The part of this curvature caused by creep can be separated:

Introducing the following parameters:

ic = radius of gyration of concrete area is = radius of gyration of reinforcement area curvatures can be expressed in the following way:

Under design load and total bending moment Md the total curvature will be, including creep due to a long-term bending moment Ml:

The same curvature expressed with the effective creep ratio would be, see expression (4-7):

EJC i + (( + -ef )ß Combining expressions (4-9) and (4-10), after simplification:

1 + {1 + p)vef 1 + p Md ^ 1 + (1 + p) 1 + P From this the effective creep ratio can be solved:

2 Subscripts L and D are used in this chapter for simplicity; they correspond to Eqp and Ed in 5.8.4.

3 Non-linear effect will be dealt with later, see clause 4.3.

4 Theoretically this is not fully correct, since concrete stresses will decrease and reinforcement stresses increase with time. However, it is a reasonable approximation in most cases.


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