Size effect modelling for dynamic biaxial compressive strength of concrete: Influence of lateral stress ratio and strain rate

Abstract

Concrete structures are often in complex stress state for a long time in practical engineering. This study presents a numerical investigation on the influence of strain rate and lateral stress ratio on the dynamic biaxial compressive failure and the corresponding size effect of concrete. A 3D meso-scale modelling approach considering concrete heterogeneity was established. The mechanical responses of cubic concrete specimens having different sizes under dynamic biaxial compressive conditions with different strain rates and lateral stress ratios were simulated. The simulation results indicate that under the same lateral stress ratio, the size effect on dynamic biaxial compressive strength is gradually weakened with the increasing strain rate. Under the same strain rate, the size effect is weakened first and then strengthened with the increasing lateral stress ratio. At the same time, the increasing strain rate would weaken the influence of the lateral stress ratio on the size effect. In addition, the strength criteria for dynamic biaxial compressive strength of concrete under medium and low strain rates was proposed and verified. Finally, a semi-empirical and semi-theoretical size effect formula considering the quantitative influence of strain rate and lateral stress ratio on the size effect was established.