混凝土应变软化与局部化的数值模拟

在细观层次上将混凝土看作是一种由粗骨料、砂浆和它们间的粘结带组成的三相复合材料，根据蒙特卡罗随机抽样原理，在计算机上随机生成了碎石骨料的混凝土随机骨料结构，建立了正交各向异性损伤本构方程，提出了适合细观有限元分析的强度与韧性综合破坏准则以及优先开裂原理，利用中模型和方法，数值模拟了混凝土单轴受拉试件的细观破坏过程，逼真地阐明了名的应变软化与局部化现象，说明了混凝土细观有限元分析是一种研究混凝土基本特性的行之有效的数值分析方法。

Numerical Simulation of Strain Softening and Localization for Concrete Materials

At the mesoscopic level, concrete materials are regarded as three phase composites consisting of coarse aggregate, mortar matrix and bond zone between the matrix and aggregate. Based on random sampling principle of Monte Carlo method, a random crushed aggregate structure is generated on computer to simulate real heterogeneous structure. An orthotropic damage constitutive equation is proposed based on equivalent strain concept. A failure criterion combining fracture toughness and strength is presented which is specifically suitable for finite element analysis of meso structure. The principle of orderly cracking in an iterative is presented to get true failure pattern and path. As an application, all failure processes are numerically simulated of uniaxial tension of a concrete speciment. The famous strain softening and localization are lifelikely explained and the micromechanisms of failure are successfully simulated.