E.14 Stability of Rail Track

A nonlinear analysis was performed for the rail–foundation–bridge system shown in Figure E.14.1, subjected to the temperature load, rail axial braking load, and vertical load illustrated in Figure E.17.2. The results were compared with those presented by M. A. Van (1997). The nonlinearity of the applied system is confined to the ballast, while the rail and bridge are assumed to be linearly elastic. Figure E.17.2 shows the analysis model.

To simulate the spring connection at the top of the bridge, as shown in Figure E.17.3, a 2-node spring with a rigid arm and a vertical constraint was used to connect the rail and the bridge. For cases with rail axial loads (Case 1 and Case 2), there was no difference in results between modeling with a 2-node spring without a rigid arm and with a rigid arm. However, when a vertical load is applied (Case 3), it is essential to consider the condition in which the spring is connected to the top of the bridge via a rigid arm. The reason is that if a 2-node spring connecting the centroids of the rail and bridge is used, the rail’s axial deformation will not occur under a vertical load.

Figure E.14.1 Rail Track Stability Analysis

Figure E.14.2 Modeling

Figure E.14.3 Loading Condition

Figures E.14.4 through E.14.8 present the analysis results. In Figures E.14.6 through E.14.8, for the case with vertical load applied (Case 3), it can be seen that additional axial displacements and internal forces occur in the rail, along with shear forces in the ballast, due to the vertical load. In particular, it is observed that axial forces and moments are concentrated at the start and end points of the bridge.

Figure E.14.4 Case 1 Analysis Results

Figure E.14.5 Case 2 Analysis Results

Figure E.14.6 Case 3 Analysis Results (Rail Displacement)

Figure E.14.7 Case 2 Case 3 Analysis Results (Interal Force of Rail and Track)

Figure E.14.8 Case 3 Analysis Results (Rotation and Moment of Rail- Enlarged View)

Input file

  • Rail.inp

References

  1. M. A. Van (1997) Stability of Constinuous Welded Rail Track, Delft Universsity Press