Abstract:
Concrete columns encased in carbon fiber reinforced polymer (CFRP) have been explored for usage in civil engineering constructions in recent years. This paper presents the results of a study to have better understanding of structural behavior of CHRCC wrapped by carbon fiber reinforced polymer (CFRP) sheets. The existing researches on CFRP confinement of reinforced concrete (RC) columns predominantly focuses on solid rectangular or square cross-sections, leaving a significant gap in understanding the behavior and performance of hollow circular RC columns under similar confinement. In the study, three dimensional finite element models have been presented to analyze reinforced concrete columns strengthened with CFRP composites, to evaluate the gain in performance (strength and ductility) due to strengthening, and to study the effect of the most important parameters considered. To achieve the desired objective, wrapping length of CFRP, diameter to thickness (D/t) ratio, lateral reinforcement ratio and concrete grade are considered as study parameters. A finite element model has been developed to investigate the behavior of RC circular hollow column strengthened with CFRP sheets by modeling twenty-two specimens, modeled under concentric loading. The numerical results using the (ANSYS APDL v.2024R1) were calibrated and validated with published experimental test results in the literature. The findings of the FE model and the experimental data were good similar. As a consequence, the model was found to be valid. The results of the study show that, external bonded CFRP sheets are very effective in enhancing the axial strength and ductility of the circular hollow reinforced concrete columns. Although CHRCC confined with 25% of its length by CFRP shows no significant difference in load carrying capacity, it is observed a 6.41% and 27% increment in load carrying capacity for 50 % and 100% CFRP confinement respectively. It was further observed that CFRP confinement has promising effect in strength enhancement for different variations in geometry and material.
Keywords: Nonlinear Finite Element Analysis (NLFEA), Hollow Circular Column, CFRP Confinement