Consideration of non-linear creep: the value of k2
Eurocode 2 part 1-1: Design of concrete structures 7.2 (3)
If the stress in the concrete under the quasi-permanent loads is less than k2fck, linear creep may be assumed. If the stress in concrete exceeds k2fck, non-linear creep should be considered (cf. § 3.1.4).
The recommended value of k2 for the calculation of the limit of concrete compressive stress is 0,45.