Gebran N. Karam and Mazen R. Tabbara



An experimental and numerical investigation of stress-strain response, hoop strain variation, and localization of carbon fiber-reinforced composite (CFRP) confined cylinders of polypropylene and sand was carried out.

The results were used to interpret the stress-strain response of CFRP-confined concrete and to clarify the failure mechanism of CFRP-wrapped concrete columns. It is shown that failure localization in the concrete core on discrete shear planes results in a failure mechanism that causes non-uniform hoop stresses along the height of the cylinders due to the movement of rigid wedges.

Local hoop stress concentrations are shown to be the cause of fiber-reinforced plastic (FRP) premature failure. The numerical finite element model using a calibrated Mohr-Coulomb constitutive law successfully captured the experimental results.

The stress-strain response of confined concrete is similar to that of a cohesive material until localization of failure, at which point the frictional response takes over. The confinement efficiency of FRP-wrapped concrete can be estimated using the proposed numerical approach instead of experimental calibrations.



carbon fiber-reinforced plastic (CFRP) wraps; confined concrete cylinders; confinement effectiveness; frictional-cohesive material; localization; Mohr-Coulomb; strain efficiency; stress-strain response