混凝土拉-压疲劳损伤模型及其验证

DAMAGE MODEL FOR TENSION-COMPRESSION FATIGUE LOADING OF CONCRETE AND ITS VERIFICATION

基于连续损伤力学理论,提出了混凝土单轴拉-压疲劳损伤模型。模型中采用了拉和压两个边界面。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。结合作者完成的疲劳试验结果,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。

A constitutive relationship for predicting the response of concrete subjected to uniaxial tension-compression fatigue loading was established based on the continuum damage mechanics. The tension and compression bounding surfaces were employed in the formulation of the theoretical model. The equations of loading and bounding surfaces were described in strain-energy release rate. The position of the loading surface in the energy release space between the initial and the bounding surface present 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 were given according to the fatigue test results acquired by the authors. Comparison of the stress-strain and fatigue life results indicates good agreement between the theoretical model and the experimental data.