Validation of international concrete creep prediction models by application to South African concretes

Creep deformation of concrete is often responsible for excessive deflections at service loads which can compromise the performance of a structure. National design codes therefore provide prediction models for the estimation of creep deformation. These models are empirical-based. This paper assesses the accuracy of six international code type models, when compared with the actual strains measured on a range of South African concretes under laboratory control conditions. The models considered are those contained in AS 3600 (2001), AS 3600 (2009), Eurocode EC 2 (2004), GL (2000), GL (2004) and GZ (1993). The results indicate that for the range of concretes tested, the GL (2000) model yielded the most accurate predictions, giving the lowest overall coefficient of variation (ωall) of 31,9%. The least accurate method was the AS 3600 (2009) which yielded an overall coefficient of variation (ωall) of 74,7%. This paper also recommends a new approach to assessing the accuracy of creep models.