单轴荷载作用下混凝土强度代表体尺寸定量研究
Quantitative Study on the Representative Volume Element Size of Concrete Strength under Uniaxial Loading

为从细观层次研究混凝土宏观力学性能，提出了混凝土强度代表体定义，建立了基于统计特征的混凝土强度代表体尺寸确定方法。采用三维随机缺陷界面弹簧元模型，给出了确定单轴加载下的混凝土强度代表体尺寸的数值方法。分析了不同数值样本取值对混凝土单轴受拉及单轴抗压强度值离散性的影响规律，以及尺寸试件变化对混凝土拉伸及受压强度仿真结果稳定性的影响规律。研究结果表明：在单轴拉伸荷载和单轴压缩荷载作用下，混凝土强度代表体尺寸分别为5.0倍和6.5倍最大骨料粒径；与基于细观结构统计特征确定的混凝土几何代表体尺寸的相比，证明了本文所提方法的合理性。
Based on meso-numerical simulation technology, a new method was developed for the determination of the RVE (representative volume element) (RVE) of concrete. The uniaxial tensile and compressive strength of concrete specimens with various RVE size were calculated by means of the interfacial spring element model. Then the RVE size was determined quantitatively by analyzing the discreteness of concrete strength and the increase trend of concrete strength. Results showed that the RVE size for concrete uniaxial tensile and compressive strength were 5 times and 6.5 times of maximum aggregate diameter of concrete respectively, which were close to the RVE sizes for concrete micro-structure. This study can enrich the numerical methods for strength analysis of concrete and lay a foundation for multi-scale analysis of concrete.