Fatigue behavior of reinforced concrete beams strengthened with prestressed fiber reinforced polymer

A series of experiments were conducted to investigate the fatigue damage behavior of reinforced concrete (RC) beams strengthened with prestressed fiber reinforced polymer (FRP) under three-point bending. Based on the experimental results, the fatigue failure mechanism of the strengthened beams and the propagation process of the fatigue interface cracks were presented, and an empirical formula was developed to predict the fatigue lives of such members. Moreover, a theoretical method was proposed to quantify the dynamic flexural stiffness of the strengthened beams. Based on the flexural stiffness, a fatigue accumulative damage model was established to describe the fatigue fracture process of the strengthened beams. The results show that the theoretical model is in good agreement with the experimental data.