Uniaxial Nonlinear Viscoelastic Constitutive Model for Asphalt Concrete

摘要

A uniaxial, nonlinear, viscoelastic constitutive model for asphalt concrete isrnproposed. Based on the observation that asphaltic materials exhibit linearrnviscoelasticity at small strains/stresses and nonlinear behavior at largerrnstrains/stresses, many existing models separately employ linear viscoelasticrnmodels for the former regime and plasticity or damage models for the latter. Arnmodel is proposed in this paper that deviates from this trend. It assumes thatrnasphalt can be simultaneously characterized by both linear and nonlinearrnviscoelastic models, each of which dominates during the pertinent mechanicalrnregime. By combining a nonlinear damper with a generalized Maxwell model,rnthe behavior of asphaltic materials in both linear and nonlinear ranges can bernsimulated with a single set of material parameters to cover a wide range ofrntime, temperature, and stress/strain levels. Numerical integration algorithmsrnfor strain controlled loading and a calibration method employing constantrnstrain rate test data are proposed. The model also employs the timetemperaturernsuperposition principle and damage mechanics to account forrntemperature dependency and damage evolution, respectively. Application ofrnthe model to asphalt concrete is demonstrated using experimental data fromrndisparate researchers. It is shown that the proposed constitutive model isrncapable of successfully simulating constant strain rate tests at variousrntemperatures.