Concrete beams or slabs can be effectively retrofitted through the bonding of composite plates. Failure of the retrofitted member often occurs through delamination of the composite. Experimental investiga- tions show that unstable delamination growth at ultimate failure is preceded by…
Concrete beams or slabs can be effectively retrofitted through the bonding of composite plates. Failure of the retrofitted member often occurs through delamination of the composite. Experimental investiga- tions show that unstable delamination growth at ultimate failure is preceded by material damage along a signifi- cant part of the beam/composite interface. It is hence appropriate to analyze the problem with a non-linear fracture mechanics approach, where the delamination is treated as a fictitious interfacial crack, and interfacial damage is modelled using a softening shear stress vs slip ('ts - s) relation at the crack wake. In this paper, a combined experimental/numerical approach is developed to obtain the ('ts - s) relation at the interface. Repre- sentative experimental results are presented to illustrate the novel approach. From our results, the softening behaviour exhibits a sharp drop followed by more progressive weakening, indicating sudden loss of cohe- sion/bond, followed by gradual decrease in interfacial friction with continued sliding and damage.