×
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

Anchor Bolts- ACI-318 App. D

Anchor Bolts- ACI-318 App. D

Anchor Bolts- ACI-318 App. D

(OP)
A question- in using Appendix D, you have the equation for breakout strength of a group of anchor bolts, which is based on the available area around the bolts.  Suppose that area essentially includes the whole concrete surface, but the breakout strength still calculates as inadequate- what then?

It seems that additional rebar tying the failure surface into the concrete would increase the strength.  Or including simultaneous downward loads.  But neither of these is included in the methodology.  Any ideas?

A related question- the Appendix is limited to 25" maximum embedment and 2" or so anchor bolts- what do you do when you go larger?

RE: Anchor Bolts- ACI-318 App. D

JStephen - The answer to both of your questions is that using rebar to tie the breakout zone into the concrete is an acceptable method and can be used when you "go larger" than the limits.  The anchor rods just need to be long enough and the reinforcing close enough to the anchor rods so that where the breakout plane crosses the reinforcing, it is fully developed above and below the breakout plane.  This almost always requires hooks on the tops of the rebar.

This method is alloweb reference within Appendix D. See commentary RD.4.2.1 (in ACI-02).  "For anchors exceeding the limitations of D.4.2.2, or for situations where geometric restrictions limit breakout capacity, or both, reinforcement oriented in teh directino of the load and proportioned to resist the total load within the breakout prism, and fully anchored on both sides of the breakout planes, may be provided instead of calculating breakout capacity."

RE: Anchor Bolts- ACI-318 App. D

Another way App D accounts for rebar is by allowing you a slightly larger resistance factor.  This is for the case that rebar is perpindicular to the bolt, not lapped with it.  It is limited, but then so was the research upon which App D is based.  

You may also lap the rebar with the bolt, as WillisV states, provided you have enough room.

When you exceed the limits of embedment or bolt diameter, you will have to find another acceptable method for design.

RE: Anchor Bolts- ACI-318 App. D

(OP)
Thanks, that's exactly what I needed.

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