Damage Model for Cyclic Loading of Concrete

A damage model for monotonic and cyclic behavior of concrete is developed. The model recognizes the tortuous nature of cracks in compression, which affects the flexibility of the material in a direction coinciding with the average plane of the cracks. An elastic potential is introduced in terms of the principal stresses and a compliance tensor dependent on the accumulated damage. Damage evolution is obtained using a loading surface and bounding surface, defined in terms of the thermodynamic force conjugates of the damage variables. The damage growth during a series of unaxial compression and cyclic tests is inferred from the amplitude attenuation of ultrasonic waveforms transmitted laterally through the specimen while the tests are in progress. The behavior of concrete under compression, tension, biaxial loading and cycling, and damage growth under both monotonic and cyclic loading are found to be predicted well by the proposed theory.