Page 413 - Forensic Structural Engineering Handbook
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12.4 MATERIAL-SPECIFIC FORENSIC ANALYSES
800
w/cm = 0.7
600
Shrinkage strain, millionths in. per in. 400 w/cm = 0.4
200
“w/cm” is water-to-
cementitious-
materials ratio
0
0 28 90 180 days 1 year 2 years
Time of drying
FIGURE 12.3 Representative drying shrinkage for concrete. (Courtesy of CTLGroup.)
In Fig. 12.4, the upper curve shows the combined amounts of instantaneous strain,
shrinkage strain, and creep of concrete under compressive load. As can be seen, creep
strains can be significantly greater than either shrinkage strains or instantaneous strains. All
three contribute to deflections. If creep and shrinkage strains are allowed to be too high,
1500
Total Creep
Compressive strain, millionths 1000 Drying shrinkage
500
Instantaneous deformation
0
0 500 1000 1500
Age, days
FIGURE 12.4 Representative strains in a reinforced concrete column under compressive loading.
(Courtesy of CTLGroup.)
