×
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

Slip Critical connection - ?

Slip Critical connection - ?

Slip Critical connection - ?

(OP)
I have a connection where a 3" long cantilevered plate is loaded 2.5" out causing a moment force on the connection point. The connection point is a round tube that sits between two other round tubes. There is one bolt that makes the connection. So the connection appears to be a pinned connection but we all know that would be unstable. So I was wondering if the engineer thought that he could make it a slip critical connection. So the moment you would be resisted by the torque requirement of the bolt to achieve the proper friction value.

The load is almost a joke at .5K giving you a moment of 1.25K*in = 1.25" couple force given a 1" inside diameter. The slip resistance on a 1" diameter bolt = 33.9K. Am I missing something, Does anyone see a problem with this approach?

RE: Slip Critical connection - ?

Your description of the problem is not clear. Does the pipe get squeezed across its diameter?

Michael.
Timing has a lot to do with the outcome of a rain dance.

RE: Slip Critical connection - ?

This would not be a "slip-critical" connection. There is insufficient contact between the faying surfaces. This is simply a hinge. Pretension of the "pin" will obviously resist rotation. But, 500# is a lot with a better moment resisting design.

www.FerrellEngineering.com
Providing fabrication and erection efficient structural design of connections. Consulting services for structural welding and bolting.

RE: Slip Critical connection - ?

What's the purpose of the detail? Is it so the plate can be fit up in the field to match some necessary angle and then clamped into place?

RE: Slip Critical connection - ?

(OP)
It is a bearing connection. The load that enduces a moment, in detail 2 is from a vertical column. This then is fit up to the pipe section in detail 1. The inside diameter is 1.06, a 1" bolt is then inserted through the pipes and torqued to requirements. So yes it is so that a fixed connection can be fit up to the column above.

Connectegr - could you tell me where I would find the requirements for the faying surface?

Thank you

RE: Slip Critical connection - ?

In your detail #2, the 3" plate, its connection to the column above, and the column itself must take the induced moment caused by the eccentric axial column load from above. Then the pinned (hinged) connection at detail #1 is just a shear connection and the pin and knuckles must be designed for this. There is no meaningful faying surface in your sketch. And, tightening the bolt will not support the eccentric load from above. You better rethink this entire detail.

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