Question

C.c. column is treated as short column if its slenderness ratio is less than

Answer 1

If your Slenderness Ratio is more than 12 then it's a long column or if it's less than 12 then it's called short column.
Long Column ( I / b ) > 12 or I/r > 40

I = effective length / r = Radius of gyration / b= Least dimension