Flexural Members with Confined Concrete

Existing experimental evidence for the stress-strain curve for concrete confined by transverse steel hoops or spirals is examined and used to determine the moment-curvature characteristics of flexural members with confined concrete. The stress-strain curve for confined concrete is represented by a parabola up to maximum stress, a linear falling branch followed by a straight horizontal portion. The slope of the linear falling branch is found as a function of the volume and spacing of the hoop steel and the strength of the concrete. The compressive stress block parameters for flexural members with different levels of strain at the extreme compression fiber and quantities of confining steel are found from the proposed stress-strain curve. The examination of the moment-curvature characteristics of beams with confined concrete showed that the quantity of confining steel only has a significant effect on the behavior of members with a high tension steel content and a low compression steel content.