This paper presents a mesoscopic discrete modeling approach for studying compression and fracture behavior of concrete. A modified piecewise linear sieve curve was proposed to generate irregularly shaped aggregates following specific particle size distributions, and then a random particle model and the parallel bond model were implemented within a 3D framework of discrete element model (DEM). To characterize the interface transition zone (ITZ) which is generally the weak region in concrete, a reduction factor was employed to adjust the strength and consider the effect of ITZ on the mechanical response of concrete. The numerical modeling was calibrated and validated by comparing simulation results with experimental data from compression, splitting tensile, and dog-bone tests. The results demonstrate that the random aggregate model provides accurate representations of the concrete mesostructure, and the discrete model can effectively capture the effects of aggregate size distribution and ITZ on mechanical properties and crack propagation of concrete.

本文提出了一种用于研究混凝土压缩和断裂行为的细观离散建模方法。提出了一种改进的分段线性筛曲线来生成遵循特定粒度分布的不规则形状聚集体，然后在离散元模型 (DEM) 的 3D 框架内实现随机颗粒模型和平行键模型。为了表征界面过渡区（ITZ）（通常是混凝土中的薄弱区域），采用折减系数来调整强度并考虑ITZ对混凝土力学响应的影响。通过将模拟结果与压缩、劈裂拉伸和狗骨测试的实验数据进行比较，对数值模型进行了校准和验证。结果表明，随机骨料模型可以准确地表示混凝土细观结构，离散模型可以有效捕捉骨料尺寸分布和ITZ对混凝土力学性能