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RE: residential surcharge to Ret. wall

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Joe,

I haven’t been around for a while and I finally picked up on this thread. I would not consider a live load into the surcharge unless you are considering vehicle loads similar to what CalTrans might suggest for parking areas. However, the only live load that I might give consideration to would be a portion of the snow loads in areas where they apply. With that said, the damage to a wall due to surcharges occur over time and are generally associated to dead loads.

If a soils report was done on the job, the geotechnical might require additional loads added to the back of the wall to compensate for sliding (if in a region of high seismic activity), but I would generally say that you are safe to ignore the live load conditions.

 

Dennis

 


From: jrgrill(--nospam--at)cableone.net [mailto:jrgrill(--nospam--at)cableone.net]
Sent: Wednesday, January 10, 2007 1:31 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: residential surcharge to Ret. wall

 

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 <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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