VISCOELASTIC CONSTITUTIVE MODEL FOR ASPHALT CONCRETE UNDER CYCLIC LOADING

This paper presents a mechanistic approach to uniaxial viscoelastic co nstitutive modeling of asphalt concrete that accounts for damage evolu tion under cyclic loading conditions. Schapery's elastic-viscoelastic correspondence principle is applied as a means of separately evaluatin g viscoelasticity and time-dependent damage growth in asphalt concrete . The time-dependent damage growth in asphalt concrete is modeled by u sing a damage parameter based on a generalization of microcrack growth law. Internal state variable formulation was used in developing the a nalytical representation of the model. Tensile uniaxial fatigue tests were performed under the controlled-strain mode to determine model par ameters. Then, the resulting constitutive equation was used to predict the stress-strain behavior of the same materials under controlled-str ess mode. The constitutive equation proposed in this paper satisfactor ily predicts the constitutive behavior of asphalt concrete all the way up to failure under various loading conditions including different st ress-strain amplitudes, monotonic versus cyclic loadings, and differen t modes of loading.