How to calculate the extended end plate connection with large axial loads?

[scj7665]

I have a question about beam extended end plate connection. I designed the beam connection with extended end plate (extended 1" at top and bottom flanges). For the geometry reason, there are no bolts beyond beam flanges (see attachment). I distributed the axial loads according the flange and web cross-sectional area. Is the method right? And where can I find the theory in manual or guides? Please suggestion. Thanks

 

[JoshPlumSE]

AISC has a couple of design guides for extended end plate moment connections. Your connection looks fairly similar to flush end plate connections described in Design Guide 16. I think that would be the place to start.

If that doesn't provide sufficient information, then you can check out the reference papers for the design guide (primarily the ones where Tom Murray is one of the authors). They should go into more depth about the yield line theory methodology used to develop the procedure in the design guide. My belief is your yield lines will be identical to one of the flush end plate connections and that you would therefore, be able to use those equations directly.

 

[scj7665]

Joshplum
Thank you for your explain. In the flush moment end plate or extended end plate moment connection, the axial loads and moment will be resist by beam flanges, not beam web. My concern is if the beam web can resist part axial loads (distributed by section area) or not. If the beam web can resist part axial loads, are there some limitations for the load path (bolts, end plate, etc.)? Thanks

 

[JoshPlumSE]

The main concept of the design guides is that you take a tension force in the flanges and make sure the plates and bolts can handle that tension force. It doesn't matter whether that tension comes from a moment or an axial load So, I think you are still in good shape.

However, I believe you would also want to ensure that the web weld strength is sufficient to develop the strength of the web. I recall seeing that either in AISC358 or one of the End Plate design guides. That way, you are assured that the web will yield before the weld fractures. But, assuming that the tension force goes through the flanges should still be a conservative assumption. I know that is discussed somewhere in the one of the design guides.

 

[scj7665]

JoshPlum
Thanks.I still have two questions about the end plate connection.
1. For the flush moment end plate, how can the axial load and moment transfer to beam flange? My Our customer thought there has a question about load path for this design. They thought the axial load can be transferred to column through beam flanges only if the strength of first row bolts are greater than flange force. If not, the axial loads can't transfer to column.
2. I know it is more conservative concern that all tension force goes through beam flanges. But can distributed the tension force by web and flanges section area?

 

[JoshPlumSE]

If you read the design guide it will become more clear. You calculate the moment (or equivalent moment) demand. Then you use the formulas described in the manual to determine the limiting moment capacities of the bolt and plate arrangement. If the capacity is greater than the demand then you are okay.

The main difference when you add in axial force is just that you come up with an equivalent moment:

Meq = M + P*d/2

 

[connectegr]

I hope this is an axial loaded strut and is not intended to be a simple beam. You only mention axial load, no moment forces. If this is not a moment connection and the beam supports any shear load, you have created a fixed end moment that must be considered. This is in addition to the shear and axial load given.

Does the axial load exceed the tensile strength of the beam web? By how much?

Why connect the beam flanges to the end plate for an axial load only?

You can make the end plate extremely thick, but what about the column flange?

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