混凝土细观数值试验的随机损伤本构模型

Stochastic Damage Constitutive Model of Mesoscopic Numerical Test of Concrete

混凝土在细观尺度下是由粗骨料、砂浆和界面过渡区(ITZ)组成的三相复合材料。目前考虑细观尺度上这三相之间力学性能的不同,已经进行了大量的细观数值试验研究。然而混凝土为典型的多尺度材料,在细观尺度下混凝土各相自身也是非均质的。鉴于此,提出了细观尺度下代表性体积单元(RVE)的随机损伤本构模型,并编制了相应的有限元程序。利用编制的程序,进行了随机骨料模型单轴拉伸和压缩数值试验;并进行了双骨料试件单轴拉伸数值试验。结果表明,该模型虽然结构简单,但能较好地反映混凝土的主要宏观力学行为和细观损伤的产生和演化发展。最后,通过参数敏感性分析,阐明了不同模型参数对混凝土宏观力学特性的影响。该模型可为混凝土细观数值试验研究提供支撑。

Concrete is a three-phase composite material composed of coarse aggregate,mortar matrix and interface transition zone( ITZ) at mesoscale. At present,a large number of mesoscopic numerical experiments have been carried out in consideration of different mechanical properties among these three phases. However,concrete is a typical multi-scale material,and each phase is heterogeneous at mesoscale. In view of this,a stochastic damage model of the representative volume element( RVE) at mesoscale was proposed,and the corresponding finite element program is developed. Then the uniaxial tensile and compressive numerical test of the random aggregate model,and the uniaxial tensile test of the double-aggregate model are conducted to validated the model. The results show that despite the simplicity of the model,it can reflect the main macro-mechanical behavior of concrete and the initiation and propagation of mesoscopic damage. Finally,through the parametric study,the effect of different model parameters on the macro-mechanical properties of concrete is illustrated. In a word,the model can provide support for mesoscopic numerical test of concrete.