Creep of Concrete: A Consistent Engineering Approach

Test procedures and two forms of the linear creep laws of concrete are compared. The first form consists of a product of age and duration functions while in the second, the reversible and irreversible creep are treated separately. It is concluded that the latter method is preferable for the practical specification of creep and that this should be based on tests that include measurement of creep recovery following unloading since the best prediction for practical stress histories is achieved in this way. It is shown that if this approach is taken, creep at different temperatures and humidities can be treated from a common standpoint. The irreversible component is affected by temperature and humidity variation whereas the other two components are affected to a negligible extent. Based on a simplified form of the creep equation, in which the reversible creep is combined with the elastic strain, various problems are analyzed using viscoelastic theory.