Incremental Formulation of Concrete Creep under Stress History

Abstract

An incremental format of the age-dependent constitutive equation was derived by expanding the total form of the constitutive equation by using the first-order Taylor series to describe the persistent change in the creep-causing stress state as well as drying shrinkage and the development of the elastic modulus. The resulting incremental constitutive equation was defined by three basic equations for basic creep, drying shrinkage, and the development of the elastic modulus. Three types of laboratory experiments were carried out to validate the performance of the presented age-dependent constitutive equation; these included cylindrical concrete specimen tests with and without axial reinforcements and reinforced beam specimen tests. The performance of the creep model was compared with those calculated by the other age-dependent constitutive equations.