Elastic Shortening
Loss of prestress due to elastic shortening is a consequence of elastic shortening of a girder after release. When transformed section properties are used, the loss of prestress due to elastic shortening does not have to be evaluated explicitly since the equations for evaluation of stress already includes the effect of elastic shortening. This is because the area and moment of inertia of the cross-section includes the transformed steel, as verified in Reference 6; Design of Prestressed Concrete Structures, Chapter 5 p. 126-132.
When using transformed steel, Precast/Prestressed Girder shows ES as zero in the output. This does not mean that there is no elastic shortening. It simply means that ES is included as part of the stress equations and is not calculated separately. When using gross section properties, Precast/Prestressed Girder follows the traditional past practice of not explicitly considering the elastic gains, and therefore may come up with conservative (higher) loss values than the newer methods as per the latest Interims
When using transformed steel, Precast/Prestressed Girder computes the Elastic shortening loss as well as gain due to applied loads in the loss computations, but does not use these values in the stress computations, when transformed section properties are used. However, when using gross/non-transformed section properties, Precast/Prestressed Girder not only computes these elastic losses and gains, but also considers them in the stress computations.