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RE: Flag Pole Footings.

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Hmmmm......the 1/3 increase.  

That's always something I've always wondered about.  I know the UBC table allows this increase for allowable foundation pressure, but it seems to indicate that it cannot be applied to the lateral bearing pressure.  Especially if your already increasing the allowables by a factor of two for a system that is deflection tolerant.  

The shaking house makes sense.  I'll advise my client accordingly.

Tim Spengler SE

-----Original Message-----
From: Neil Moore [mailto:nmoore(--nospam--at)innercite.com]
Sent: Wednesday, October 23, 2002 11:15 AM
To: seaint(--nospam--at)seaint.org
Subject: Re: Flag Pole Footings.


Tim:

The first trick is to get a soil engineer to provide you with a realistic 
passive pressure.  ($$$)
Also, are you increasing the allowable passive by 1/3rd?
Are all of your pole heights the same?  If they aren't, then you'll have 
different loads going into the various heights.

One thing about houses supported on poles is that they shake.  Need to tell 
your client.

Neil Moore, S.E.
neil moore and associates



At 10:47 AM 10/23/02 -0700, you wrote:
>I'm doing a  preliminary design for some flag pole footings that will 
>support an 2000 sq. ft house.  They're non-constrained with an allowable 
>lateral load of 300 pcf (That includes the increase of 2 allowed for 1/2" 
>deflection tolerance).  My design criteria is the 1997 UBC.
>
>Everytime I've done a basic analysis on the flag pole footings just using 
>equation 6-1 of the UBC I've ended up with sizes that, in my opinion, 
>appear to be quite large.  Does anyone know of any "design tricks" that 
>could be employed to reduce these footing sizes?
>
>Thanks.
>
>Tim Spengler SE



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