Influence of concrete strength and aggregate size on the size effect of shear capacity of RC beam-column joints under monotonic loading: Mesoscale numerical tests

Abstract

In this research, the influence of width on mechanical performance of joints is studied by numerical tests based on 2D mesoscale models. Meanwhile, the effects of concrete strength and aggregate particle size on size effect of joints are analyzed. Firstly, the proposed 2D mesoscale model, which is reflective of the heterogeneity of concrete and damage development within joints, is validated based on existing experimental results. Secondly, based on the proposed 2D mesoscale model, a range of numerical tests about size effect are conducted. It turns out that, the size effect of shear capacity becomes more remarkable with the increasing concrete strength and the decreasing aggregate size. Thirdly, the size effect of joints is discussed based on different SELs (size effect laws). The Type-II SEL proposed by Bažant (1984) is initially adopted to evaluate the size effect of joints. Although it can give generally adequate trends on size effect, the nominal shear strength of joints considering the effect of concrete strength and aggregate size cannot be calculated quantitatively. Therefore, the authors present a new SEL that considers concrete strength and aggregate size, which is able to give concise shear capacity of joints.