Traditional smeared-crack models for concrete fracture are known to suffer by stress locking (meaning here spurious stress transfer across widely opening cracks), mesh-induced directional bias, and possible instability at late stages of the loading process. The combined model keeps the anisotropic character of the rotating crack but it does not transfer spurious stresses across widely open cracks. The new model with transition to scalar damage (RC-SD) keeps the anisotropic character of the RCM but it does not transfer spurious stresses across widely open cracks.
Virgin material is modeled as isotropic linear elastic material (described by Young modulus and Poisson ratio). The onset of cracking begins, when principal stress reaches tensile strength. Further behavior is then determined by linear softening law, governed by principle of preserving of fracture energy . For large elements, the tension strength can be artificially reduced to preserve fracture energy. The transition to scalar damage model takes place, when the softening stress reaches the specified limit. Multiple cracks are allowed. The elastic unloading and reloading is assumed. In compression regime, this model correspond to isotropic linear elastic material. The model description and parameters are summarized in Tab. 20.