Engineering model for seismic analysis of flexible rail-bound structures with uplift

In this paper, a highly simplified two-dimensional three-mass oscillator model is presented, which reproduces the typical behaviour of flexible structures of large mobile equipment transverse to the rail under seismic excitation. The typical rocking motion of the machine found in previous investigations, which is reproduced in the simplified analytical model, is taken into account together with the characteristic properties of the load-bearing structure of the complete model. The three-mass oscillator model is designed in such a way that it is able to provide information about uplift, rocking and tilting as a function of the model parameters and the excitation. A novel approach for the coefficient of restitution is derived, which takes into account the impact of wheel on rail and at the same time includes the stiffness of the subsoil. Also, a non-linear ground stiffness could be captured with this approach, and thus the influence of the ground could be investigated. This approach is of generic character, so it may be useful to a wide range of other engineering fields than mobile equipment as well. Structural parameters are determined for a range of bucket wheel machines and stackers, producing rocking and tilting spectra under sinusoidal excitations and generating tilting delimitations under seismic excitations. Using a numerical beam-mass model corresponding to the engineering model, the simplified multi-mass model can be validated.