×
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

Method for calculating pole foundation deptt, IBC equation 18-1

Method for calculating pole foundation deptt, IBC equation 18-1

Method for calculating pole foundation deptt, IBC equation 18-1

(OP)
Hello,
I am using IBC equation 18-1 to calculate the depth of a pole foundation. I'm comfortable with this method, although it does lead to a larger than expected pier foundation (3' diameter, 6.5' depth). Still, it's a small amount of concrete and the bulk of the cost of the construction will be the mob and setup of the drill.... so I'm not too bothered with the size.

My problem is that my design reviewer is giving me lots of push back to reduce the size by incorporate the weight of the concrete footing as a resistance to overturning and as an added resistance to lateral load due to the friction at the base. However my understanding is that the methods described in IBC 1807.3 does not account for either of those things. We've discussed this, but without any success. Perhaps I am missing something, can anyone clarify if I should incorporate the weight of the concrete into my design calcs using this method?

Notes:
- The axial load is minimal (weight of a column) in my design; it is very much a lateral load, creating a moment at the foundation.
- I've allowed for the 1/2" movement by doubling the lateral bearing pressure.

RE: Method for calculating pole foundation deptt, IBC equation 18-1

Who is the engineer here? Tell this BO, who is probably in bed with the contractor, where to go.

Mike McCann, PE, SE (WA)


RE: Method for calculating pole foundation deptt, IBC equation 18-1

Who is the "design reviewer". There is a big difference between that person being your boss or being the building official.

Bob

RE: Method for calculating pole foundation deptt, IBC equation 18-1

If the structure is required to be designed per the IBC, from the 2009 "Section 1807.3 Embedded posts and poles. Designs to resist both axial and lateral loads employing post or poles as columns embedded in earth or concrete footings in earth shall be in accordance with Sections 1807.3.1 through 1807.3.3" or per section 1807.3.2 Design criteria "...or by other methods approved by the building official."

So unless you get approval from the building official I would only use EQ 18-1 for the design.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

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