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Effects of prestressing at SLS and limit state of fatigue: the values of rsup and rinf

Eurocode 2 part 1-1: Design of concrete structures   5.10.9 (1)P

For serviceability and fatigue calculations allowance shall be made for possible variations in prestress. Two characteristic values of the prestressing force at the serviceability limit state are estimated from:

Pk,sup = rsup Pm,t(x) (5.47)
Pk,inf = rinf Pm,t(x) (5.48)


is the upper characteristic value
is the lower characteristic value.


The recommended values of rsup and rinf for the effects of prestressing at SLS and limit state of fatigue are:

- for pre-tensioning or unbonded tendons: rsup = 1,05 and rinf = 0,95
- for post-tensioning with bonded tendons: rsup = 1,10 and rinf = 0,90
- when appropriate measures (e.g. direct measurements of pretensioning) are taken: rsup = rinf = 1,0.

National choice