Staad.PRO - Imperfection analysis

Hi! I have some doubts about how does Staad consider the inicial imperfections.

I have a structure that has been exposed to fire. Its mechanical properties have not been altered but there are elements that are visibly deflected.

I want to study the influence of that imperfections applying the command drift or camber.

I understand that the program considers that imperfection to calculate aditional efects on each member. But i am not sure how does it consider the magnitude of that imperfection.

If i have a column with a deflection o 40 mm and its length its 3000 mm i have to consider the value L/d = 75.

But what if each column is represented by several members in the model? If i have 2 elements, one of 2000 mm and another of 1000 mm. If i apply the L/d=75 it would be considering an inicial imperfection of 27 mm in one case and 13mm in the other one?

Which would be the correct way of considering this?

Thanks!