Document Type : Structural Earthquake Engineering
One of the major causes of train accidents is derailment due to axial or lateral buckling of the track. This problem is more prominent in continuously welded rails (CWR), which are now very common because of their advantages of reduced noise and damage and more comfortable rides. As for the effect of earthquakes on track buckling, the axial force they induce seems to be much less than that of temperature change as well as those caused by tractive action and braking of locomotives. This does not mean that earthquakes cannot have a detrimental effect on railroad tracks. Their main cause of damage is the large reduction they may produce in the lateral resistance of ballast due to shaking of the ballast bed. This paper deals with the problem of axial and lateral buckling of CWR and the effects of earthquakes and temperature change on the stability of the track. A three-dimensional macro-element is used to model the track. A program, developed in Mathcad environment, is used to conduct a series of parametric studies. The results show that the simple sinusoidal form often used for determining buckling loads of tracks is only valid for totally homogeneous tracks, a rather rare situation. It was ascertained that the buckled shapes observed in practice are due to local inhomogeneities of the track.