【摘要】 将混凝土视为砂浆、骨料及过渡界面组成的三相复合材料,采用随机骨料模型从细观角度对混凝土轴压破坏过程及抗压强度尺寸效应进行数值分析。该模型中考虑了混凝土级配以及骨料分布的影响,通过赋予各相材料塑性损伤本构关系并引入初始缺陷来模拟混凝土破坏过程中裂缝的产生与扩展。通过与试验数据进行对比,认为所建立随机骨料细观模型能够较好地反映混凝土抗压强度尺寸效应规律。分析结果表明:初始缺陷大小对混凝土抗压强度尺寸效应影响显著,而混凝土强度等级与缺陷位置对尺寸效应影响较小。通过对混凝土轴压破坏机理进行分析,发现基于能量释放的尺寸效应模型能够较好地解释混凝土的破坏过程和预测模拟结果。更多还原

【Abstract】 Concrete is composed of cement,aggregates,and the interface. A three-phase mesoscale model is adopted to analyze the size effect of concrete compressive strength and failure mechanism. The random distribution of coarse aggregate is considered during the establishment of the model. By assigning each phase its own damaged plasticity property and introducing initial defects,this mesoscale model can successfully simulate the propagation of the blunt crack band. Comparing with experimental data,the simulation makes a well prediction in the size effect of concrete compressive strength. The research results show that the size of the defect exerts a significant influence on the ultimate compressive capacity of concrete columns,while the strength grade of concrete and the location of defect present weak impacts. Finally,it is found through the analysis of failure mechanism that the size effect theory based on energy dissipation can perfectly account for the failure process and the simulation results.更多还原