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Rail Load Capacity

Rail Load Capacity

(OP)
I'm looking at evaluation of a portion of rail that will have an increased load capacity and am trying to determine the capacity and what factors are normally considered.  It's fortunate that the portion of rail is not curved (I think the contact areas shift).

Is there a method of calculating the wheel load capacity of a given rail section?

The wheel load would be distrbuted over a fraction of a square inch to the rail cap (terminology?) and this would be transmitted through the cap to the portion of rail section that is thinned down and the thinned portion could yield.

What shape does the loaded surface have?  Can it be square with an area of P/fy? Are there actual formulas that can be used?

Is the rail designed to be supported from tie to tie? or if an elatic support is provided by the ties, then some ties could be in an uplift condition (with a net downward loading).  Is this correct

RE: Rail Load Capacity

Go to a place where you can watch trains moving at low speed.
Watch the rail as a locomotive passes an arbitrary point.
You don't need to be particularly close.
You don't need magnification.
The ties directly under the wheels, and a few adjacent, move down.  Ties a little farther away move up with the rail, which takes a noticeable wave shape.  The wave moves with the locomotive.

The rail is not rigid.
The ties are not rigid.
The roadbed is not rigid.
The ground is not rigid.

Wait, it gets better.  The wheel contact faces have a little taper, and the rail head is crowned. ... almost always.  I'm guessing the contact patch is elliptical, and small.

There is a _lot_ of information available, some produced at government expense and therefore free.
Start at aar.com.

 

Mike Halloran
Pembroke Pines, FL, USA

RE: Rail Load Capacity

Also see trb.org.

 

Mike Halloran
Pembroke Pines, FL, USA

RE: Rail Load Capacity

(OP)
Thanks, Mike

Dik

RE: Rail Load Capacity

In Belgium, the next values are considered:
dia of the wheel = 800 mm
contact patch = elliptical shape with a surface of 1.5 cm²
the force is around 650 Mpa.

RE: Rail Load Capacity

(OP)
I also found out that some rails are rated for wheel load and diameter of wheel...

Thanks

Dik

RE: Rail Load Capacity

Review the article here:
rip.trb.org/browse/dproject.asp?n=24477
 

RE: Rail Load Capacity

(OP)
Thanks for the link...

Dik

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