Stress-strain behavior of low strength concrete cylinders confined with CFRP

Abstract EN

This paper presents results of an experimental investigation carried out to estimate the behavior of CFRP– confined low strength concrete cylinders under concentric and eccentric compression.

The experimental parameters included the number of the CFRP sheets and the eccentricity of the applied load.

16 Plain concrete cylinders with dimensions of 150x300mm are prepared, twelve CFRP fully confined concrete cylinders and four of them unconfined specimens were tested.

It is found that the CFRP can significantly increase the compressive strength and ductility of the concrete, thus unreinforced concrete members with low quality concrete can be wrapped by CFRP sheets for a highly improved behavior.

A significant decrease in confinement effect was found with presence of load eccentricity.

The strength gain for tested specimens under concentric loading for one, two and three layers of CFRP confinement were 125%, 250% and 310%, respectively compared with 85%, 200% and 280% for the specimens under eccentric loading.

The failure of the confined concrete was dominated by the rupture of CFRP sheets at an average strain much greater than the ultimate strain obtained from unconfined tests.

The ultimate strain of the specimens under concentric loading for one, two and three layers of CFRP confinement increases 675, 900 and 996 % respectively compared with 779,860 and 1113% for the specimens under eccentric loading.

Analytical expressions proposed for the compressive strength of CFRP wrapped low strength concrete, showed good agreement with experimental results.