混凝土一种假三轴塑性本构模型

A Plastic Constitutive Model for ConcreteUnder General Triaxial Quasistatics Loading Condition

在试验中发现:混凝土在很小的压力下就有塑性变形,混凝土的应力状态达到峰值前甚至峰值后不一定会有扩容.考虑了这两个试验现象,在构造的模型中假定混凝土初始屈服强度为零,从而模型算出的单调加载条件下的应力_应变曲线具有和试验相符合的光滑、连续的特征.提出了判断材料的应力状态到达峰值前是否出现扩容的方法,使模型能对扩容和不出现扩容两种试验现象进行模拟.模型与沿4组假三轴压缩比例加载应力路径对混凝土加载的试验结果进行了对比,模型对实验中混凝土的峰前段应力_应变关系能进行合理模拟,对峰值后可模拟小段范围内的应力_应变关系及其趋势.

Experiment shows that plastic deformation occurs in concrete under low compressive pressure; compressive failure is feathered with dilation before peak point of stress, but not all failure is accompanied by dilation. In this model the initial yield stress is zero, so the stress-strain curve is feathered with smoothness and continuity; a method of discerning if dilation occurs before peak point of stress is proposed and dilation can be modeled. The model predictions are compared with experiment of different proportional loading cubic concrete specimens in compression. These experiments include 4 groups of general triaxial quasistatics loading condition.