Disturbed Stress Field Model for Reinforced Concrete: Formulation

TLDR

The model builds on the modified compression field theory, treating cracked concrete as an orthotropic material with distinct compression and tension stress‑strain behavior. The paper introduces a hybrid conceptual model that combines fully rotating and fixed crack formulations to describe cracked reinforced concrete elements at a fundamental level. The formulation advances the theory by allowing independent reorientation of stress and strain fields, improving shear stress treatment, and deriving new equilibrium, compatibility, and constit.

Abstract

A conceptual model is presented for describing the behavior of cracked reinforced concrete elements, representing a hybrid formulation between a fully rotating crack model and a fixed crack model. The formulation described builds on the concepts of the modified compression field theory, treating cracked concrete as an orthotropic material with unique stress-strain relationships in compression and tension. Advancements in the formulation, relative to the modified compression field theory, include a new approach to the reorientation of concrete stress and strain fields, removing the restriction that they be coincident, and an improved treatment of shear stresses on crack surfaces. New sets of equilibrium, compatibility, and constitutive relations are formulated accordingly, and alternative crack slip models are discussed. The proposed theory is shown to yield improved simulations of response in specific situations where the previous formulation was found to produce inaccuracies. This paper describes the formulation of the theory at the fundamental level.