Tensile stress limitation in the reinforcement at SLS to avoid unacceptable cracking or deformation: the values of k3, k4 and k5
Eurocode 2 part 1-1: Design of concrete structures 7.2 (5)
For the appearance unacceptable cracking or deformation may be assumed to be avoided if, under thecharacteristic combination of loads, the tensile stress in the reinforcement does not exceed k3fyk. Where the stress is caused by an imposed deformation, the tensile stress should not exceed k4fyk. The mean value of the stress in prestressing tendons should not exceed k5fpk.
The recommended values of k3, k4 and k5 for the tensile stress limitation in the reinforcement are 0,8, 1 and 0,75 respectively.