Unfortunately our industry suffers from a lack of universal terminology - let's stick with CAESAR terminology.

CAESAR would call this a reinforced tee. While yours is drawn as a filleted rectangle - and you can certainly run an FEA on this type of connection should you choose, for purposes of CAESAR analysis, we'd treat the reinforcement pad as a circle of a radius of half of the shorter end of your rectangle.

My original response stands.

In regards to my second response, I thought you might have instead been referring to a plate that's welded to structural steel and is e.g. under a horizontal trunnion support. Disregard it as it is now inapplicable.