Suggestion for allowable additional compressive stress based on track conditions

Abstract

A continuous welded rail has immovable zones due to its structural characteristics. In an immovable zone, thermal expansion and contraction of rails are restricted when the temperature changes, thereby causing excessive axial force on the rail. When the immovable zone of the continuous welded rail is located on a bridge, additional stress and displacement occur through track–bridge interactions. Additional stress and displacement of the rail compared to the embankment area are restricted when constructing the bridge under the continuous welded rail track to prevent problems with the track–bridge interaction according to UIC 774-3R and Euro codes. According to the various codes, the maximum allowable additional compressive stress is 72 MPa, with the conditions of a curve with a radius (R) ≥ 1500 m, UIC 60 continuous welded rail (tensile strength of at least 900 MPa), ballasted track with concrete sleepers and 30 cm of deep for a well-consolidated ballast. However, the lateral resistance that has the greatest effect on track stability can depend on the conditions mentioned above. Therefore, an additional review of various track conditions is required. In this paper, an evaluation of the current criteria was performed using the minimum buckling strength calculation formula, and the allowable additional stress on the rail suggested by codes could only be used on tracks with a large lateral resistance above 18 kN/m/track. Thus, a three-dimensional nonlinear analysis model was developed and analyzed to calculate the allowable additional compressive stress considering various track conditions. According to the results of the analysis, the allowable additional compressive stress was reduced with a comparatively small lateral resistance. The freedom of design can be enhanced with respect to the parameters of various track and bridge conditions using this model.

Lateral Resistance Requirement of Girder-Sleeper Fastener for CWR Track on an Open-Deck Steel Plate Girder Bridge

“…The FE model for the CWR track on the bridge is constructed based on the modeling approach of previous research [13]. The model consists of bridge and embankment regions, as shown in Figure 7.…”

Monitoring and Evaluation of the Lateral Stability of CWR Track

“…Advantages and limitations of the analyzes and of the nondestructive methods are discussed based upon the information available in the scientific literature. An evaluation of the current criteria was performed in [28] using the minimum buckling strength calculation using a developed 3D nonlinear analysis model. The results show that the allowable additional compressive stress was reduced with a comparatively small lateral resistance.…”

Parametric Study of Additional Temperature Stresses in Continuously Welded Rails on Steel Truss Railway Bridges

“…The analysis revealed that while the temperature gradient does affect the bridge support reactions, it does not have a significant impact on the stresses in CWRs or track stability. Yun et al [18] developed a three-dimensional TBI numerical model and carried out a nonlinear analysis to calculate the permissible additional compressive stresses by considering different track conditions. According to the obtained results, it was concluded that the prescribed permissible values of additional compressive stresses should be reduced tracks having relatively small lateral resistance.…”