STRESS-STRAIN MODEL FOR CONFINED HIGH-STRENGTH CONCRETE

A stress-strain model for confined high-strength concrete has been developed and calibrated against the test results from 50 large-scale high-strength concrete tied columns tested under concentric loading. The effects of the concrete compressive strength, tie yield strength, tie configuration, transverse reinforcement ratio, tie spacing, and longitudinal reinforcement ratio are accounted for in the proposed stress-strain model. The determination of the strength and ductility of confined concrete is based on the computation of the effective confinement pressure, which depends on the stress in the transverse reinforcement at maximum strength of confined concrete, and on the effectively confined concrete area. A method is proposed to compute the stress in the transverse reinforcement at maximum strength of confined concrete.