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为研究混凝土结构疲劳破坏的全过程,提出一种基于损伤力学的疲劳分析方法。该方法通过引入疲劳损伤本构模型以描述混凝土材料在疲劳荷载作用下的劣化过程。为提高计算效率,将本构模型与非线性有限元方法相结合,发展了一种循环跳跃式疲劳加速算法。基于该算法,结构的疲劳破坏过程可仅通过少量疲劳加载循环的计算加以推测。为保证算法精度,进一步提出基于损伤演化速率的自适应精度控制策略,使分析可根据疲劳损伤演化速率的变化自动调整加速算法的时间跳跃步长。采用该分析方法对混凝土材料与钢筋混凝土梁的疲劳破坏过程进行模拟,并与相关疲劳试验数据进行对比。结果表明:该分析方法可准确预测混凝土结构在疲劳荷载作用下的非线性行为,特别是疲劳加载过程中裂缝的产生和扩展过程;结合疲劳损伤本构模型和疲劳加速算法能够高效及准确地模拟混凝土结构的疲劳破坏全过程。
In order to study the whole process of fatigue damage of concrete structures, a fatigue analysis method based on damage mechanics is proposed. The method introduces the fatigue damage constitutive model to describe the degradation process of concrete under fatigue load. In order to improve the computational efficiency, a constitutive model and a nonlinear finite element method are combined to develop a cyclic jump fatigue acceleration algorithm. Based on this algorithm, the structure fatigue failure process can only be speculated by the calculation of a few fatigue loading cycles. In order to ensure the accuracy of the algorithm, an adaptive control strategy based on the damage evolution rate is proposed. The analysis can automatically adjust the time step of the acceleration algorithm according to the evolution of the fatigue damage evolution rate. The fatigue failure process of concrete material and reinforced concrete beam was simulated by this method and compared with the related fatigue test data. The results show that this method can accurately predict the nonlinear behavior of concrete structures under fatigue loading, especially the generation and propagation of cracks during fatigue loading. Combining fatigue damage constitutive model and fatigue acceleration algorithm can simulate efficiently and accurately The fatigue of concrete structures damages the whole process.