×
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

Column Anchorage into Concrete--Number of Bars

Column Anchorage into Concrete--Number of Bars

Column Anchorage into Concrete--Number of Bars

(OP)
I have a steel column baseplate that is connected to a concrete foundation with anchor bolts.  The anchor bolt nuts have corroded off and there is no way to get new nuts on the connection.  The column is one leg of a four legged radio tower and is in complete tension of about 55 kips, max load.  The best solution is to cap the existing baseplate with a concrete block that is connected to the existing foundtion using grouted rebar.  I am assuming that I will use Section 12.2.2 of ACI-318 to determine the embedment length of the bars in the existing foundation.  How many bars should be used if I am using #8 bars.  A single 60 ksi bar would give me 60 kips of capacity but I think four bars would give me the symmetry I need.  Is there a pull-out cone for each bar that I need to assume that subtracts from the full tension capacity?

Thanks.

RE: Column Anchorage into Concrete--Number of Bars

Drilled and epoxy set rebars will take less length than development length.  One #8 (area of 0.79 sq. in.) with a phi of 0.75 and 125 ksi tensile strength will suffice for 74 kips of factored load.  Over lap of pull-out cones will deduct from the strength of the embedment.  See Appendix D of ACI 318.

RE: Column Anchorage into Concrete--Number of Bars

Also, if you are dealing with a pier and not a massive footing, the top of the pier can pull off of the vertical bars in the pier--so your new bars would have to extend far enough down into the pier to develop the existing bars in the pier.

DaveAtkins

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