Steel Pipe Pile Foundations

[KZQuixote]

I recently was asked to provide the nominal outside dimension of a concrete filled steel pipe pile foundation. I answered: "As determined by structural design calculations." Which is incorrect. The correct answer is 8".

Can someone please point me toward this answer in the 2006 IBC?

TIA

Bill

 

[DAYWALKER]

Take a look at 1810.5.1

 

[KZQuixote]

Thanks DayWalker,

I'd seen that but was imagining that a diameter "not less than 8 inches" wouldn't limit the nominal diameter to 8". Just a case of a poorly worded question.

Thank You for your response.

Bill

 

[Mark K]

Section 1810.5 Item #1 in the 2006 IBC is talking baout temporary casing that is removed during the construction process.

I do not believe that hte IBC directly addresses the question. The answer would depend on how the pile was designed and how it is expected to act.

Would expect the concrete in the pipe to contribute little to the strength of pile, especially if the diameter is 10" or less.

 

[Phil]

. . . Would expect the concrete in the pipe to contribute little to the strength of pile, especially if the diameter is 10" or less.

If the load distributes based on the stiffness of the materials, a quick calc of an 8" OD pipe with a 1/2" wall thickness and 3000psi concrete (concrete modulus of elasticty varies with strength) has the concrete taking 26% of the load.

 

[Mark K]

I understand about the relative stiffness but in my experience most pipe piles of the smaller diameters are not designed as composite.

The diameter of the pile will need to be large enought to transfer the force into the soil. In many cases, where small diameter pipe piles are used, other considerations will result in a pipe strone enough to take all of the force.

The bottom line is that this is not an issue that you will find an answer in the code without performing calculations. Thus the original answer of KZQuixote was correct.