RAM Concept calculates an "effective curvature ratio" at every cross section:

ECR = C_e / C_g

where

ECR	=	the effective curvature ratio
Ce	=	the effective cross section curvature (see calc below)
Cg	=	the gross section curvature

C_e is calculated by the approximate formula:

C_e = (k_c BSR C_g) + ((1 – BSR) C_ccs)

where

kc	=	the concrete material creep factor (often 3.35) = total strain / elastic strain
BSR	=	Branson’s Stress Ratio or Eurocode 2 Stress Ratio (see "Branson’s Stress Ratio" or "Eurocode 2 Cracking Distribution Stress Ratio")
Cccs	=	the cross section curvature considering cracking, creep and shrinkage (see "Cracked Section Analyses")

Note that if gross-section stresses are kept below the concrete tensile strength, then the effective curvature ratio will be equal to the concrete material creep factor (k_c).

If post-tensioning is considered as an internal force (not an external load) for the active design rules, then the gross-section calculations are performed with the post-tensioning primary forces added to the calculated cross section forces.

It is unusual, but possible, for the ECR value to be less than the concrete material creep factor (k_c). These cases occur if the amount of reinforcement is so large that the cracked stiffness (including concrete creep) is greater than the gross stiffness (including concrete creep).