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

Pre-Loaded (Torqued) Cast in Place Concrete Anchors for API 650 and AWWA D100 flat bottomed tanks

Pre-Loaded (Torqued) Cast in Place Concrete Anchors for API 650 and AWWA D100 flat bottomed tanks

Pre-Loaded (Torqued) Cast in Place Concrete Anchors for API 650 and AWWA D100 flat bottomed tanks

(OP)
Greetings

I am evaluating revised wind load on an existing vertical storage tank using API 650 & AWWA D100. Both codes contain equations to determine the maximum bolt load and allowable tensile stress. They also specify provisions for preloading the anchor bolts to a percentage of the yield stress of the bolting material.

When assessing the anchor bolts using API 650 & AWWA D100 does one need to consider the applied preload and a reduction in the available bolt capacity?

In my experience with the AISC steel design manual, equations for bolt allowable shear and tensile loads for high strength fasteners are provided but are not as a function of applied bolt preload.

I seem to remember that the steel to steel bolted connection is extremely stiff and applied external loads to the joint has little effect on the tension in the preloaded bolt.

Does anyone have a code reference as to how to assess the change in allowable anchor capacity as a function of applied preload, or is this not normally assessed? Is a preload deduction included in the published allowable stresses for anchorage material?

Looking forward to your thoughts, thank you

RE: Pre-Loaded (Torqued) Cast in Place Concrete Anchors for API 650 and AWWA D100 flat bottomed tanks

I'm not aware of preload in API 650, just basic wrench tightened nuts. There is no need for preload, I think.

RE: Pre-Loaded (Torqued) Cast in Place Concrete Anchors for API 650 and AWWA D100 flat bottomed tanks

In AWWA, it is only the high-strength bolts that require preload, normal anchor bolts don't. That would mainly be in high seismic areas. I don't recall if API has a similar requirement or not. I would have to look into the issue a little more, though.

RE: Pre-Loaded (Torqued) Cast in Place Concrete Anchors for API 650 and AWWA D100 flat bottomed tanks

API limits the allowable anchor bolt stress the lower of its yield or 55ksi / 320MPa, with factors for each load case.

API further limits the tightening as follows: "Any anchor bolts shall be uniformly tightened to a snug fit (nuts hand tight in contact with anchor chair top plate plus maximum of 1/8 turn with wrench)"

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