Generally the service level material stress-strain curves for concrete, reinforcement, and post-tensioning are utilized in the load history deflection calculations. The concrete stress-strain curves designated in the IS 456 and EC2 standards are not dependent upon the modulus of elasticity of the concrete. Since this a desirable attribute in deflection calculations and the user may want to define a custom modulus of elasticity that will be taken into account in the load history calculations, the PCA concrete stress-strain curve in the section "Concrete Stress-Strain Curves" is utilized in the load history calculations for these standards.