Design Guide 4 Mnp Question

[PSSC]

This is more of philosophical question than technical.

AISC Design Guide 4 covers Extended end plate Moment Connections.
One of the first steps is to determine the diameter of bolts required.
After the actual diameter is determined you go up to the next available size bolt.
Later in the process the capacity of the actual available bolt is used to determine a "No prying bolt moment".
This moment is later used to size flange stiffeners and web stiffeners on the column side of the connection.
My actual required diameter is 0.53", so I would use a 5/8" bolt.
However the customer requires that all structural bolts be no less than 3/4".
If I use 3/4" diameter bolts to determine the "no prying bolt moment" the flange stiffeners are unusually large.
It is my opinion that I can use the 5/8" diameter bolts to determine the moment and continue the design process from there even if in reality I will provide 3/4" bolts.

Does this sound reasonable or am I totally off with this?

thanks

 

[dik]

Yup... it's not often that I use anything but 3/4 or M19 bolts...

Dik

 

[JoshPlumSE]

Is this a Seismic application? If so, then I'm not sure I agree. If you're looking for ductility out of the connection at the plastic capacity of the beam then it matters. If it's a wind connection then you're fine.

I should also point out that the other end plate design guide will give you a procedure for designing the connection that includes prying and thinner plates.

 

[PSSC]

Josh, Thanks for the reply. I had not thought about the seismic/ductility issue.
The connection is not governed by seismic loading but I will remember this in the future.

thanks,

 

[P1ENG]

You get to choose which method of the two you want to use: Large bolt, thin plate (prying action exists) or Small bolt, thick plate (prying action does not exist). Since you already know what bolt you want to use (large bolt) you calculate the minimum plate thickness using the prying action. You are calculating the minimum plate thickness, so a thicker plate is fine.

Juston Fluckey, SE, PE, AWS CWI
Engineering Consultant