In Precast/Prestressed Girder, you can select to use transformed section properties for the beam design by selecting the Transformation Steel option on the Materials tab or the Trans. Steel button on the Beam tab. Note, when you select the Transform Rebars option, you can input an area of mild steel to be used in the calculation of transformed properties in addition to the area of strands.

If you select the option to calculate transformed section properties, Precast/Prestressed Girder will consider the area of steel to calculate the section properties, multiplied by the term (n-1) where "n" is the modulus of elasticity of steel divided by the modulus of elasticity of concrete at 28 days and "1" accounts for the hole in the concrete caused by the presence of steel. If you do not choose this option, the section properties are calculated using the gross section properties assuming there is no steel present.

When using transformed section properties, most beam designs require fewer strands. For example, if you run Tutorial 1 in the user manual with transformed section properties, the automatically generated strand pattern will contain only 34 strands, as compared to 38 strands when not using transformed section properties (span1/beam 2).