In order to better understand the interfacial fatigue behavior of concrete and fiber-reinforced polymer (FRP), bending fatigue tests were conducted on plain concrete beams strengthened with carbon FRP (CFRP) sheets under variable amplitude cyclic loading which deteriorates structural performance in actual projects more dramatically than constant amplitude loading. The test parameters were four types of loading modes including static loading, constant amplitude cyclic loading, alternating amplitude cyclic loading and incremental amplitude cyclic loading. Miner damage rule, modified Miner damage rule and Corten-Dolan cumulative damage rule were used to predict the fatigue life of specimens. The relationship between loads and deflections, the relationship between strains and cycle times and the crack propagation were analyzed. The results have shown that the fatigue life of specimens under variable amplitude cyclic loading, especially alternating one, is shorter than that of specimens under constant one, and the modified Miner damage rule is more suitable to predict fatigue life. The crack lengths on the lateral faces of beams recorded by digital image correlation (DIC) method developed more slowly than those at the bottom sides recorded by strain gauges. A proposed damage model describing the relationship between the crack lengths and fatigue life for specimens under alternating amplitude fatigue loading is consistent with the experimental results well.

中文翻译：

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CFRP片材与混凝土在变幅疲劳载荷作用下的界面特性

为了更好地了解混凝土和纤维增强聚合物（FRP）的界面疲劳行为，对碳纤维增强塑料（CFRP）板加固的素混凝土梁在变幅循环荷载下进行了弯曲疲劳试验，该梁在实际工程中会导致结构性能恶化 更多比恒幅加载显着。试验参数为静载、恒幅循环加载、交变幅循环加载和增量幅循环加载四种加载方式。Miner损伤规则、修正Miner损伤规则和Corten-Dolan累积损伤规则被用来预测试件的疲劳寿命。分析了载荷与挠度之间的关系、应变与循环次数之间的关系以及裂纹扩展。结果表明，变幅循环载荷下试件的疲劳寿命，尤其是交变载荷下试件的疲劳寿命比恒定载荷下试件的寿命短，修正Miner损伤规则更适合预测疲劳寿命。数字图像相关（DIC）方法记录的梁侧面裂纹长度比应变仪记录的底部裂纹长度发展得更慢。所提出的损伤模型描述了在交变振幅疲劳载荷下试样的裂纹长度与疲劳寿命之间的关系，与实验结果很好地吻合。修正后的 Miner 损伤规则更适合预测疲劳寿命。数字图像相关（DIC）方法记录的梁侧面裂纹长度比应变仪记录的底部裂纹长度发展得更慢。所提出的损伤模型描述了在交变振幅疲劳载荷下试样的裂纹长度与疲劳寿命之间的关系，与实验结果很好地吻合。修正后的 Miner 损伤规则更适合预测疲劳寿命。数字图像相关（DIC）方法记录的梁侧面裂纹长度比应变仪记录的底部裂纹长度发展得更慢。所提出的损伤模型描述了在交变振幅疲劳载荷下试样的裂纹长度与疲劳寿命之间的关系，与实验结果很好地吻合。