A Constitutive Model for Non-linear Basic Creep of Plain Concrete

Abstract

It is well known that plain concrete suffers from creep under sustained loads. Although various constitutive models have been proposed in the last years, these approaches are often restricted to linear creep of concrete at low load levels, face difficulties regarding multiaxial stress and deformation states, or involve a large number of parameters. The current contribution aims at closing this gap and presents a new robust modelling approach for the non-linear basic creep of plain concrete. Coupled non-linear evolution equations are formulated with respect to the creep strain and a backstress variable, which allows for the consideration of hardening effects. Both uniaxial and multiaxial stress conditions are taken into account, and the Drucker-Prager equivalent stress is utilized. Material parameters are determined based on compressive and tensile creep tests. Furthermore, the model is verified against an additional set of creep tests, which demonstrates that the proposed concept provides an accurate prediction for basic creep of concrete. Thereby, the concept is applicable for loads up to 70% of the short-term strength, while requiring a relatively low number of material parameters.