高温高应变率下混凝土材料的损伤演化方程

采用?74 mm大口径分离式霍普金森压杆(SHPB)对不同温度(20、200、400℃)下的C45混凝土材料进行动态力学性能实验,得到了不同温度、不同应变率下混凝土材料的应力-应变曲线。实验结果表明:在20~400℃温度范围内,混凝土材料具有温度硬化和应变率硬化现象。基于上述实验数据给出了损伤变量关于塑性应变的关系式,并通过相关实验数据确定了不同温度、不同应变率下损伤演化方程的材料参数。将该损伤演化方程应用于混凝土材料的本构关系中,预测结果与实验数据具有较好的一致性,证明了所提出的高温、高应变率下混凝土材料损伤演化方程的合理性。

Damage Evolution Equation of Concrete Materials at High Temperatures and High Strain Rates

In this paper,the dynamic mechanical properties of C45 concrete materials at different temperatures(20,200,400℃)are carried out on split Hopkinson pressure bar(SHPB)equipment with a large diameter of 74 mm.The stress-strain curves of concrete materials at different temperatures and strain rates are obtained through experiments.As the expansion of microcracks inside concrete materials is inhibited by the increase of strain rate,the concrete specimens exhibit strain rate hardening effect.The experimental results show that the concrete material has temperature hardening and strain rate hardening in the temperature range of 20℃ to 400℃.Through the relevant theoretical derivation,the SHPB experimental data of concrete materials are transformed into the relationship between damage variables and plastic strain.Then the material parameters of the damage evolution equation at different temperatures and different strain rates are determined by relevant experimental data.Finally,the damage evolution equation of concrete materials at high temperatures and high strain rates are applied to the constitutive relation of concrete materials.The prediction results are in good agreement with the experimental data.