In Precast/Prestressed Girder, you can use transformed section properties for the beam design by selecting the Transform Steel option on the Materials tab or the Trans. Steel button on the Beam tabn. Note, when you check 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.

In the Pre-2005 Loss method, when not using the transformed section properties option, Precast/Prestressed Girder uses the gross section properties method which follows what has been industry practice for many years. This is because elastic gains are not included and the result may be a reduction of compression in the beam bottom at mid-span. When using the Pre-2005 loss method and transformed section properties, Precast/Prestressed Girder follows the traditionally used approach of not using the Elastic Shortening losses in computation of stresses (or losses).

However, when the Approximate method of computing time dependent losses, Precast/Prestressed Girder computes elastic losses and gains and applies them in the computation of stresses only to the cases where gross section properties are used and not for the cases where transformed section properties are used to compute stresses. This is in accordance with the recommendations in Art. C5.9.5.3 which states that the losses or gains due to elastic deformation at the time of transfer or load application should be added to the time-dependent losses to determine total losses. However, these elastic losses (or gains) must be taken equal to zero if transformed section properties are used in stress analysis.