Failure modes for FRP wrapped cylindrical concrete columns

The effect of damage at the cohesive concrete—laminate interface on failure of FRP-reinforced concrete columns is considered. Analytical expressions, obtained for the shear stress at the interfacial bond, show that higher fabric thickness and strength result in higher interfacial shear. Hence, as fabric thickness and strength are increased, there is increased likelihood of distress in the bond due to high shear stresses. In case of damage at the interface, the nature of the interfacial bond may change and thus affect the failure load. Damage in the bond is modeled to allow transition from cohesive bond to unbonded contact, using stress-based damage initiation and energy-based damage evolution. Bond failure, resulting in damage to the surface concrete, is found to facilitate failure by fabric rupture through three distinct mechanisms.