Flexural Members with Confined Concrete

TLDR

Experimental evidence shows that the stress‑strain curve of concrete confined by transverse steel hoops or spirals follows a parabolic rise to peak stress, then a linear falling branch and a horizontal tail, and this curve is used to determine the moment‑curvature characteristics of flexural members. The study aims to determine the compressive stress‑block parameters for flexural members with varying strain levels at the extreme compression fiber and different amounts of confining steel, based on the proposed stress‑strain curve. The authors used the proposed stress‑strain curve to calculate the compressive stress‑block parameters for flexural members across varying strain levels and confining‑steel amounts. The slope of the linear falling branch depends on hoop‑steel volume, spacing, and concrete strength, and the moment‑curvature analysis shows that confining steel significantly affects members with high tension steel and low compression steel content.

Abstract

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.