基于统计损伤理论的混凝土双轴拉-压本构模型研究

Constitutive Model for Concrete Under Biaxial Tension-Compression Stresses Based on Statistical Damage Theory

基于细观统计损伤理论及宏观试验现象,本文建立了混凝土双轴拉-压细观统计损伤本构模型.该模型考虑断裂、屈服两种细观拉损伤模式,损伤演化过程由主方向的拉、压应变驱动.将单轴拉伸、单轴压缩作为两种最基本的宏观破坏形式,复杂应力状态下的损伤破坏过程理解为单轴拉伸、压缩损伤演化过程的某种组合形式.引入等效传递拉损伤应变和损伤影响参数,建立宏观拉、压破坏模式对应细观损伤机制之间的等效关系.通过与试验结果比较,表明该模型能够很好地模拟双轴拉-压加载情况下材料均匀损伤阶段的力学行为.对双轴拉-压比例加载路径下应力-应变曲线进行预测,提取出双轴拉压强度包络线,从双轴强度、变形特性、破坏形态等角度对材料的双轴拉-压损伤机制进行探讨.

The statistical damage constitutive model for concrete under biaxial tensile and compressive stresses was proposed,based on the statistical damage theory and the experimental phenomena.It considered two meso-scale damage modes,rupture and yield. The evolution process of damage was driven by the principal tensile and compressive strains. The damage evolution process of concrete under complex stress state was considered as the combination of uniaxial tension and uniaxial compression,which were regarded as the two most fundamental failure forms. The equivalent relations of micromechanical damage mechanisms corresponding to the macroscopic tensile and compressive failure modes were established,by introducing the concepts of equivalent transfer tensile damage strain and the damage influence parameter. The results show that it can accurately predict the constitutive behavior in the uniform damage phase for concrete under biaxial tension and compression. The damage mechanism was discussed from the view points of biaxial strength,deformation properties and the failure form.