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# RE: Foundation Torsion

• To: <seaint(--nospam--at)seaint.org>
• Subject: RE: Foundation Torsion
• Date: Wed, 8 Oct 2003 17:23:55 -0700

```If skin friction can be used to resist uplift and compression, I don't
see why you can't use it to resist twisting/torsion. Contact surface
area time skin friction resistance value takes care of it.

If you can engage the soil by utilizing passive pressure, that would
help. This seems difficult with a round shape that is twisting on its
own axis. Perhaps you could make a cruciform grade beam extending out a
bit near the top.

For design of the concrete itself, look at ACI for torsion design. Round
is good for that.

Can you use two piles and connect them with a pile cap or grade beam?
That would create a force couple where passive pressure of the soil
would be utilized by engaging each pile to resist half the twisting
force.

Just thinkin' out loud.

-gerard
Lodi, CA

-----Original Message-----
From: Jim Persing [mailto:jpersing(--nospam--at)FHOARCH.COM]
Sent: Wednesday, October 08, 2003 5:12 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: Foundation Torsion

If the 1000 lb load is vertical and you are developing a moment you
could use one of the formulas in the 97 UBC in Sections 1806.8.2.1 or
1806.8.2.2

Jim Persing, PE

> -----Original Message-----
> From: engineer101(--nospam--at)att.net [mailto:engineer101(--nospam--at)att.net]
> Sent: Wednesday, October 08, 2003 5:06 PM
> To: seaint(--nospam--at)seaint.org
> Subject: Foundation Torsion
>
>
> Can anyone recommend a guide for designing round foundations
> for torsion
> reactions?
>
> Example:
> 20ft cantilevered inverted 'L' shape structure with large
> end of the horizontal arm. Arm length = 10ft, torsion = 1000#
> X 10 ft =
> 10,000 ft-#. Foundtion = single round pile
>
> Arm_______________X1000#
> I
> I
> I
> I
> I
> 20ft
> I
> I
> I
> I
> IGround level
>
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