Development of a Model for the Prediction of the Effects of Multiple Distinct Modes of Nonlinearity on Rail Buckling

Abstract

A model is developed herein for predicting the onset of environmentally induced buckling in rail structures. As described below, the model may be considered to be an extension of previous efforts spanning much of the twentieth century, and particularly should be considered as an extension of the three degree of freedom model presented in the CRR Report No. 2017-01 (Allen and Fry, 2017) as well as the efforts presented in the derivative M. S. Thesis (Musu 2021). Building on both previous analytic and computational solutions, a finite element model is developed for the purpose of predicting buckling as a function of the track and support structure material properties, the track and support system geometries, the applied track loading, and the initial lateral displacement within the track. Particular emphasis is placed on nonlinearity and history dependence of the track environment. The model is capable of handling multiple distinct modes of nonlinearity: geometric nonlinearity due to large deformations and track misalignment, constitutive nonlinearity due to nonlinear friction at the ballast-tie interface and due to track uplift. The resulting algorithm is deployed to solve problems demonstrating usefulness of the model.