## Sdr

Tir"e A Deformation

Figure 5.20. Illustration of load history and deformations

Tir"e A Deformation

Figure 5.20. Illustration of load history and deformations

The total deformation under long-term load can also be calculated directly using an equivalent E-modulus3 for the concrete, Ee = E</(1+y). This corresponds to line AC in figure 5.20.4 The total deformation under design load can be calculated in a similar way if an effective creep ratio 9ef is used, line AD in figure 5.20. The "effective equivalent concrete modulus" would then be Eef = Ec/(1+ 9ef) where yef is the effective creep ratio.

### 5.8.4.2 Effect of creep in cross sections

In the following, three examples are used to derive and illustrate the effective creep ratio ^ef. The examples deal with bending moment and curvature in the following cases, assuming linear elastic material behaviour:

a) uncracked unreinforced cross section (5.8.4.2.1)

b) uncracked reinforced section (5.8.4.2.2)

c) cracked reinforced section (5.8.4.2.3)

### 5.8.4.2.1 Uncracked unreinforced cross section

This is the simplest case for demonstrating the idea behind the effective creep ratio. The total curvature under a long-term bending moment Ml is (cf. line AC in figure 5.20):

The part caused by creep can be separated:

0 0