Plate to round HSS connection - Punching shear inequality in AISC 360-10 3

[SuG89]

Hello,

Please refer to the attached extract from AISC 360-10. I have a situation where the highlighted inequality is not met and the plate thickness cannot be changed now. Is there an acceptable way to check the round HSS punching shear limit state without using this inequality?

Regards
Su

 

[JAE]

It appears that in 360-16 this requirement for tp vs. t doesn't directly show up.
Both 360-10 and 360-16 state in Part 10 of the manual that punching shear (shear rupture) should be checked with equations 10-7a or 10-7b.

I believe your t vs. tp equation from the table in K1 is a result of these Part 10 equations but haven't worked out the flow on it.

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[JoshPlumSE]

Yes, I believe there are ways to demonstrate that this will not be an issue. Check out some of the other codes to see how they address it. AISC 2016, Canadian code, various design guides.

I never really liked the equation you mentioned because it's more capacity based (like a seismic connection). I don't know that this is really necessary for this type of connection. Probably based on rotational ductility ideas or such. So, maybe it's legit. You might be able to demonstrate that there is another failure (bolt bearing or such) that will precede HSS rupture to ensure ductility. It seems to me that for a lightly loaded connection, it should be okay to have rupture control over yield as long as you have some extra factor of safety.

 

[SuG89]

Thank you both for responding to my query!

Best regards,
Su

 

[Shu Jiang PEng SE]

Ultimate shear stress is Fu/sqrt(3)=0.6Fu and shear yield stress is Fy/sqrt(3)=0.6Fy. The formula k1-3 is to guarantee the configuration of the connection geometry to ensure that the chord shear yield stress is larger than the plate ultimate shear stress.
You can calculate the maximum allowable plate thickness per formula k1-3, then use the calculated maximum “tp” instead of the real “tp” to check the connection capacity. I think this way you get around your problem.


—————————————————————
Shu Jiang, SE (Nevada). PE(Michigan, South Dakota), PEng (Ontario)
J&J Structural Consulting Inc.
Structural design, analysis, inspection, drawing review and stamping, and connection design

 

[SuG89]

Thank you Shu Jiang for responding to my question!

Regards,
Su