Disturbed stress field model for reinforced concrete: Formulation

A conceptual model is presented for describing the behavior of cracked rein forced concrete elements, representing a hybrid formulation between a fully rotating crack model and a fixed crack model. The formulation described bu ilds on the concepts of the modified compression field theory, treating cra cked concrete as an orthotropic material with unique stress-strain relation ships in compression and tension. Advancements in the formulation, relative to the modified compression held theory, include a new approach to the reo rientation of concrete stress and strain fields, removing the restriction t hat they be coincident, and an improved treatment of sheer stresses on crac k surfaces. New sets of equilibrium, compatibility, and constitutive relati ons are formulated accordingly, and alternative crack slip models are discu ssed. The proposed theory is shown to yield improved simulations of respons e in specific situations where the previous formulation was found to produc e inaccuracies. This paper describes the formulation of the theory at the f undamental level.