Single Plate Shear Connections

[SM3225]

Hey All,
Could you please throw some light onto the design principles of a single plate shear connection, often referred to a shear tabs - when axial force is travelling through beam ends.
I am working in a project wherein connection design falls into Fabricator's scope - my job is to furnish requisite member end forces to accomplish the connection design.
Notable is the fact the eccentricity between center line of the shear tab & axial load would generate an additional moment which consecutively increases the thickness of shear tab plate.
Having vetted the script (attached herewith) titled "Design of single plate shear connection - By ABOLHASSAN ASTANEH, STEVEN M. CALL AND KURT M. McMULLIN, I'm still clueless how to sensitize the Fabricator on board with regards to the inclusion of the axial load in the connection design.
Have anyone in this forum come across similar situation earlier?
Looking forward for your valued opinion.
Thanks and Regards.

 

[CANPRO]

I'm still clueless how to sensitize the Fabricator on board with regards to the inclusion of the axial load in the connection design

I don't understand what you're asking here. Typically if there is an axial force in a beam it is stated on the framing plan (whereas the design shear is typically covered in a note). But I'm not sure if that's what you're asking...are you trying to design these connections or find a clear and efficient way of specifying the design loads for the connections?

 

[SM3225]

CANPRO,
Thanks for your prompt response.
In particular, I'm involved in a project wherein connection design resides in Fabricator's scope... only I need to furnish the appropriate member end forces.
There are few cases wherein axial loads are significant, would dictate alternative connection details (for instance end plate type/ clip angle connection), but the Fabricator on board has submitted a calculation which does not take into account axial force, more precisely the same has been proportioned against the vertical end shear only. Upon approaching reply came "AISC design guides do not suggest to include ..."
Could you please let me know any AISC specific guidelines which strongly advocates the inclusion of axial load into the shear tab design.
IMHO we need to add the stresses generated due to bending and axial load while proportioning the tab.
Trust this clarifies.
Thanks & Regards.

 

[klaus.]

It look like an ordinary steel connection detail
What is the problem ??


best regards
Klaus

 

[CANPRO]

klaus, it sounds like the problem is that axial forces were specified, but not accounted for in the design.

SM3225, have you talked to the fabricator about this yet? It might have just been an oversight. Simple phone call or a note on the shop drawing review would be the first step in dealing with this. Single tab wouldn't be my first choice for significant axial loads either, but I don't know all of the details of the connection. Maybe the fabricator would rather go with a very heavy single tab plate to facilitate erection - a single tab plate is a lot easier to deal with on site than an endplate or double angles.

 

[WinelandV]

SM3225,

A few questions for you:

- did you note the required axial forces on the framing plans in the original plan set?
- did you include the connection detail for the combined axial and shear in the original plan set?

If the answer is yes to both of those, then you need to direct the fabricator to meet the contract documents.

Assuming that the answer is no to the first question, then you need to issue a revision to your drawings noting the axial load, and sending back the shop drawing review with the updated plan.

If I'm understanding your situation, it sounds like you're trying to avoid charge back for a change to the plans this far down the line. Is this a correct understanding of your situation?

 

[struct_eeyore]

Why dont you just reject the shop drawings until they fix it?

 

[JoshPlumSE]

There is a article (Modern Steel Construction) by Bo Dowswell that talks about eccentricities in horizontal brace connections. It's not exactly the same thing, but may be helpful. I believe the conclusion is that if them member is designed for this extra moment, then the connection need not be.

Also, if memory serves me correctly, one of the AISC design guides (either the HSS or the vertical brace design guide) has an example like this one. I think they add bending moment into the plate to reduce it's axial capacity.

 

[sandman21]

Your questions are not clear. If you are designing the connections you will need to include the axial and shear loading. Google "AISC Steel Construction Manual Design Examples v14.2", AISC provided solved design examples.

If your issue is that the contractor not providing the design, we need to know more about how the forces are given and who is responsible for the design. AISC 303-10 3.1.2 covers the delegation of the design of connections, it states "Data concerning the loads, including shears, moments, axial forces and transfer forces, that are to be resisted by the individual members and their connections, sufficient to allow the selection, completion, or design of the connection details while preparing the shop and erection drawings;". You are not going to find a section that states the connection design can ignore the axial loads.

 

[SM3225]

All,
Thanks for your response.
Yes have all the requisite forces are mentioned on the drawings/connection force's table, however Fabricator had missed (?) the inclusion of axial force into the connection design for the subjected connection. Of-course I could reject the shop drawings even I am already done with self assessment as to the possible alternative connection detail.
In particular I'm looking for any codal reference (AISC Specific) which contains explicit instruction regarding the same.If anyone is aware of kindly revert.
Thanks & Regards.

 

[CANPRO]

It’s not clear what reference you’re looking for. I believe someone already referenced an AISC design guide that covers this topic.

It sounds to me that you’re taking this further than necessary. The fabricator missed the axial requirement, you mark it up and return...pretty typical shop drawing review. They’re going to want to design the connection themselves to suit their election methodology.

 

[SM3225]

@ CANPRO:
Even though you're welcome in expressing your opinion - however just for your information the above referenced AISC design guide stands for either the HSS or the vertical brace I believe.
Moreover, if you think of stretching this issue unnecessarily - I beg to differ - circumstantially I'd like to reinforce my armory with the clause no/AISC design guide no etc - according to my opinion this kind of forum is aptly befitting for the same.
Long ago, I've indeed championed this topic - design of connection o me is as simple as a human breathes.
The primary objective of starting this thread is to inject into my neurotransmitters about the specific clause number/AISC design guide no.
Regards.

 

[wannabeSE]

SMS3225,
Have you looked at AISC 303, Code of Standard Practice for Steel Buildings and Bridges (

https://www.aisc.org/publications/steel-standards/#28233

)? Section 3.1.2 covers connection design requirements for Structural Engineer of Record and Fabricator. I am assuming your project specifications require the fabricator to have a licensed engineer design the connections. If so, the fabricator needs to have a qualified engineer do the design.

If I remember correctly, AISCs Seismic Design Manual has a nice example of designing a shear tab connection with axial loads for collectors.

 

[CANPRO]

The reference JoshPlum gave you may not have been for a beam connected with a single shear plate, but it did cover a single tab plate with axial loads - which is what it appears you're looking for. And I'm still not sure what you're looking for - your last post states that for you, connection design is as simple as breathing, so I would hope that have a good handle on this connection.

There is nothing wrong with expanding your knowledge, but my point is that (according to your information) you aren't responsible for this connection design...it is your responsibility to point out to the fabricator that they forgot the axial loads in their connection design. Do you have a history with this fabricator? Do you have some reason to believe they aren't capable of designing this connection?

 

[nutte]

SM3225 is looking for an AISC reference that deals with shear tabs with both shear and axial load. The connection engineer told him that AISC says you can neglect this axial load. Of course this is nonsense; SM3225 is asking for an AISC reference that states this.

AISC's Seismic Design manual, 2nd edition, contains example 8.4.2, which is a shear tab with both shear and axial load. They most definitely do not say you can ignore the axial load.

 

[CANPRO]

I missed the part where the fabricator responded stating he could neglect the axial. Seems a bit ridiculous that they would even suggest that. Its a shame you need an AISC reference to refute this; common sense says they need to design for the axial load as well.

 

[sandman21]

It's been given, three times now:

AISC 303-10 3.1.2 covers the delegation of the design of connections, it states "Data concerning the loads, including shears, moments, axial forces and transfer forces, that are to be resisted by the individual members and their connections, sufficient to allow the selection, completion, or design of the connection details while preparing the shop and erection drawings;". If you are looking for a AISC design guidance, Google "AISC Steel Construction Manual Design Examples v14.2", AISC provided solved design examples, one of then is exactly the situation you are talking about. You are also not going to find a section that states the connection design can ignore the axial loads.

 

[SM3225]

@nutte:= You've correctly interpreted what I'm actually looking for and thanks for sharing the definitive info.
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@Sandman21: Thanks for the info.
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@CANPRO: I'm working with this fabricator for the first time, already flashed red-card to them as they don't posses at the least the foggiest idea about AISC connection design principles - rather subscribed to the opinion for one member there will be one connection - it's a long history - moreover this is not the right forum to discuss. BTW Thanks for your prompt replies.
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Thank you all who'd spent their time on this topic. Let's maintain cordiality in the future in case of similar discussions.