Fatigue performance of corroded reinforced concrete beams strengthened with CFRP sheets

• Corroded RC beams strengthened with CFRP sheets were tested.
• Fatigue Prediction Model of CFRP-strengthened corroded beams was proposed.
• Corrosion of rebars has detrimental effect on fatigue behavior of RC beams.
• CFRP-strengthening enhances flexural fatigue behavior of corroded beams.
• Stiffness, life, and strength are considered in turn in the strengthening design.

The fatigue performance of corroded reinforced concrete (RC) beams strengthened with carbon fiber-reinforced polymer (CFRP) sheets was examined in experimental and analytical studies. Eleven beams were constructed and tested, and an analytical Fatigue Prediction Model (FPM) was proposed to assess the beams’ fatigue behavior. After experimental validation, the FPM was extended to investigate the effect of steel corrosion degree, fatigue load range, and number of CFRP layers on the performance of corroded RC beams. This study demonstrates that the controlling factor for the fatigue behavior of the beams is the fatigue behavior of the corroded steel bars. Strengthening with 1- and 2-layer CFRP sheets at low and medium corrosion levels, respectively, were sufficient to increase the fatigue life, fatigue strength, and ultimate strength of the beam to near the levels of the uncorroded beams, but the stiffness might still fall below that of the uncorroded control beam under fatigue loading. Under cyclic fatigue loading, the consideration factors for the strengthening design of corroded RC beams fall in the order of stiffness, fatigue life, fatigue strength, and ultimate capacity.