×
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

Analysis of bolt groups under direct shear and torsion

Analysis of bolt groups under direct shear and torsion

Analysis of bolt groups under direct shear and torsion

(OP)
Long time lurker, first time poster.

I'm writing an algorithm at the moment to calculate the shear forces on bolts for monopole bases under a combination of pure shear and torsion. For a circular bolt pattern the equations are straightforward, but because the bolt pattern can also be square, I need a method that can handle both. There's plenty of reference material online (the attached, for example), however they only seem to handle a case of torsion in a bolt group by simplifying to M = Pe.

Imagine you have a 10 m steel utility pole with a square base plate with 8 bolts in a symmetric square pattern. At the top we have an element introducing eccentric loading at the top due to wind, leading to a combination of direct shear at the base (let's call it V) and torsion in the shaft (T) which is then resisted by the bolts in shear. With reference to the attached document, Px and Py are the components of the overall moment, M = Pe. But in the case of the utility pole, there is also V (which can be further broken down into Vx and Vy).

My statics is rusty, though what I expect is the bolt in one corner will have a higher net shear higher than the rest (as the direct shear and torsion acting together), and on the opposite corner, the bolt should have the lowest net shear (as the torsion will be acting against the direct shear). With that in mind, I was hoping you might be able to provide some clarification on which of the following is the correct modification of the the formulas in the reference document to account for this?

1. Px = Vx and Py = Vy
2. Px = Vx + T/e and Py = Vy + T/e
3. Something completely different...

I'm aware there's another method using the instantaneous centre of the bolt group, but I'd like to make sure I've grappled with this one first.

I've been stuck on this for a few hours, so any tips would be appreciated...

RE: Analysis of bolt groups under direct shear and torsion

I believe that you can use the method that you attached previously without modification. V x e = T.

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: Analysis of bolt groups under direct shear and torsion

(OP)
I was leaning that way myself, and independent verification with an analysis tool proved that to be the case. Many thanks!

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