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RE: Footing sliding resistance - Friction

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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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