Continuously Welded Railroad Track
Continuously Welded Railroad Track
(OP)
How is thermo expansion taken into account with thousands of feet of continuously welded railroad track positively attached to railroad ties with spikes?
When was the last time you drove down the highway without seeing a commercial truck hauling goods?
Download nowINTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS Come Join Us!Are you an
Engineering professional? Join Eng-Tips Forums!
*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail. Posting GuidelinesJobs |
Continuously Welded Railroad Track
|
RE: Continuously Welded Railroad Track
It might appear that the eccentrical spikes might induce moment, but it is not to be forgotten that the rail is precisely continuous and will oppose entire and equal reaction at the ends. The stresses locked from temperature should remain relatively small, for the rails have to sustain the heavy loads of the wheels and braking.
RE: Continuously Welded Railroad Track
An irrelevant aside. To lessen the risk of buckling, continuously welded rail is pre-tensioned so that it will be in tension over the majority of its expected operating temperature range. A railway I was involved with recently has to cope with temperatures between about -8 and +60 degrees centigrade (18F to 140F): the rail was pre-tensioned so that its stress-free temperature was 40 degrees (104F).
RE: Continuously Welded Railroad Track
I believe that I understand your reply but I just want to clarify thru the following:
Are you saying that all expansion stresses are being accommodated by the rail material itself? In other words, is the rail possibly seeing a very very slight non-axial deformation due to the buildup of stresses at the local area in between the points of fixity (a so called wall stress build-up)?
Also, is the spike restraining all forces by the friction action between it's head and the rail surface ? What happens if you get slippage at this location????? Will the next consecutive spike fail in a domino effect or could the rail possibly fail in a non-axial direction ????
How is the friction effect of the spike on the rail enhanced so that risk of either failure (slip or rail material)is reduced ?
RE: Continuously Welded Railroad Track
RE: Continuously Welded Railroad Track
I also think if there were no joints for expansion, more rails would buckle during the hottest summer days then already do (you occasionally hear of a derailment during heat-waves).
RE: Continuously Welded Railroad Track
Of course if the expansion forces (or shortining ones) overcome friction you have one rail that is able to expand, in the extent that the standing restrictions allow. If such elongations were big, joints also need be -a problem-, or else what one needs to make is control expansion or shortening at the tie level, rather than for whole rails between joints.