Increase of the stress from the effective prestress to the stress in the ULS Δσp,ULS
Eurocode 2 part 1-1: Design of concrete structures 5.10.8 (2)
For prestressed members with permanently unbonded tendons, it is generally necessary to take the deformation of the whole member into account when calculating the increase of the stress in the prestressing steel. If no detailed calculation is made, it may be assumed that the increase of the stress from the effective prestress to the stress in the ultimate limit state is Δσp,ULS.
The recommended value for the increase of stress Δσp,ULS is 100 MPa.