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RE: residential surcharge to Ret. wall

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to give a little more information, the slab will but or be cast over the top of the wall, and the wall is an exterior foundation wall with living space on the fill side.  The walls will range from 2' to about 7' tall from top of footing to slab elevation.

Joe



On Wed Jan 10 16:48 , 'Dennis Wish' sent:

I also forgot to ask what the setback is on the slab foundation to the wall. Is this a property wall with a setback to the slab or is the wall on an elevation change that occurs very close to the edge of slab. So the question is how far from the wall is the surcharge and at what elevation is the bottom of foundation on the residence in relation to the retaining wall foundation. I suspect the project occurs below the foundation of the retaining wall.

Dennis

 


From: Gerard Madden, SE [mailto:gmse4603(--nospam--at)gmail.com]
Sent: Wednesday, January 10, 2007 1:35 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: residential surcharge to Ret. wall

 

oh, a 3ft stem...

so that would mean a line load at the top of the wall of 120plf (assuming that the 45 degree projection from top of footing to underside of slab is not being carried by the soil). If you have a 1foot strip, I can't see that doing anything really to your footing.

A 3 foot wide footing is sorta big for a 3 foot tall retaining wall. But I wouldn't go smaller than 2'-6 anyway.

-g

On 1/10/07, Gerard Madden, SE <gmse4603(--nospam--at)gmail.com> wrote:

how tall is the wall again?

On 1/10/07, jrgrill(--nospam--at)cableone.net <jrgrill(--nospam--at)cableone.net > wrote:

I would agree with the calculations from vertical surcharge to horzontal load to the stem.  What I am asking is if the 40psf (vertical) live load (at the slab) should even be considered.  For instance, I have a short 3' stem with 500 plf axial load to the stem and very little passive resistance (only the thickness of the footing contributing).  By adding a 40 psf surcharge (again vertical surcharge) and being restricted to 1500 psf soil bearing, I am getting almost a 3' wide footing.

Joe



On Wed Jan 10 16:04 , 'Gerard Madden, SE' sent:

Generally it's a 1/3rd (uniform load (horizontal) on the stem) of the vertical surcharge load.

So for Fire trucks with a 300 psf live load surcharge or something, you would use a 100 psf horizontal load on the stem.

-g

On 1/10/07, jrgrill(--nospam--at)cableone.net wrote:

I am doing some foundation walls for a residence.  The floor slab is located over the heel of the wall footing.  I am looking at both a cantilever condition and a condition where the top of the wall is restrained ( the wall will need to be shored until the floor slab is cured to restrain the top of the footing).  I don't have a soils report for this residece.

Our building department allows 1500 psf soil bearing without a soils report.  Using this I am getting some pretty large footings using a 40 psf LL surcharge over the heel of the footing.  Part of the footing size comes from sliding resistance, but also from the surcharge.  Is using the surcharge correct or is it too conservative?

Thanks,

Joe Grill

 


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-gm

 


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