sliding friction factor

[MikeE55]

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

 

[fattdad]

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!

 

[MikeE55]

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.

 

[fattdad]

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!

 

[msucog]

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

 

[msucog]

only one i can find on my computer (not the one i have pictured in my mind though---but it's in line)

http://isddc.dot.gov/OLPFiles/FHWA/010943.pdf

document page 99 table 5-15

 

[PEinc]

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

 

[PEinc]

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.

 

[PEinc]

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

 

[msucog]

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