Study of Intermediate Crack Debonding in Adhesively Plated Beams

Abstract

The main disadvantage of reinforced concrete beams retrofitted with steel or fiber reinforced polymer (FRP) plates adhesively bonded to the external surfaces is the premature debonding of the plates before reaching the desired strength or ductility. One of the main mechanisms of debonding failure is intermediate crack (IC) debonding, which is initiated by the formation of flexural cracks in the vicinity of the plates causing slip to occur at the plate/concrete interfaces. Much of the existing research focuses on the bond–slip relationship at the plate/concrete interface, with a lack of attention on the IC debonding behavior of flexural members. In this research, a model is described for IC debonding of plated RC beams that is based on partial interaction theory. To allow a better understanding of the IC debonding behavior of plated members, studies are carried out using the proposed model to study the effects of variations in crack spacings and rate of change of moment, and it is shown that both of these factors as well as the number of cracks in the beam can have large effects on the local behavior and the resultant strains in the plated member.