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sliding friction factor

sliding friction factor

sliding friction factor

(OP)
Is there a relationship between the angle of internal friction and the sliding friction factor?  Otherwise, how do you calculate the sliding friction factor?  

RE: sliding friction factor

There are relationships depending on whether it's cast-in-place concrete, pre-cast concrete, steel plating, etc.  The form of the relationship is essentially a percentage of the friction angle.  So if 2/3 phi is 20 degrees the friction factor would be 0.36.

Hope this helps.

f-d

¡papá gordo ain’t no madre flaca!

RE: sliding friction factor

(OP)
Sorry, I should have stated it's for cast-in-place.  Is there a reference you can recommend where the relationship is explained?  I can't find this in my old soils textbook.

RE: sliding friction factor

I'd use 2/3rds phi for cast-in-place concrete on a "coarse-grained" soil (or a frictional soil, i.e., sandy lean clay, sandy silt).

Can't recall if DM 7.1/7.2 has information on this (I'd look).

Good luck.

f-d

¡papá gordo ain’t no madre flaca!

RE: sliding friction factor

got a table in my office out of a text book but don't recall what it is off the top of my head. i remember seeing it somewhere else electronic too but my memory is failing these days. i'll look around my computer.
for cast in place and good soil 0.35-0.4 is reasonable

RE: sliding friction factor

Per Lindeburg's 3rd Edition Civil Engineering Review Manual, Page 10-23:
Condition/Friction Angle                               
1.  Concrete or masonry on clean, sound rock/35 degrees
2.  Concrete or masonry on clean gravel, gravel-sand mixtures, and coarse sand/29-31 degrees
3.  Concrete or masonry on clean fine to medium sand, silty medium to coarse sand, and silty or clayey gravel/24-29 degrees
4.  Concrete or masonry on clean fine sand, and silty or clayey fine to medium sand/19-24 degrees
5.  Concrete or masonry on fine sandy silt, and non-plastic silt/17-19 degrees
6.  Concrete or masonry on very stiff clay, and hard residual or preconsolidated clay/22-26 degrees
7.  Concrete or masonry on medium stiff clay, stiff clay, and silty clay/17-19 degrees

RE: sliding friction factor

P.S.  I usually use about 2/3 x Tan(phi) where phi is the internal friction angle of the soil or stone upon which the footing is poured.

RE: sliding friction factor

P.P.S.  Lindeburgh says it is 0.67 x phi or use his table (see above).

RE: sliding friction factor

navfac table out of fhwa in link i posted matches the numbers by peinc

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