Stress-Block Parameters for Unconfined and Confined Concrete Based on a Unified Stress-Strain Model

Equations to obtain equivalent rectangular stress-block parameters for unconfined and confined concrete are derived for rapid (hand) analysis and design purposes. To overcome a shortcoming of existing commonly used stress-strain models that are not easy to integrate, a new stress-strain model is proposed and validated for a wide range of concrete strengths and confining stresses. The efficacy of the equivalent rectangular stress-block parameters is demonstrated for hand calculations in predicting key moment-curvature results for a confined concrete column. Results are compared with those obtained from a computational fiber-element analysis using the proposed stress-strain model and another widely used existing model; good agreement between the two is observed.