Effects of tensile steel bars arrangement on concrete cover separation of RC beams strengthened by CFRP sheets

This study was conducted to investigate the effect of reinforcement arrangement in strengthened RC beams on the concrete cover separation. For this purpose, 12 beam specimens with the dimensions of 250 mm × 300 mm × 2200 mm and different reinforcement ratios were prepared and tested under four-point bending. From the standpoint of the strengthening technique, the specimens were categorized into two groups: six specimens were strengthened by Externally Bonded Reinforcement (EBR) method and the other six specimens were strengthened using Externally Bonded Reinforcement on Grooves (EBROG). On the condition that the reinforcement ratio is constant, reducing the diameter and increasing the number of bars increased the probability of concrete cover separation. The specimens with low and medium ratios of reinforcement, in which small-diameter bars are used, demonstrated a higher load carrying capacity sustaining more deflections at mid-span before debonding of FRP sheets.