form of response surface methodology and I-optimality criteria are used to design and optimize the test layouts. The effects of groove dimensions, concrete compressive strength, and FRP sheet width and stiffness on the EBROG bond strength and its efficiency are investigated and compared with those on similar EBR specimens. Although debonding failure is observed to occur in all of the specimens, the results obtained confirm the superiority of the EBROG over the EBR specimens, as evidenced by an average enhancement of 31% achieved in bond strength and the postponed debonding. A bond strength model for the EBROG method was proposed by modifying the well-known Chen and Teng model, originally used for EBR.