Field welded moment connections-IBC 1

[JTPE]

Could someone explain their understanding of the construction requirements of a field welded moment connection for a OMF in seismic site class D between a beam flange and column flange? Specifically, how are the welds supposed to be run out/ground off at their ends to eliminate stress risers. Also, I have been told that the bottom backer bar has to be removed, the weld back gouged and a 5/16 fillet placed over the original weld. Is this requirement only for a OMF? only in class D? Why is the bottom weld different then the top weld?

Any thoughts would be appreciated.

 

[CWIC]

JTPE:
With regards to the run-off tabs, please refer to FEMA 353, 4.2.

The 5/16" fillet is the reinforcing fillet weld noted in D1.1, Figure 3.4 (TC-U4a-GF), note 7.

I recommend getting your hands on copies of FEMA 350 - 353.