The analysis of creep-damage processes is becoming more and more important in engineering practice due to the fact that the exploitation conditions like temperature and pressure are increasing while the weight of the structure should decrease. In the same time the safety standards are increasing too. The accuracy of the mechanical state estimation (stresses, strains and displacements) mainly depends on the introduced constitutive equations and on the chosen structural analysis model. For the first purpose an improved generalized phenomenological creep model is introduced and extended to the case of creep-damage coupling. In addition, a micromechanical-based model is discussed. For thin-walled structures under creep-damage conditions the advantages and the problems of different approaches are briefly discussed.