Soldier piles using encased steel railroad rail
Soldier piles using encased steel railroad rail
(OP)
I posed this question over in the Structural Engineering forum, but it occurred to me that perhaps the retaining wall guys might have had some first hand experience with this. In short we have a contractor proposing to utilize salvaged steel railroad rail as reinforcement for drilled concrete piers in a soldier pile wall application. They have done this on several projects before with what they claim are barely any deflection, and they assume full composite action of the steel rail & concrete working together. The rail is a 132lb per yard section that is 7-1/8" deep, placed near the tension face of 36" diameter drilled piers spaced at 5' c/c. Maximum retained height above bedrock is 25'.
The biggest concern we have is the assumption of composite action, which may very well be the case, but we have not found sufficient evidence or research to support such behavior for encased steel sections with no shear connectors or reinforcement. In fact, AISC has specifically stated that encased sections in beam applications must have shear connectors (though they disclaim any application of their specifications to non-building applications). We have come across some research and some statements in Handbook of Structural Engineering Second Edition by Chen & Lui which seems to back up this practice, but current codes do not seem to bear witness.
Another way to look at it (perhaps more appropriate?) is to consider the steel rail as reinforcing steel in a traditional reinforced concrete section. However, the concern here is with bond and development length of the steel since it is essentially smooth. The contractor claims that in this case that 50% of the bond strength of deformed bars is appropriate, as studies have shown that "bond" is actually about 50/50 chemical bond & mechanical bond.
Has anyone had any experience with such an application? How have you analyzed such a section? See attached photo for a scale drawing of the proposed section.
The biggest concern we have is the assumption of composite action, which may very well be the case, but we have not found sufficient evidence or research to support such behavior for encased steel sections with no shear connectors or reinforcement. In fact, AISC has specifically stated that encased sections in beam applications must have shear connectors (though they disclaim any application of their specifications to non-building applications). We have come across some research and some statements in Handbook of Structural Engineering Second Edition by Chen & Lui which seems to back up this practice, but current codes do not seem to bear witness.
Another way to look at it (perhaps more appropriate?) is to consider the steel rail as reinforcing steel in a traditional reinforced concrete section. However, the concern here is with bond and development length of the steel since it is essentially smooth. The contractor claims that in this case that 50% of the bond strength of deformed bars is appropriate, as studies have shown that "bond" is actually about 50/50 chemical bond & mechanical bond.
Has anyone had any experience with such an application? How have you analyzed such a section? See attached photo for a scale drawing of the proposed section.





RE: Soldier piles using encased steel railroad rail
Say you stick with elastic section properties. Calculate what you would need to satisfy the horizontal shear requirement. That would give you a ballpark (Comerica outfield sized ballfield, not a cozy one like Fenway) of a bond stress between concrete and steel. See how that feels to you. It doesn't feel real good to me, but I don't have any numbers. I also don't like the uneven distribution of steel, and the shear strength on unreinforced concrete at that height.
RE: Soldier piles using encased steel railroad rail
RE: Soldier piles using encased steel railroad rail
www.PeirceEngineering.com
RE: Soldier piles using encased steel railroad rail
RE: Soldier piles using encased steel railroad rail
Mike McCann
MMC Engineering
RE: Soldier piles using encased steel railroad rail
This is a tangent wall with plain concrete plug piers, so no lagging.
We have done some additional research and decided to analyze it as a reinforced concrete section, utilizing bond stress for plain bars from the earlier ACI codes (1963 I think) to determine appropriate development length. It doesn't work for all cases the contractor is proposing (i.e. heights over 20' or so) but it works for most. I hope to be able to post more details soon when I get time.
RE: Soldier piles using encased steel railroad rail
f-d
¡papá gordo ain’t no madre flaca!
RE: Soldier piles using encased steel railroad rail
Are you referring to made in the US, or legally as in not stolen off some abandoned rail line?
RE: Soldier piles using encased steel railroad rail
For a 25ft cut, unless you are in some respectable rock at the bottom, you are looking at a rail at least 50 ft long. Do they have single pieces this long?
Do these shafts need casing? I have seen full rebar cages shift significantly in shafts during casing removal. So if these holes are cased, know that your rail WILL be located somewhere other than you want it once the casing is out. I suppose you have a shot at keeping it in the right place without casing.
Is this wall permanent or temporary?
RE: Soldier piles using encased steel railroad rail
According to CSX, there is no secondary market for railroad materials. You can't recycle it, for example. If there was a secondary market, crooks would take such "free" material at the expense of public safety. The train company is supposed to collect it all and then under chain of custody, melt it down. To see quantities of rail in the secondary market makes me consider the chain of custody of the contractor. Now I'm not suggesting that the contractor is taking his own, but it does raise a red flag to me. . .
f-d
¡papá gordo ain’t no madre flaca!
RE: Soldier piles using encased steel railroad rail
f-d - a quick google search yields results of several contractors who specialize in removing rails, and others who keep an inventory of salvaged rail. I also came across an invitation for bids from the Dept. of Energy to remove old rail lines. The request stipulated that the contractor must certify that they will not sell the rail for scrap or smelting, but that they will only sell it in its current physical form. I'm not saying your info is incorrect - just trying to get to the bottom of this. If there are potential legal issues, I would certainly want to know.