Damage Model for the Residual Strength of Concrete under Fatigue Biaxial Compression with Constant Confined Stress

Based on the continuum damage mechanics, an anisotropic elasto-damage model for predicting the residual strength of concrete under fatigue biaxial compression with constant confined stress is presented in this study. The model utilizes the concept of multiple bounding surfaces, with a varying size limit fracture surface defining fatigue loading. In expression of damage modulus, D is a constant which depends on the concrete strength under monotonic loading or low cyclic loading. However, in process of high-cycle fatigue, the attenuation of residual strength of concrete is larger, so D in the damage modulus expression is not a constant under high cycles. It is a variable which depends on the residual strength. The calculation parameters of the model are given according to the fatigue test results. A total of 101 specimens of plain concrete are tested under biaxial compressive fatigue loading with constant confined stress. In this test the constant confined stress and maximum stress of fatigue loading are both considered. The residual strength attenuating curves are also shown in the paper. Residual strength predictions of the model are compared with the experimental data. The residual strength predicted by the model seems to be in close agreement with results of experiment.