A thermodynamic constitutive model for plain concrete, and other quasi-brittle materials, is developed. The model accounts for the anisotropic... Show moreA thermodynamic constitutive model for plain concrete, and other quasi-brittle materials, is developed. The model accounts for the anisotropic damage-induced and the aging viscoelasticity of the material. The model is based on the theory of solidi cation proposed by Baºant and the continuum damage mechanics theory. The material is considered to be a viscoelastic-damageable material. The Helmholtz free energy utilized in the formulation is treated by means of the representation theorem of coupled damage-strain tensors. The model is capable of analyzing time-dependent damage (tertiary creep) under constant loading and damage due to cyclic creep. Two simple but practical examples are presented in order to illustrate the applicability of the model. The determination of the functions and constants representing the material behavior as well as any experimental companion is proposed for the continuation of the research. Ph.D. in Civil Engineering, May 2016 Show less