# RE: Footing sliding resistance - Friction

• To: <seaint(--nospam--at)seaint.org>
• Subject: RE: Footing sliding resistance - Friction
• From: "Tom Barsh @ Codeware" <tom(--nospam--at)codeware.com>
• Date: Wed, 22 Jun 2005 12:24:42 -0500
```I would hate to be in a structure where the foundation experiences kinetic
frictional resistance.  ;-)

Tom Barsh, P.E.
Codeware Inc
www.codeware.com

> -----Original Message-----
> From: Eli Grassley [mailto:elig(--nospam--at)psm-engineers.com]
> Sent: Wednesday, June 22, 2005 12:17 PM
> To: seaint(--nospam--at)seaint.org
> Subject: RE: Footing sliding resistance - Friction
>
> We are talking about the *static* friction of a rigid mass against a
> surface.  Not the kinetic rolling resistance of a deformable
> object like a
> tire. That's an entirely different process of forces going on.
>
> Open up a freshman level physics textbook and look at the equation for
> static friction... F = mu * W
> That hasn't changed in well over 200 years.
>
> ~~ Eli ~~
>
> -----Original Message-----
> From: John Riley [mailto:jpriley485(--nospam--at)yahoo.com]
> Sent: Wednesday, June 22, 2005 9:47 AM
> To: seaint(--nospam--at)seaint.org
> Subject: Footing sliding resistance - Friction
>
> Hello Daryl:  I sometime read this list.  Need your
> help in understanding your response below.  I think
> the area has to do with the resistance also just as a
> tire low in area (more surface area) will provide more
> resistance that a pressures tire (car wt remain
> the same).  What you think?
> Tahir
> --------------------
>
> Static friction is not dependent on contact area.  For
> soils classified as 1, 2, 3 and 4 in '97 UBC Table
> 18-I-A, friction is the resistance mechanism and it is
> independent of the area.
>
> For soils classified as 5 in the same table, cohesion
> is the main resistence mechanism and it is dependent
> on contact area.
>
> That is my understanding.
>
> John Riley
>
>
>

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