Pin Bearing Capacity (Steel)

[Mohamed Maher]

Dear all,

I had one issue in the BS CODE (regarding pin design) one statement which is not clear for me and it's also in the Euro Code

when calculating bearing capacity of the pin or bending capacity of the pin it depends on if the rotation required or not. and if the pin intended to be removable or not.

and my question is the rotation mentioned in the code indicates for what and how can I determine if the rotation required or not? Kindly refer to the attached.

Best regards
Maher

 

[HTURKAK]

If the connection is designed purposely hinge ,( where the pinned connection shall rotate freely and shall not transfer moment , or the pin shall be removable ))... for analogy consider lifting shackle .

 

[hokie66]

If a pin connection is highly stressed, it is more likely to deform. Deformation of the pin and/or the bearing surface will tend to impede rotation.

 

[dhengr]

Mohamed Maher:
And, since you don’t bother to describe what the structure really is, or if the bolts/pins are intended to be removed or not, how would you expect us to respond/advise with any real specificity? The difference btwn. the two conditions in 6.5.3.3, a) or b), is that with the higher allowable bearing stress/load some bending and bearing deformation is expected in the pin or parts, and this makes it more difficult to remove the pin, when bent. Take a look at Hertz bearing stresses in any good Strength of Materials textbook, and imagine how the pin and pin plates deform under loading, and you will see the reason for the difference in the 1.5 or .8 factors, although we could argue for hours over the exact values or the logic/rationale that the code writers used to arrive at them.

 

[r13]

It looks like a pin connection in a (space) truss, if so, a) is applicable.

 

[HTURKAK]

The single bolt connection of detail 5 and cleat conn. at detail 6 implies ROTATION IS REQUIRED !! and condition (b) must be applied.

Typical situation for (rotation requirement ) is met at tension structures since the geometry of tension structure varies with loading. The compression struts need to be connected with single pin to provide rotation when needed.

 

[Agent666]

If the connection is part of some space truss then it is not required to be designed for rotation. Yes it will undergo some infinitesimal rotation to accommodate change in angle between members under deformation. But that's not the intent of the clauses related to rotation. They are typically related to reducing wear and deformation in the pin and plys that might otherwise inhibit the rotational capability of the connection if the ply fails in bearing. Typically bearing capacity is related to the ultimate strength, not the yield strength so deformation is accepted in a bolted connection to mobilise this strength as the metal piles up as connector bears on the metal face of the holes.

If it is part of some movable structure that actually rotates then you consider the condition with rotation, I'm thinking here this primarily applies to pins in mechanical devices, such as for example a bridge that might raise up to let traffic under, or something that moves as part of a wind sculpture or a children's swing and the connection at the crossbar, or similar.

The rotational requirement is not meant to apply to structures that undergo a few percentages of degree rotation in accommodating deflections in that structure.

 

[Agent666]

This thread had a pretty good discussion around the differences between pins and bolts and the reasoning for the rotation requirement if you actually have rotation

https://www.eng-tips.com/viewthread.cfm?qid=470836

 

[12345abc6ttyui67]

Also, probably not wise to post an entire drawing sheet with project / client specific details on the internet...

 

[Mohamed Maher]

THANK YOU ALL I'll read your notes and your clarifications and if i had any requirement i'll share with you again.

@random you are right that i planned for, maybe it was not cut as i planed however i tried to delete.

Thanks again

 

[Mohamed Maher]

@retired13 it's a fabric tent , tensile structure tent

 

[Mohamed Maher]

@hokie66

"high stress for pin connection" do you mean the parts and plates connected to the connection?
is there a limit for that , how can i decide if the connection is high stressed if the stress ratio for its cleats more than 0.9 for example. i mean maybe this is something variable from one to another

 

[r13]

Mohamed,

As guessed, it serving as a structural connection, for which free rotation is required, but not as critical as a pin in lifting device, or a pin in some mechanical device that tear and wear can impede its function, or endanger the operation. So, my call stands.