Just to clear up what I read on the site,
basically I take .707*weld leg and multiply it by the weld length to get a unit Area
then calculate the moment of inertia for the weld as a line: 1/12 L^3
Tbending = M.y/I u
Tshear = P /A
Tresultant = Sqrt (τ b2 + τ s2 )
then plug into the above equations, and Presto! I can compare Tresultant to yield of material.