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Hairpin design for drilled pier to resist horizontal shear forces

Hairpin design for drilled pier to resist horizontal shear forces

Hairpin design for drilled pier to resist horizontal shear forces

(OP)
I am trying to find reference material to design hairpins to resist horizontal shear forces for a drilled pier. The shaft is 18" diameter. The the total horizontal force I have is 16.14 kips. The only reference I have are the PIP STE05121 Anchor Bolt Design Guide and Foundation and Anchor Design Guide for Metal Buildings Systems by Alex Newman. The Foundation and Anchor Design Guide for Metal Buildings Systems book has a example on how to design hairpins, but it's for a pier in a slab on grade. My pier is not attached to any slab so I think I may have an issue with meeting the hairpin configuration shown in Newman's book. PIP has an example for vertical hairpins but not one for horizontal. Also the approach PIP takes gives larger capacity values for the hairpins compared to Foundation and Anchor Design Guide for Metal Buildings Systems by Alex Newman. Any recommendations/suggestions are appreciated.

RE: Hairpin design for drilled pier to resist horizontal shear forces

You cannot use hairpins for the lateral thrust if there's no slab to tie into.

You must then rely on the pier and pad to resist the sliding and overturning from the thrust all on their own.

RE: Hairpin design for drilled pier to resist horizontal shear forces

16.14k? That's pretty darn accurate. Hairpins are placed in a slab not a drilled pier. I don't have a copy of the book you mention, but in your case if the hairpins are not attached to a slab, what are they tied to at each end? Also, just a matter of semantics, but vertical hairpins = dowels?

RE: Hairpin design for drilled pier to resist horizontal shear forces

Are these just tension ties across to another pier?

RE: Hairpin design for drilled pier to resist horizontal shear forces

I see three options: 1) Design one drilled pier to take the force; 2) Use two piers with a capping beam, to form a rigid frame; 3) Use inclined earth anchors to resist the lateral force.

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