Advantages and disadvantages of several common damage defined methods were studied with test data of recycled concrete. Secondly, an inverted-S nonlinear fatigue damage cumulative model was proposed based on the three-phase law of fatigue damage evolution and physical meanings and ranges of its parameters were discussed. Eventually, the damage evolution and fatigue life of recycled concrete were investigated using the inverted-S damage model. The results indicate that many methods such as elastic modulus method, ultrasonic velocity method, maximum strain and residual strain methods are all able to represent the damage evolution law of recycled concrete. Among them, residual strain method is more suitable for its clear concept and consideration of fatigue initial damage. The fitting damage evolution equation is highly relevant with test data and the theoretically analyzed conclusion on the law of fatigue life of recycled concrete agrees well with the experimental result. Therefore, the inverted-S damage model is very suitable for the description of damage evolution of recycled concrete for its strong adaptability and high accuracy.%利用再生混凝土的疲劳试验结果,分析常用的几种损伤变量定义法的优缺点;其次,根据疲劳损伤的三阶段演化规律,提出倒S非线性疲劳累积损伤模型,给出材料参数的物理含义及取值范围;最后,基于倒S模型研究再生混凝土的损伤演化规律和疲劳寿命.分析结果表明,弹性模量法、超声波速法、最大应变以及残余应变法都能够反映再生混凝土的疲劳损伤演化规律,而残余应变法由于概念明确,考虑疲劳初始损伤,因此更为合适;拟合得到的损伤演化方程与试验数据高度相关,而理论分析得出的疲劳寿命的变化规律与试验结果也相一致;倒S模型涵盖了损伤演化规律的各种类型,具有适应性强、精度高的特点,适用于混凝土材料的损伤演化描述.
展开▼
