This thesis deals with a phenomenological continuum damage model to describe the damage behavior of concrete. The micromechanically motivated, anisotropic damage model can simulate the elastic-damage material behavior during both material hardening and softening. The kinematics is based on an initial and a current configuration as well as a fictitious elastically unloaded intermediate configuration. This kinematics leads to the additive decomposition of the strains into an elastic and a damage part. An elastic potential function is introduced to consider the effect of damage on the elastic material behavior including the decrease of the elastic material properties. The onset of damage is described by a damage condition, while the irreversible strains are characterized by a non-associated damage rule. Since the damage behavior of concrete is load-dependent, the basic constitutive equations are also dependent on stress state. The proposed damage model is implemented in a finite element software. The "damage predictor - elastic corrector"-method is used for the numerical integration of the rate equations. Furthermore the consistent tangent modulus is introduced. The identification of the stress-state-dependent material parameters of the continuum damage model is based on uniaxial and biaxial experiments under monotonic and cyclic loading from the literature and corresponding numerical simulations. The execution of own experiments under complex stress states, which were recorded with a digital image correlation system, lead both to the extension and improvement of the existing material parameter functions in dependence of the stress triaxiality and to the calibration and validation of the continuum damage theory. In addition to the aggregates and the cement matrix, the composite material concrete also consists of the interface transition zone, which forms in the contact area of the other two concrete components during setting of concrete. Due to the small thickness of the interface transition zone, it is not possible to determine the material properties of this zone using conventional experimental methods. In this thesis the estimation of the material properties of the interface transition zone is proposed by comparing the strengths of two shear test specimens. One of the test specimens contains a macroscopic interface transition zone by adding two concrete parts to a basalt block, while a shear test specimen made of plain concrete of the same geometry is used as reference. The comparison of the numerical simulations with the experimental results shows that the continuum damage model can very well approximate the overall material behavior of concrete under a variety of stress states over the entire loading process.    «

This thesis deals with a phenomenological continuum damage model to describe the damage behavior of concrete. The micromechanically motivated, anisotropic damage model can simulate the elastic-damage material behavior during both material hardening and softening. The kinematics is based on an initial and a current configuration as well as a fictitious elastically unloaded intermediate configuration. This kinematics leads to the additive decomposition of the strains into an elastic and a damage p...    »