Mechanical Properties and Structural Optimization of Continuous Welded Rail on Super-Long-Span Suspension Bridges for High-Speed Railway

In order to ensure driving safety and comfort, it is necessary to figure out the complex interaction between continuous welded rail (CWR) and suspension bridges for high-speed railway. A spatial finite element model for a 1092 m main span suspension bridge was established based on the bridge-track interaction theory. A specific correction method was put forward to keep the rail in a zero-stress state when just laid. Three rail expansion joint (REJ) layout schemes were proposed according to practical engineering experience. Both static and dynamic analysis methods were used to evaluate the feasibility of these schemes. The results show that the REJ should be laid at the position with a distance away from the primary beam end, and the beam with more substantial integral stiffness should be preferentially selected. For the recommended scheme, the REJ expansion reaches more than 380 mm under expansion load. The factors affecting the REJ expansion from major to minor are temperature, earthquake, rail fracture, braking, and bending load. The superposition effect of the above factors is suggested to be considered in the selection of REJ range.

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

For an open-deck steel plate girder railway bridge with rail joints, frequent damage to the bridge members and a high level of noise and vibration occur. By installing continuous welded rail (CWR) to the bridge, it is possible to reduce the noise and impact force of the bridge. However, current girder–sleeper fasteners have low lateral resistance in nature and track buckling can occur when CWR is used on such a bridge. Therefore, a new girder-sleeper fastener with proper lateral resistance to prevent CWR track buckling is needed. In this study, the lateral resistance requirements of a girder-sleeper fastener are investigated through a series of finite element (FE) analyses and parametric study. The effect of peak lateral resistance of the fastener, curve radius, girder length, and lateral displacement of girder are examined. From the analysis results, the peak lateral resistance criterion of the girder–sleeper fastener is proposed for the design of a new fastener for CWR tracks on an open-deck steel plate girder bridge.

A Review of Parameters Affecting Rail Break Gap Size Using Analytical Methods

Management of continuous welded rail (CWR) stress is critical to maintaining railroad safety. To successfully manage the stress-state of the rail, knowing the rail neutral temperature (RNT) is critical. RNT is defined as the temperature at which the net longitudinal force in the rail is zero. If the RNT is set too low/high then the rail would buckle/pull apart and create unsafe operation conditions. To reduce unsafe operating conditions, researchers have previously developed guidelines for managing RNT maintenance activities. However, there remains an opportunity to improve these guidelines given there have been 24 derailments caused by buckled track between 2009 and 2018. Therefore, a research program has been established to improve current guidelines. It is difficult to manage the stress of CWR because the RNT is difficult to quantify, and has been shown to change over time, tonnage, or as a result of maintenance (tamping, etc.). Further, rail breaks may lead to local changes in RNT, leading to the need for RNT readjustment. Current guidelines estimate prevalent RNT before a rail break/cut based on rail gap size. Therefore, as a part of a broader research program, this paper reviews an analytical method presented by Kerr that quantifies rail break gap length and identifies the roles of longitudinal track resistance and stiffness. Results indicate that plastic track displacements driven by longitudinal track resistance dominate, and the longitudinal track stiffness has limited influence. This paper also identifies limitations of this analytical approach and documents recommendations for improved models.

REASONS FOR DESTRUCTION OF CONTINUOUS WELDED RAIL TRACKS

The main reasons for occurrence of operational defects in continuous welded rail tracks, the main types of their destruction and causes of their occurrence are considered. The technologies for manufacture of the rails are analyzed, including heat treatment along the entire length of the rail, processing the ends of the rail, surface hardening and anti-flake treatment were analyzed.

INFLUENCE OF THE BALLAST RESISTANCE ON THE STABILITY OF CONTINUOUS WELDED RAIL

The article is about the issue of the influence of ballast resistance on the stability of the Continuous Welded Rail. The ballast resistance affects both the longitudinal and transverse displacements. It depends on the quality of the ballast, the degree of its compaction and contamination. The article contains an analysis of the impact of ballast resistance on the track based on the Finite Difference Method. The calculations showed that the resistance value directly affects the allowable critical force and the maximum temperature rise in the rail that does not endanger the safety of railway traffic.

Stiffness and Distance of Lateral Support Member Considering Buckling Strength of Sliding Track Panel

Recently, the concept of a Sliding Track Panel (STP) system, which allows the bridge to slide in the longitudinal direction, has been proposed for continuous welded rail method laid on long span non-ballast bridges, such as truss railway bridges. The performance of the STP system is determined based on the ability to prevent the lateral buckling of STP. This study attempts to derive the optimum interval distance and required stiffness of the lateral support member to be installed in the STP system through buckling analysis. According to the analysis, the interval distance of lateral support member, which satisfies the strength of STP, is less than 2.8 m and the rigidity is more than 800 N/mm.