i am trying to build a plane model in opensees,it's about a multistory steel frame;

but unlike normal beam,the damage link is insert into the beam end,and its section is reduced like the way of RBS;

if i want to incorporate Modified IMK or other model into my zerolength element,how can i get the parameters like elastic rotational stiffness,My from experimental data(test of monotonic and cyclic test on connection with this damage link.)

could i get some recommendation or reference?

thanks a lot:-)