RE: Footing sliding resistance - Friction

• To: <seaint(--nospam--at)seaint.org>
• Subject: RE: Footing sliding resistance - Friction
• Date: Mon, 20 Jun 2005 15:06:25 -0400
```Chris-
You may recall from physics that to get movement you must overcome the
friction force which is the coeff of friction times the deadload.  So,
forces.  Don't forget to include the weight of the soil over the heel of
the footing.

Candi Anderson, P.E.

-----Original Message-----
From: Christopher Haffner [mailto:chaffner(--nospam--at)gorge.net]
Sent: Monday, June 20, 2005 2:51 PM
To: seaint(--nospam--at)seaint.org
Subject: Footing sliding resistance - Friction

I'm having a Monday morning brain freeze and thought this was a
no-brainer
but can't find a definitive answer.

I am being told by the Geologist on a sloping (2H:1V) residential lot
that
the coefficient of friction is .45 (no units).  He is also indicating
that a
wider footing will add some needed resistance to sliding.

I don't think this is correct in that the coefficient should only depend
on
the amount of gravity (vertical) load and not on the area of the bearing
area.  Therefore, making my footings wider won't really help my sliding
problem other than to add a little more weight.  Am I thinking clearly
here?

Another question.......I will have some granular fill (varies from 1' to
6'
thick) below a basement floor slab.  I think this helps my sliding
resistance by adding weight to the system as it interfaces with the soil
below.  Since I am having the slope benched I would like to use this
resistance (weight x coef of frict).  Opinions????????

Chris

Haffner Consulting Engineering
www.haffnerconsulting.com
Office & Fax:  541-478-3052

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