循环荷载下考虑滞回效应的混凝土损伤模型

Starting from the dynamic non-linearity of materials for the seismic safety of high concrete dams, a damage constitutive model is established. Based on the experimental data, the tension and compression skeleton lines conforming to the actual deformation characteristics of concrete are selected to take into account the tensile and compressive anisotropy of materials. The skeleton lines contain softening section coefficients to adapt to the discreteness of the test results. The loading and unloading characteristic point expressions of the softening section independent of the skeleton line shape are adopted, and the unloading paths and reloading paths which can reflect the accumulation of damage are constructed by combining the characteristic points to describe the hysteretic effect of the softening section of concrete under a cyclic loading. It is suggested to set the critical value of residual strain to solve the continuous divergence due to the ratio of the residual plastic strain to the unloading strain increasing with the strain. The model transforms complex multi-axis problems into the uniaxial equivalent strain space with few calculation parameters and a simple mathematical expression. The correctness and efficiency of the model in solving non-linear problems are verified by the cyclic loading test of concrete and earthquake damage simulation of Koyna gravity dam.