混凝土结构疲劳全过程分析方法研究

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。

Analytical method for fatigue process of concrete structures

In order to perform a comprehensive study on the fatigue process of concrete structures, a novel analysis method was proposed. In this method, fatigue degradation of concrete material was characterized by an introduced fatigue damage constitutive model. To enhance the efficiency of fatigue analysis, a speeding calculation method, namely the cycle jump method, was developed by combining the constitutive model with the nonlinear finite element method, based on which, only few loading cycles need to be calculated to gain the whole fatigue process of concrete structures. In addition, a self-adaptive accuracy controlling method was developed, in which the jumping time can be automatically adjusted based on damage evolution rate. Through the analytical method proposed in this paper, the nonlinear behaviour, especially the cracking process of concrete structures under fatigue loading, can be well predicted. A set of simulations and experimental comparisons are presented, which illustrates the effectiveness of the model and high efficiency of the numerical algorithm in the analysis of the fatigue process of concrete structure.