中文摘要：

采用离散单元法对混凝土材料和混凝土结构破坏机理进行分析。在细观尺度上将混凝土材料视为由粗骨料、水泥砂浆及界面过渡区三相组成,建立了混凝土材料的离散元模型;在宏观尺度上将混凝土视为均质材料建立了混凝土结构离散单元模型。计算分析结果表明：细观尺度上的二维离散单元模型可以用来很好地模拟混凝土材料的单轴受力破坏过程,但不能很好地模拟复合受力状态下的混凝土材料的破坏;宏观尺度上的离散单元模型可以很好地模拟钢筋混凝土构件的破坏过程,但模拟结果对单元的形状有较大的依赖性;宏观尺度上的离散单元模型可以很好地模拟结构的倒塌过程,但计算效率有待提高。

英文摘要：

The damage mechanisms of concrete materials and structures were analyzed by the discrete element method（DEM）. On mesoscopic level, a concrete material numerical model was developed based on the DEM considering the composition of concrete materials which were coarse aggregates, mortar and their interface. On macroscopic level, a concrete structural numerical model was proposed assuming that the concrete was homogeneous. The simulation results indicated that the failure processes of concrete materials under uniaxial loading conditions could be well predicted by using the two-dimensional mesoscopic numerical model, but the damage processes of concrete materials under combined loading conditions could not be calculated correctly. The failure processes of reinforced concrete members could be accurately simulated by the DEM-based model on macroscopic level, but the calculated results had a great dependency on the shape of the elements. The collapse processes of reinforced concrete structures could also be predicted well by using the macroscopic numerical model, but the computational efficiency of the model should be further improved.