Concrete beams can be retrofitted by bonding a steel or composite plate to its bottom. The failure of such members is usually due to the delamination of the plate from the beam. Delamination can occur either at the end of…
Concrete beams can be retrofitted by bonding a steel or composite plate to its bottom. The failure of such members is usually due to the delamination of the plate from the beam. Delamination can occur either at the end of the reinforcing plate or at the location of a crack in the concrete beam. This paper will focus on the analysis of delamination initiated at the mouth of a flexural crack. When loading is applied, a flexural crack tends to open at the bottom of the beam, inducing high shear stress which may result in delamination. The increment of interfacial shear stress with applied moment is affected by many material and geometric parameters. In this study, the bridging stress in the bonded plate and the maximum interfacial shear stress ( 'tmax) are first related to the crack mouth opening. A fracture mechanics based analysis is then carried out to obtain the crack mouth opening and 'tmax for a given applied moment. Through a systematic parametric analysis, the effect of various parameters on 'tmruo which reflects the likelihood of delamination, can be deduced. It .is believed that the present analysis can provide insight into the prevention of delamination failure in retrofitted concrete beams.