定侧压混凝土双压疲劳损伤模型

DAMAGE MODEL FOR COMPRESSION FATIGUE LOADING OF CONCRETE WITH UNIAXIAL LATERAL CONFINEMENT

基于边界面概念和损伤力学理论,建立了一向定侧压混凝土双轴压各向异性损伤模型。加载面、边界面方程均以损伤能量释放率表示。在能量释放率空间内,由加载面与初始损伤面、边界面之间的位置描述损伤状态。通过建立累积损伤与相应循环损伤能量释放率阈值之间的关系,确定了疲劳加载中极限断裂面尺寸的变化规律,由此模拟混凝土在循环荷载作用下的刚度退化过程。结合已有的试验结果,确定了理论模型中的计算参数。经比较,理论模型预测的应力-应变数值、疲劳寿命和试验结果吻合较好。

An anisotropic damage model for concrete subjected to compression fatigue loading with constant lateral confinement is developed based on continuum damage mechanics with the concept of bounding surface. The equations of loading and bounding surfaces are described in terms with strain-energy release rate. The position of the loading surface in the energy release space between the initial and the bounding surface presents the various levels of damage states. The varying size of the limit fracture surface for fatigue loading is obtained through establishing the relation between the cumulative damage and the onset of the energy release of the cycle, which simulates the degenerative process of the stiffness of concrete under cyclic loading. The calculation parameters of the model are given according to the fatigue test results of the first author of the paper. Comparison of fatigue life indicates good agreement between the theoretical and the experimental results.