中文摘要：

桥梁等钢筋混凝土结构在运营期所受活载为随机载荷。研究随机载荷作用下碳纤维薄板（Carbon Fiber Laminate简称CFL）片材增强钢筋混凝土构件的疲劳性能，对于采用碳纤维薄板技术加固桥梁等混凝土结构有重要的指导意义。本文通过随机载荷作用下碳纤维薄板增强RC梁的三点弯曲疲劳试验，得到了增强梁的S-N曲线和跨中挠度的演化规律，揭示了随机载荷下增强梁的疲劳破坏机理。随机载荷下碳纤维薄板增强RC梁的破坏模式包括钢筋断裂、碳纤维薄板剥离、混凝土压坏等破坏形态，疲劳破坏过程具有明显的损伤成核、稳定扩展、失稳扩展的三阶段发展规律。

英文摘要：

The live load is random in RC structure such as bridge. Study on the fatigue character in RC beams strengthened with Carbon Fiber Laminate（CFL） can be the very important guides in the use of carbon fiber laminate technology to strengthen RC structure as bridges. Three-point bending experiments of carbon fiber laminate strengthened RC beams under random loads were performed. The S-N curve is obtained and history of midspan flexibility of strengthened beams was recorded. Then fatigue failure mechanism of CFL strengthened RC beams was studied. The failure modes of strengthened beams under cycle loads include steel bars fracture, carbon fiber laminate debonding from concrete and concrete cracking. And their fatigue failure process shows evident three stages of damage nucleation, steady expansion and failure.