# Limitation of concrete stress during tensioning in steps: the values of `k`_{4} and `k`_{5}

_{4}

_{5}

## Eurocode 2 part 1-1: Design of concrete structures 5.10.2.2 (4)

If prestress in an individual tendon is applied in steps, the required concrete strength may be reduced. The minimum strength `f _{cm}`

`(t)`at the time

`t`should be

`k`[%] of the required concrete strength for full prestressing given in the European Technical Approval. Between the minimum strength and the required concrete strength for full prestressing, the prestress may be interpolated between

_{4}`k`[%] and 100% of the full prestressing.

_{5}## Recommendation

The recommended value for `k _{4}` is 50% and that for

`k`is 30% for defining the limitation of concrete stress.

_{5}