×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Friction factor, wood foundation base to gravel

Friction factor, wood foundation base to gravel

Friction factor, wood foundation base to gravel

(OP)
I'm looking for a reference to determine an appropriate friction factor between a treated wood sill plate (square shape) and gravelly sand soil with no backfill restraint.

RE: Friction factor, wood foundation base to gravel

Drop your 2x10 or what ever on a sand playground and kick it lightly. It will move very easily. all you are doing is placing it on ball bearings.

RE: Friction factor, wood foundation base to gravel

(OP)
More detail:  The wood is 4x12x16" long with a concentric vertical load of 2000 lbs from a steel column / base plate.

RE: Friction factor, wood foundation base to gravel

Lumber cross grain friction factor on soil is approx 0.50.
Check Reference NAVFAC DM7.02 for other typical cases listed.Good Luck.

RE: Friction factor, wood foundation base to gravel

The DM-7 says .5 for wood on masonry.  I would use .25 to be on the safe side for soil.  I assume this is treated wood?

RE: Friction factor, wood foundation base to gravel


Cbosy

I use for rubber tire traction coefficients on sand and gravel approx. 0.3 to 0.4. My guess is wood should be a little higher,thus 0.5 is my estimate.

RE: Friction factor, wood foundation base to gravel

Lindeburg's Civil Engineering Review Manual, Third Edition, Table 10.4 says the friction angle for masonry on wood is 26 degrees.  If f = tan(26 degrees), f ~ 0.49.  I'd say friction for untreated wood on gravelly sand should be about f = 2/3 tan(35 degrees) = 0.46.  For newly treated (slippery) wood, I'd probably use even less, maybe 66% x f = 0.30.  That's just my guess.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources