The approximate value of shrinkage strain for design of posttensioning member is
Where ‘t’ = age of concrete at transfer in daysConcept:
Shrinkage strain:
As per IS 1343:1980, cl. 5.2.4.
For pretensioning = 0.0003
For posttensioning = \(\frac{0.0002}{\log(t+2) }\)
Where, t  age of concrete at transfer in days.
Important Points
\(ϵ_{cs}= ϵ_{cd}+ϵ_{ca}\)
Here,
ϵ_{cd}  Drying shrinkage strain
ϵ_{ca}  Autogenous shrinkage strain.
Drying shrinkage strain  Autogenous Shrinkage strain 

