Embedding pipe in concrete pier
Embedding pipe in concrete pier
(OP)
Hello,
I am a Civil PE designing a cantilevered column for a freestanding solar array. The posts will be steel pipe and the foundations will be a drilled concrete pier. The client would prefer to embed the pipe steel into the concrete rather than using a base plate. I used Enercalc's embedded pole calc for determining the depth of the piers and I have heard it is possible to use this feature to determing the required depth of embeddment for the pipe into the pier.
My question is, how can I determine the allowable passive pressure and maximum passive pressure (of concrete) for the input card? I am using f'c = 3000 psi concrete and the drilled shafts are 18" and 24" depending on the height of solar panels and size of pipe steel.
I appreciate any help offered!
-Ryan
I am a Civil PE designing a cantilevered column for a freestanding solar array. The posts will be steel pipe and the foundations will be a drilled concrete pier. The client would prefer to embed the pipe steel into the concrete rather than using a base plate. I used Enercalc's embedded pole calc for determining the depth of the piers and I have heard it is possible to use this feature to determing the required depth of embeddment for the pipe into the pier.
My question is, how can I determine the allowable passive pressure and maximum passive pressure (of concrete) for the input card? I am using f'c = 3000 psi concrete and the drilled shafts are 18" and 24" depending on the height of solar panels and size of pipe steel.
I appreciate any help offered!
-Ryan






RE: Embedding pipe in concrete pier
Mike McCann
McCann Engineering
RE: Embedding pipe in concrete pier
The ties in the concrete pile should take care of this concern, and I would fill the pipe with concrete to control the pipe sidewall buckling issue.
Mike McCann
McCann Engineering
RE: Embedding pipe in concrete pier
I can go conservative and embed the pipes the full length of the piers (6-7 ft), minus some cover, but I would like to use less pipe if possible.
Thanks again!
RE: Embedding pipe in concrete pier
RE: Embedding pipe in concrete pier
RE: Embedding pipe in concrete pier
RE: Embedding pipe in concrete pier
Simply calculate M/S, and compare it to a maximum allowable concrete stress of 0.35 x concrete compressive strength, or 1,050 psi. Of course, this will be a trial-and-error process.
You need to confine the concrete well with ties within the embedment zone... use at lease 2 or 3 ties fairly closely spaced at the top of the pier. For a little added conservatism you might want to lower the allowable concrete stress, and with 6'-7' piers 18" to 24" diameter required, I certainly wouldn't go any less than 12" emebedment. How about "embedment = pier diameter" sounds pretty good!
I don't see how you can use the enercalc program... "allowable passive" is resistance per foot of depth, and would be meaningless for what you are trying to do.
RE: Embedding pipe in concrete pier
I am detaling 3 full winds of spiral at the top of the pier, which should be more than enough developement to resist the tensile stresses, etc.