Comparison of Approximate Linear Methods for Concrete Creep

The approximate methods for prediction of structural effects of creep, such as the effective modulus (EMM), age-adjusted effective modulus (AEMM), rate of creep (RCM), rate of flow (RFM), and Levi's and Arutyunian's methods are all linear and satisfy the principle of superposition. Predictions of the approximate methods are compared with the exact numerical solutions based on the principle of superposition and given (undistorted) realistic unit creep curves. It is found that AEMM is in general superior to all other methods and along with EMM is also the simplest one. RFM (with effective modulus treatment of delayed elastic strain) appears as second best and should be resorted to when the table of aging coefficient required by AEMM is unavailable.