Multi-layer visco-elastic creep model for time-dependent analysis of concrete structures

Abstract

Time-dependent analysis of shrinkage and creep effects on concrete structures is crucial for the assessment of shrinkage cracking problem as well as for the evaluation of mitigation measures. For general structures, the time-dependent analyses are most suitably conducted using the finite element method. In accordance with the conventional concrete creep models (including the prevalent codified formulations), when the stresses in concrete vary with time, the corresponding creep strains at any time have to be determined as a summation of individual creep responses due to stress increments in preceding time intervals. However, such summation process entails the memorisation of stress histories for all finite elements, thus leading to prohibitive computer storage requirements for large analysis problems. In this paper, a multi-layer visco-elastic creep model is developed for concrete by combining rheological elements in an optimal configuration. The model successfully circumvents the need of memorising the stress histories of concrete, thereby greatly facilitates the computer analyses of timedependent effects on concrete structures. To demonstrate the general applicability of the proposed model, numerical examples on restrained concrete prism and concrete podium structure are presented. © 2007 Civil-Comp Press.