Modeling the Linear Viscoelastic Behavior of Asphalt Concrete via Optimization Method

The main objective of the paper is to find suitable constitutive models used for describing the linear viscoelasticity (LVE) of asphalt concrete by comparative analysis of three viscoelastic models, including traditional generalized Maxwell (GM) model, fractional generalized Maxwell (FGM) model, and 2S2P1D (2 Springs, 2 Parabolic, 1 Dashpot) model. A multi-objective nonlinear optimization model was established according to the residual sum of squares of storage modulus and loss modulus from dynamic modulus test. The results of statistical analysis indicated that the fitting curves of fractional models with fewer mechanical elements and fitting parameters were much smoother in comparison with the traditional integer model with many unknown parameters. Therefore, the fractional model is more suitable to characterize the viscoelastic mechanical behavior of asphalt concrete within a wide frequency and temperature range.