connection of member with different steel grade
 

connection of member with different steel grade
itania...you're probably over-analyzing the strain compatibility issue. compensate for differences using different section properties (most notably thickness of gusset plate)to achieve greater compatibility if it is necessary.
other than corrossion and since the connections are usually designed element pere element each part will be designed in accord with its characteristics. that is, if structural plate or angle or whatever, structural, and if thin
so i think.
it would seem to me that you could just compensate by increasing the thickness of the grade 36 splice plates. let me know if i am missing something.