From: Effect of a Time Dependent Concrete Modulus of Elasticity on Prestress Losses in Bridge Girders
tfinal (years)
kc (Eq. 11)
Creep coefficient, ψ (Eq. 8)
ACI f′c(t), MPa (Eq. 13)
5
0.659
1.94
4,698
10
0.689
2.09
4,700
15
0.700
2.16
4,702
20
0.705
2.19
4,703
25
0.709
2.22
30
0.711
2.23
4,704
35
0.713
2.25
40
0.714
2.26
45
0.715
50
0.716
2.27
4,705