Spring stiffness is to consider the column according to the cantilever member, in the top of the column to act a – unit force, calculate the side displacement caused by this displacement is the spring stiffness, unit – – generally KN / m. If there is a ring beam case, in the direction of no ring beam constraints, spring stiffness is calculated with the cantilever member, in the other direction, because the top of the column with a ring beam, so that the calculation of EI for the direction of all the columns in the sum.