Behavior of concrete cylinders confined by carbon composite 2. Prediction of strength

The mechanical behavior of round concrete cylinders confined by a carbon-epoxy composite wrapping is analyzed concerning the increased concrete compression strength due the wrapping. It is shown that the loading trajectories in the normalized stress space fit into a single master curve for all the concrete batches and jacket thicknesses investigated. The loading paths ended at failure of the composite wrapping from the increased internal lateral pressure. The strength of the composite was determined by split-disc tests of composite rings, but the strength of composite jackets realized on concrete specimens did not reach the strength of the rings. Therefore, a coefficient of composite strength reduction was introduced. A simple formula for predicting the strength of confined concrete is derived, and a comparison with fib (fédération internationale du béton) recommendations for strength predictions is given. Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 42, No. 2, pp. 165–178, April–May, 2006.