An additive strain model for fatigue-loaded concrete. In this contribution, the deformation behaviour of concrete is considered according to an additive strain model. The model assumes that under cyclic loads elastic, viscous, thermal and damage-induced strains occur in concrete. The strain components develop independently of each other as a function of the number of load cycles, the test duration and stress level. This thesis focuses on the determination of a creep-relevant stress level to estimate the viscous deformation component. The creep-relevant stress level is the stress level which causes the same viscous deformations under constant loads as under cyclic loads for the same test duration. Experimentally measured fatigue strains of concrete specimens are separated into the strain components assumed by the additive strain model. The components are evaluated and analysed individually. The investigations show new findings of the strain and material behaviour of fatigue-loaded concrete.