Racking force on a steel railway bridge is due to
- ATractive effect of the driving wheel
- BBraking effect
- CResistance offered by the bearing to the movement at the roller end
- DLateral movement of the train when moving on a straight trackCorrect
Solution
Concept
Racking force
Step-by-step solution
1. Lateral loads on railway bridges include wind load, centrifugal force and racking force. 2. Racking force is the lateral force due to the nosing (lateral oscillation) of the train as it runs on a straight track.
Explanation
Racking force acts laterally on the rails and is caused by the side movement (nosing) of locomotives and vehicles on the track. It is taken as a lateral load on the loaded spans for the design of lateral bracing.
Shortcut
Racking = lateral (nosing). Tractive/braking = longitudinal.
Common mistake
Choosing a longitudinal effect.
Correct answer: D) Lateral movement of the train when moving on a straight track