Why is the pre-stress elastic deformation loss sometimes positive?
Relief in Elastic Deformation of member is reflected as positive
Prestress elastic deformation losses includes elastic shortening losses,
which are caused by subsequent loadings (self weight, live loads, creep, shrinkage, etc.)
after the prestressing force is applied.
With the passage of time, tendons undergo relaxation which results in reduction of prestress forces and
relief of deformation of prestressed member which underwent shortening under prestress.
This relief in elastic deformation of member is reflected as a positive elastic deformation loss as shown above in the tendon loss results table.
If the prestress load/stress application is done in subsequent stages or as per the actual stressing sequence,
then the elastic deformation loss would be negative as sequential stressing results in axial deformation and prestress loss.