Performance of EBROG Method under Multilayer FRP Sheets for Flexural Strengthening of Concrete Beams

Abstract

Externally Bonded Reinforcement (EBR) is known as a conventional method for flexural strengthening of concrete beams with Fiber Reinforced Polymer (FRP) composites. However, concrete beams strengthened with this method are often associated with premature debonding mechanisms. Recently, a new promising method has been introduced at Isfahan University of Technology (IUT) to postpone or eliminate debonding of FRP sheets from concrete surface in concrete beams strengthened for flexure, named Externally Bonded Reinforcement On Grooves (EBROG). Experiments have shown that the probability of debonding when attached to concrete substrate using EBROG method is much lower than the EBR method; and in some cases debonding is completely eliminated. The aim of the current study is to examine the efficacy of grooving method when used under multilayer FRP sheets. For this purpose, beam specimens with dimension of 120×140×1000mm were cast and strengthened with both conventional surface preparation and EBROG method with different number of layers of FRP composite. Then, the strengthened beams were subjected to a four point flexural loading. The results showed that the EBROG method provides higher failure loads in the beams strengthened with multi FRP layers compare to those with conventional surface preparation.