Time dependent losses of prestress due to creep, shrinkage and relaxation, ΔPc+s+r
Eurocode 2 part 1-1: Design of concrete structures 5.10.6 (2)
A simplified method to evaluate time dependent losses at location x under the permanent loads is given by:
- is the absolute value of the variation of stress in the tendons due to creep, shrinkage and relaxation at location x, at time t
- is the estimated shrinkage strain, in absolute value
- is the modulus of elasticity for the prestressing steel, see § 3.3.6 (2) and § 3.3.6 (3)
- is the modulus of elasticity for the concrete
- is the absolute value of the variation of stress in the tendons at location x, at time t, due to the relaxation of the prestressing steel. It is determined for a stress of σp = σp(G + Pm0 + ψ2Q) which is the initial stress in the tendons due to initial prestress and quasi-permanent actions
- is the creep coefficient at a time t and load application at time t0
- is the stress in the concrete adjacent to the tendons, due to self-weight and initial prestress and other quasi-permanent actions where relevant
- is the area of all the prestressing tendons at the location x
- is the area of the concrete section
- is the second moment of area of the concrete section
- is the distance between the centre of gravity of the concrete section and the tendons.
Compressive stresses and the corresponding strains should be used with a positive sign.
This application calculates the time dependent losses ΔPc+s+r from your inputs.