Confinement model for high-strength concrete

A mathematical model is developed to express the stress-strain relationship of high-strength concrete confined by transverse reinforcement. The model is applicable to both normal-strength and high-strength concretes, covering a strength range between 30 and 130 MPa. It incorporates all the relevant parameters of confinement that have been observed to play important roles in column tests. These parameters include the type, volumetric ratio, spacing, yield strength, and arrangement of transverse reinforcement as well as concrete strength and section geometry. Therefore, it can be used for concrete confined by spirals, rectilinear hoops, crossties, welded wire fabric, and combinations of these reinforcements. It has been verified extensively against data obtained from column tests under concentric and eccentric loads, as well as slow and fast strain rates.