NATURAL VIBRATION ANALYSIS OF RAIL TRACK AS A SYSTEM OF ELASTICALLY COUPLED BEAM STRUCTURES ON WINKLER FOUNDATION

An analytical model for analyzing the vertical free vibration of a rai l track is presented. The track structure is represented as a system o f elastically coupled beam structures resting on a Winkler foundation. The rail and the tie beams are described by any combination of the tw o existing beam theories, the Bernoulli-Euler type, and the Timoshenko type, while the rail is assumed to be periodically supported at discr ete points on cross-track tie beams. A generalized track element, whic h consists of a rail span (beam segment), two adjacent ties, and the c oupling spring stiffnesses, is established to discretize the track sys tem into identical units. A concept of an equivalent frequency-depende nt spring coefficient for the rail support system is introduced to for mulate the dynamic stiffness matrix of the track element. Solutions ar e provided for the natural frequencies of the track and the associated mode shapes of the rail and the ties under transversely (cross-track) symmetric vibration. The free vibration results are used to obtain th e dynamic receptance response of a typical field track and to compare them with an existing model and field experimental data.