Stability of continuous welded rail track

Abstract

As the use of continuous welded rail (CWR) increases in track structures, derailing disasters associated with track buckling also increase in great numbers due to high compressive thermal stress. A three-dimensional CWR track model is developed in the present study to be used for extensive buckling analysis of CWR tracks subjected to temperature load. The analysis model is encoded into a special purpose program using the finite element method. The CWR track model consists of four elements: a mono-symmetric thin-walled open section beam element with 7 degrees of freedom per node to represent the rail; a solid beam-on-elastic-foundation element having 6 degrees of freedom per node to simulate the tie, including vertical and/or longitudinal ballast resistance; an elastic spring element with two nodes and zero length to stand for pad-fastener system; and spring elements for the lateral or longitudinal ballast resistances. Also, two types of significant nonlinearity are included in the track model: the geometric nonlinearity of the rail element, and the materially nonlinear resistance of the ballast. The validity of the present study is strictly verified through a series of comparative analyses with those by others. The nonlinear analysis results have shown that buckling of the track is a three-dimensional problem, and the 2-D rail–tie model and beam model overestimated the CWR track stability.