The nonlinear behavior of a rotating system with large elastic deformation subjected to harmonically varying ground disturbance has been investigated numerically. The Euler-Bernoulli beam theorem has been adopted in order to derive the partial differential equation governing the dynamics characteristics of the rotating system using extended Hamilton’s principle. Method of multiple scales has been selected in approximately finding the nonlinear dynamic characteristics of the system for possible resonance conditions. The effect of nonlinearities and other variations in the values of different parameters like amplitude of external excitation, position of disk along the span, and mass of the disk on the system performance has been investigated. The outcome from the present work will furnish a proper guidance to the designers in the vicinity of the limitation and safe range of operational speed of rotor shaft under the variation of other control parameters. © Springer International Publishing Switzerland 2015.