Performance of Hybrid Strengthening System for Reinforced Concrete Member Using Cfrp Composites Inside and Over Transverse Groove Technique

The use of CFRP for the strengthening of structures has been widely applied in the last decades. Most studies focused on the external bonding techniques between CFRP and the RC concrete substrates. However, premature delamination of CFRP from the concrete surface was a critical failure before reaching the ultimate capacity of fiber, which reduces the efficiency of this technique. Recently, the externally bonded reinforcement over grooves (EBOGR) and inside groove (EBRITG) method has been used as an alternative to the conventional method of externally bonded reinforcement (EB) to delay the delamination and improve the bond strength. This paper examines the improvement of the proposed hybrid strengthening system combining a layer of CFRP fabric reinforcement bonded inside a transverse grooves (EBRITG) method followed by the layers of over the grooves (EBOTGR) method for RC members, utilizing the surface area inside the grooves to anchor the CFRP against premature delamination and enhance the bonding strength. Seven RC beams were used in this program and tested in two stages. Five beams with different strengthening methods including over groove, inside groove, and hybrid system in the first stage and two beams strengthened using the hybrid system with anchorage of concrete cover for the second stage. The results indicated excellent enhancement in flexural capacity using hybrid system with anchored concrete cover by achieving increase of about 57% and 72.5% with 2 and 3 layers respectively, compared with that of over-grooves reinforcement (EBOGR) method, confirming the excellent bonding efficiency of the proposed strengthening method.