Title: Localization and Confinement Efficiency in Carbon Fiber- Reinforced Plastic-Confined Materials

Author(s): Gebran N. Karam and Mazen R. Tabbara

Publication: Structural Journal

Volume: 117

Issue: 6

Appears on pages(s): 7-15

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

DOI: 10.14359/51728070

Date: 11/1/2020

Abstract:
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.