FR Moment Connection Question

[zrck99]

I have been tasked with providing capacities for various connections in a fabrication set of drawings. I had nothing to do with the initial design and am merely stating what the proposed connections can handle. With that being said, the proposed connection is a w beam to w column connection using a 2 bolt shear tab and upper and lower 2 bolt flange plate connections to create a moment connection.

I know that the FR moment connection section in AISC says that the flange plate must be welded to the column flange (which it is) and can be bolted or welded to the beam, but is there a minimum number of bolts or bolt rows that need to be used to make the connection rigid enough to be considered FR?

The next question is, if this is considered FR, and I am checking the tensile rupture capacity of the beam, what would the shear lag factor length, l, be for a single row of 2 bolts? Can I just take U = 1 by assuming that the load is transmitted directly to each of the cross sectional elements by the bolts?

Lastly, after I have established U, with the equation Ae = An U, do I get to use the entire beam cross sectional Area excluding the holes for the An value? For whatever reason, thinking the 1/2 the beam will be in tension while the other 1/2 is in compression makes me hesitant to use the full beam area.

Thanks in advance!

 

[weab]

I'm not at the office right now. However, make sure that you read the code commentary for the shear lag and fully restrained connection sections. I believe that they address most of your concerns.

 

[wannabeSE]

Have you looked at the Steel Construction Manual design example for bolted flange plated-fully restrained moment connections

https://www.aisc.org/globalassets/product-files-not-searched/manuals/design-examples-v14.2.pdf