×
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

Drilled Piers Axial Compression Criteria

Drilled Piers Axial Compression Criteria

Drilled Piers Axial Compression Criteria

(OP)
If the soil bearing is high enough, one could encounter a situation where the pier will not fail the soil in bearing before is surpasses the Pallow obtained from treating the pier as a concrete compression member 0.8Φ[0.85Asf'c(Ag-As)+AsFy]. Is column axial failure a factor in drilled pier design or does the surrounding soil somehow make that a moot point?

RE: Drilled Piers Axial Compression Criteria

Most of the time, column axial failure of a drilled pier is not an issue because although the surrounding soil may not have adequate bearing capacity, it usually has enough lateral capacity to "brace" the pier against buckling failure. The exception to this is if you are drilling through really poor soil, like topsoil.

RE: Drilled Piers Axial Compression Criteria

I'm pretty sure I've never encountered a situation like that. Almost always (with a compression only pile) you will wind up with the pile exceeding its allowable skin friction + end bearing capacity before a strength issue arises in the pile (as far as reinforcement goes). An exception might be piles socketed into bedrock.

RE: Drilled Piers Axial Compression Criteria

Structural strength of the pile can be a limiting factor if it is founded in high-strength rock. I have seen a PDA test result that indicated crushing of the toe of the pile.

RE: Drilled Piers Axial Compression Criteria

Even in high strength rock, bored piles are not realistically designed for that high stress. Who would design a pile for 25 MPa, or for that matter 32 MPa, ultimate bearing? Rock is just not that consistent.

Because we only tend to use a fraction of the concrete column capacity, it is usual to reduce the pile reinforcement from 1%Ag minimum as for columns to 0.5%.

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