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!

*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.

Jobs

ACI 318 Appendix D and rebar development

ACI 318 Appendix D and rebar development

(OP)
A question, I have been asked to review some calculations and they are using Appendix D to calculate the development length of building pier dowels into a drilled pier. I believe that the dowels don't fit the definition of an anchor so Appendix D doesn't apply the length should be calculated using Chapter 12 "Development and Splices of Reinforcement"

RE: ACI 318 Appendix D and rebar development

A sketch would be useful to see your forces being transferred.

My answer is if they're trying to transfer the forces into additional reinforcement via lap splices or struts. If not then I agree with their choice of using Appendix D. Further, even with force transfer to other reinforcement I still would likely check appendix D to ensure there wasn't a failure of the concrete pier (but it wouldn't likely be the controlling force in determining the tensile strength developed in the bar).

For further details I hand the floor over to KootK who will undoubtedly show up.

Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries
www.americanconcrete.com

RE: ACI 318 Appendix D and rebar development

Have you checked out the HiltiRebar web program? It's geared towards almost this exact problem.

RE: ACI 318 Appendix D and rebar development

(OP)
Thanks for the quick response I should have made my problem a little clearer. The anchor rods into building pier checked per Appendix D. The question is the splice length required for the(12) - # 11 vertical dowel bars that tie the building pier cap to the 8' diameter drilled pier and splice with the (24) - #11 in the drilled pier. There is a moment on the top of the drilled pier hence there is tension in some of the vertical dowel bars

RE: ACI 318 Appendix D and rebar development

(OP)
Appendix D comes up with a development length into the drilled pier of 5'-6" and Chapter 12 7'-1"

RE: ACI 318 Appendix D and rebar development

Per ACI 318-11 D.4.2.3 the limits on embed per Appendix D is 4d to 20d.

RE: ACI 318 Appendix D and rebar development

Check out this thread for some concepts. Based on the information that you've told us, this sounds like non-contact lap splicing in excess of 6" which is often best handled with something similar to strut and tie modelling. Appendix D would not be appropriately efficient and plain development may not be sufficient.

If Appendix D were applied properly and showed enough capacity, that would probably do on it's own. Based on the calculated length, however, it doesn't sound as though it was applied properly.

Let us know how your situation may differ from the sketch below.







I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

RE: ACI 318 Appendix D and rebar development

(OP)
The sketch is very close to the actual situation, the only difference is that the (12)- #11 have hooks on top in the pier and the ties in the drilled pier seem to be light at #4 @ 23" spiral. Like I said above Chapter 12 gives a minimum of 7'-2" but based on the actual geometry I think it should be more.

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


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close