Coupled hygro-mechanical meso-scale analysis of long-term creep and shrinkage of concrete cylinder: Fid-Bau Portal

Coupled hygro-mechanical meso-scale analysis of long-term creep and shrinkage of concrete cylinder

Ožbolt, Joško / Gambarelli, Serena / Zadran, Sekandar

Highlights • The interaction between load-induced damage of concrete and its non-elastic time deformations (drying shrinkage and basic creep of mortar) is studied using a 3D hygro-mechanical meso-scale FE model for concrete. • The employed two-phase meso-scale model is able to realistically reproduce the long time experimental tests for shrinkage, basic creep and drying creep. • The strong interaction between drying shrinkage and load-induced damage of mortar is observed, which seems to be mainly responsible for drying creep and reduction of sustained strength of concrete, especially for tension. • It is observed that there is no strong interaction between load-induced damage and basic creep. • Basic creep has positive effect on drying creep of concrete in compression because it partly compensates load-induced damage due to drying shrinkage of cement paste.

Abstract In the present study the interaction between the load-induced damage of concrete and its non-elastic time deformations, drying shrinkage and basic creep of mortar, is numerically investigated through a 3D meso-scale finite element (FE) simulation. The transient numerical analysis is performed by employing two-phase meso-scale FE discretization of concrete (aggregate and mortar). The constitutive law for mortar is based on the hygro-mechanical model, which couples the Fickian moisture transport and the microplane-based mechanical model. In the model the total strain is decomposed into mechanical, drying shrinkage and basic creep strains. After calibration and verification of the model a parametric study is carried out for the sustained tensile and compressive load. It is shown that the meso-scale model for concrete is able to replicate the long-term experimental tests for drying creep based only on the interaction between damage, drying shrinkage and basic creep, without the need for any additional viscos kind of mortar strains due to drying. The parametric study showed that there is a strong interaction between drying shrinkage, the load-induced damage of mortar and heterogeneity of concrete. This mainly contributes to drying creep of concrete and leads to the reduction of uniaxial compressive strength to approximately 80% of short-term strength. For tensile load the interaction is even stronger and causes the reduction of short term tensile strength to approximately 40%. The study also indicates that there is no strong interaction between the load-induced damage and basic creep of mortar.