Prediction of Concrete Creep by Multi-Layer Visco-Elastic Model

Creep of concrete can aggravate deflections of flexural members, cause loss of prestress in prestressed members, and augment differential axial shortening in tall buildings. The structural effects of concrete creep can be assessed by conducting time-dependent analysis. For complicated structures, the analysis has to be resorted to the use of finite element method, where the creep strain at any time is determined as the cumulative creep responses to the stress increments in previous time steps. This process entails the memorisation of stress histories of all concrete finite elements, hence leading to prohibitive demand of computer memory for practical large-scale problems. To facilitate such time-dependent analysis, the multi-layer visco-elastic model, whereby rheological units are combined for optimal representation of concrete creep, is developed for predicting concrete creep. This model circumvents the need of memorising the stress histories of concrete, and it possesses great flexibility to fit with the creep prediction formulae in any design code