Article 1 of the "Code for Design of Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts" (JTG 3362-2018) states:
For prestressed concrete components, the tension control stress value σcon of prestressed steel bars (for post-tensioned components, it is the anchor stress in the beam body) should comply with the following regulations:
1. The tension control stress value of steel wire and steel hinge wire σcon≤0.75fpk;
2. The tension control stress value of precision rolled rebar σcon≤0.90fpk. (fpk refers to the standard value of tensile strength of prestressed steel bars)
In addition, when calculating the normal serviceability limit state of prestressed concrete components, the loss of prestress caused by the following factors should be considered:
Friction between prestressed steel bars and pipe wall σl1
Anchor deformation, steel retraction and joint compression σl2
Temperature difference between prestressed steel bars and base σl3
Elastic compression of concrete σl4
Stress relaxation of prestressed steel bars σl5
Shrinkage and creep of concrete σl6
In addition, other prestress losses caused by factors such as friction between the prestressed steel bars and the anchors and elastic deformation of the pedestal should be considered.
When the component is over-tensioned or the opening of the anchor ring is lost, the maximum controlled stress in the steel bar (the value displayed on the jack oil pump) should not exceed 0.8fpk for steel wires and steel hinges; it should not exceed 0.95fpk for precision-rolled threaded steel bars. 

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