×
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

Shallow Pier Foundations

Shallow Pier Foundations

Shallow Pier Foundations

(OP)
Looking for a design resource for shallow pier foundations for very light loadings.  In the range of 4' to 6' deep and appx 12" in diameter. Something to econimically support small cabins and barns. On shallow piers can you count on any skin friction or just end bearing.  Every resource I come across is for much larger loads and diameters.

RE: Shallow Pier Foundations

If you are in a cold/winter region, the frost action of the top layers of soil will negate any skin friction...usually the top 3 to 5 feet or so is ignored anyway.

I would think the 4 to 6 ft. piers would be end bearing only.

RE: Shallow Pier Foundations

I would use end bearing only.  Skin friction increases with depth and as such, there is very little friction in the top 5 to 10 feet.  Also as they are not (I assume) driven piles, the increase in soil stress along the pier would be minimal.  I would neglect skin friction for 4 to 6 foot deep piers.  

For end bearing, I would probably use Meyerhoffs method (it is a good 'average' or 'middle of the road' approach/result)

Sorry, I don't have any links to an online website for Meyerhof's method, but it is Qpoint = Area of point x effective overburden x Meyerhof's Nq* factor for piles

and the limit is:  qlimit(kN/m2) = 50 x Nq* x tan (phi)

use whichever is lower.


Also as a side note, for dia = 1' and L = 4' your results will be close to results from typical bearing capacity formulas for shallow foundations.

RE: Shallow Pier Foundations

As geodan notes, With piers so short, you are essentially dealing with a shallow foundation.

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