混凝土受压性能的非均质细观数值模拟

将混凝土看作是由骨料、砂浆及它们之间的界面组成的三相复合材料,在细观层次上建立了非均质混凝土棱柱体试件的随机骨料模型,分别赋予细观单元弹脆性损伤本构关系或弹塑性本构关系,研究了采用不同本构关系的混凝土棱柱体试件在单轴压缩荷载作用下的细观损伤演化过程,获得了相应的混凝土单轴受压宏观应力-应变曲线,并将计算结果与试验结果做了比较.结果表明:混凝土试件的破坏是由于细观损伤的积累导致的;非均质模型计算所得的宏观应力-应变曲线上升段与试验结果吻合相对较好,弹塑性本构模型计算所得的曲线下降段比弹脆性模型更接近于试验曲线.

Mesoscopic Numerical Simulation on the Compressive Behaviour of Heterogeneous Concrete

In order to study the compressive behavior of concrete under uniaxial compressive load at mesoscopic level, a random aggregate model at mesoscopic level in Monte Carlo method was developed, considering the concrete as a three-phase composite material of aggregate, mortar and the interface between them. Mesoscopic numerical models for heterogeneous concrete were established, in which the elastic brittle constitutive relationship for aggregate and the interface elements, and elasto-plastic constitutive relationship for motar elements were adopted. The results have shown that the failure of concrete is mostly due to the accumulation of damage at mesoscopic level, and the predicted macro-stress strain relationships of concrete under uniaxial compression agree better with the test results when the heterogeneity of concrete is considered and the elasto-plastic relationship for mortar element is used.