Abstract: To understand the fatigue behavior of damaged RC beams strengthened with CFRP, three T-shaped beams strengthened with CFRP and one contrast beam were tested. The effects of the strengthening mode and the load level on the bending fatigue behavior of the beams were investigated. Experiment results show that, with CFRP strengthening, the width of the crack is reduced by 50.2% ～ 66%, and the development of the crack are eased, the stress of the reinforcing steel bar is reduced by 24.1% ～ 28.2%, and the stiffness of the beam is raised by 14.9% ～ 16.1%. Based on the results, an accurate model of the stiffness calculation and the SN curves are obtained. The model and the SN curves can be used as references in engineering practice. Suggestions on the fatigue design of CFRP strengthened beams are given.

Key words: civil building structure, RC beam, structure strengthening, fatigue test, carbon fiber reinforce plastic