Summary
A function expressing creep process in concrete was searched. Unlike most investigations carried out under constant stress, the report concerns the creep of concrete elements subjected to prestressing force, which decreased constantly due to interdependence of strains in concrete and in reinforcement.
The measurements show that the creep rate decreases much slower than is usually anticipated and after 7 years the phenomenon can still be observed. It is found that the simple power function y=t 0.11 is adequate for dry stored test pieces, regard-to failure in conditions of creep at decreasing stress.
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Abbreviations
- C:
-
ɛ f /σ creep measure
- C1 :
-
ɛ f /σ0
- C2 :
-
ɛ f /σ(t)
- t :
-
time
- y :
-
creep function for whichy(∞)=1
- Y :
-
creep function for whichy(t 0)=1
- α t :
-
coefficient of thermal expansion
- ɛ:
-
strain
- ɛ e :
-
instantaneous strain
- ɛ f :
-
creep strain
- ɛ r :
-
shrinkage strain
- ϕ:
-
ɛ f /ɛ e creep coefficient
- σ:
-
stress
- σ0 :
-
initial stress
- σ r :
-
concrete strength at prestressing
- τ:
-
age of material at loading
- η:
-
σ0/σ r stress level
References
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Kajfasz, S., Szulc, J. Approximation of experimental data by a creep function. Mat. Constr. 3, 381–394 (1970). https://doi.org/10.1007/BF02478762
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DOI: https://doi.org/10.1007/BF02478762