Theoretical Examination Of The Longitudinal Behaviour Of Embedded Rails

Zoltán Major

doi:10.1515/sjce-2015-0013

Abstract

Abstract The longitudinal behaviour of embedded rails significantly differs from that of ballasted or slab tracks with direct rail fastenings. As the ambient temperature rises and falls, rails expand and contract, thereby imposing stress on the channel and embedding compound. In the article the author presents the creation of a method that makes the calculation and the inspection of embedded rails simpler and closer to the everyday engineering mentality. The design process includes an analysis of the displacement and normal forces along a rail axis.

Highlights

The dilatational behaviour of embedded rails significantly differs from that of ballasted or slab tracks with direct rail fastenings (Ludvigh, 2002)
In the second graph there are force-displacement diagrams that are valid for ballasted tracks, slab tracks with direct rail fastenings according to EN 1991-2 and Calcada et al (2009), and for embedded rail structures with a 30 kN.mm-1.m-1/2 rail spring constant
The reason is that the Finite Element Model (FEM) calculations do not produce the value of the breathing length directly; it can only be estimated with the help of a graph, where there is no substantial change in the normal force along the length of the rail

Summary

INTRODUCTION

The dilatational behaviour of embedded rails significantly differs from that of ballasted or slab tracks with direct rail fastenings (Ludvigh, 2002). The flexible longitudinal resistance of embedded rails has been investigated by Kulcsár and Major (2014) and the properties of railway ballast by Horvát and Fischer (2011a,b) and Fischer (2011). This latter behaviour can be modelled with software that enables non-linear calculations (providing spring stiffness and limit force, see Tab. 1); and in practical calculations the flexible period can be ignored, and the plastic resistance of the ballast can be applied using well-known formulas (Lichtberger, 2005; Führer, 1978).

ANALYTICAL DESCRIPTION OF LONGITUDINAL BEHAVIOUR

Results

NEW FORMULAS FOR THE PRACTICE

CONCLUSIONS