EBR VS EBROG FOR FRP STRENGTHENING OF RC SLABS: EXPERIMENTAL AND NUMERICAL MODELLING

Fiber-Reinforced Polymer (FRP) strips are often utilized with the aim to enhance the bending capacity of Reinforced Concrete (RC) slabs, in view for the latter to either resist higher loads or face aging and damage issues. However, the weak link of Externally Bonded Reinforcement (EBR) is the adhesion between the FRP strip and the concrete substrate. Several studies, both experimental and theoretical were conducted to better understand the mechanical foundations and, thus, come up with effective technological solutions capable to avoid the so-called debonding failure between FRP and concrete. In this context, Externally Bonded Reinforcement on Grooves (EBROG) emerged as a convenient technology to enhance the bonding capacity of FRP strips glued on concrete. This paper summarizes the results obtained from three experimental tests carried out on 6-m-long RC slabs strengthened in bending by FRP strips glued according to either EBR or EBROG technique. Specifically, two slabs were strengthened by an EBROG FRP strip, which in one case was also prestressed before gluing. The experimental results demonstrate the higher capacity of EBROG with respect to the conventional EBR technique and some numerical analyses show that the observed mechanical behaviour can be easily interpreted by means of reasonably simple theoretical models.
Paper 37