Abstract：Concrete crack highly affects load-carrying performance of reinforced concrete ( RC) beams. The dynamic vibration differential equation of the cracked concrete simply-supported beams strengthened by FRP is derived based-on the Euler-Bernoulli beam theory and Hamilton energy variation method. The equation is numerically calculated by using Galerkin method. Meanwhile, the effects of crack depth, crack location, steel reinforcement and FRP on the dynamic performance of RC simply-supported beams under single and multiple harmonic excitation loads were discussed. The results show that under external load excitations, the dynamic displacement of the beam increases with the increase of the crack depth. For the same crack depths, the crack located at the mid-span has larger effect on the beam displacement response than it is located near the beam end. In the case of resonant vibrations, the development of crack depth reduces the resonant vibration frequency. The influence of the steel reinforcement on the dynamic response of FRP repaired cracked beams is larger than that of the FRP.

Keyword：RC beam with cracks;FRP-strengthening;Galerkin method;dynamic response;