Joint detail in continuously welded rail (CWR): A welded rail joint is generally arranged to be…
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Asupported directly on a sleeper
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Bsupported on a metal plate only
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Csuspended between adjacent sleepers
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Dnone of these
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Eplaced over a special chair
Answer
Correct Answer: suspended between adjacent sleepers
Explanation
Introduction / Context:Even in welded track, field welds join rail lengths. The position of a weld relative to sleepers affects local stiffness and stress concentration. Good practice avoids placing the weld directly over a support to minimize impact loads and reduce the risk of cracking.
Given Data / Assumptions:
- Standard sleeper spacing with elastic fastening systems.
- Field or flash-butt welds used to create long welded rails.
Concept / Approach:Placing the weld midspan (suspended) between two sleepers avoids the abrupt stiffness change that would occur if the weld coincided with a support. This reduces dynamic impacts and thermal stress concentration at the joint.
Step-by-Step Solution:
Consider stiffness profile of rail-on-sleeper system.Identify that support points create maxima in contact forces.Select suspended weld location to spread stresses and improve fatigue life.Verification / Alternative check:Track standards typically mark weld positions at a defined distance from sleeper centers, ensuring a suspended joint.
Why Other Options Are Wrong:
- Supported on sleeper/plate/chair: Increases stiffness discontinuity and impact, undesirable for weld longevity.
- None of these: Incorrect because a standard practice exists—suspended position.
Common Pitfalls:
- Confusing fish-plated joints (supported) with welded joints in CWR practice.
Final Answer:suspended between adjacent sleepers