Steel Railroad rail as piling

[Ksquared]

Has anyone ever used steel railroad railing as a structural pile? I have a client who wants to use railing for a building foundation that our geotechnical report recommended steel piling. The cross sectional area is greater than the HP8x36 section specified, but the moment of intertia is much smaller. I worry about slenderness during driving. Any comments or expertise you can add would be much appreciated.

Kevin King, P.E.

 

[JStephen]

Can the pile-driving equipment handle a non-standard section?

 

[Ksquared]

The piling contractor claims he can, but I have not seen the equipment yet.

 

[SlideRuleEra]

If the only concern is during diving (a big if, IMHO), this sounds like a good time to use a drop hammer - easy to (manually) control the energy delivered to the pile. Most permanent pile driving specs don't allow them, but they would not allow a rail to be used as a pile either.

http://www.SlideRuleEra.net

 

[UcfSE]

Seems like the railroad rail would have a lot less surface area. How does that affect the pile capacity analysis? Is the geotech OK with this?

 

[Ksquared]

These are relatively short piles and the capacity is based on end bearing only so the reduced surface area for skin friction is not a problem.

 

[swearingen]

A few other limit states I can think of:

- Bearing at the top of the pile. You wouldn't want the tops of the rails to punch through your mat.
- Lateral loads. Make sure that your mat is taking any lateral load into the surrounding soils; those piles are worthless laterally.
- I assume there's no uplift, since you said skin friction is not an issue. If there is uplift, you have problems.
- Make darn sure the contractor knows what he's dealing with. You don't want him to order the material and once it hits the site have him balk at handling it. It will have to be handled very carefully because of its lack of bending strength.

 

[JStephen]

Just out of curiosity, is the customer wanting to buy new rail steel and use it for this? Or does he have a couple of miles of old rail that he is wanting to salvage?

If it's old rail, that does get worn and ground some on the top surface, so area properties might be somewhat less than new rail.

 

[jike]

I would be concerned about lateral buckling and/or a torsional failure during driving or after it is fully loaded. Can the soil fully prevent lateral buckling and/or a torsional failure of this unsymmetrical rail section?

 

[frogit22]

Do NOT go against the recommendations of your Geotech or you own this foundation forever.

Using this type of section for piles does not seem like a really bad idea to me.