不同强度混凝土高温下动态劈拉性能研究

采用大直径分离式霍普金森压杆(SHPB)装置和加温装置，在不同温度(20 ℃、200 ℃和400 ℃)下对3种不同强度(C20、C45和C70)混凝土材料开展不同应力率的动态劈裂拉伸实验，得到了温度和应力率耦合作用下混凝土材料的动态劈裂强度及相应的破坏形态。实验结果表明，混凝土材料的动态劈裂强度随应力率的增加而增加，且应力率相近时，其动态劈裂强度随温度的增加而明显降低。在此基础上给出了描述混凝土材料在不同温度下的动态劈裂强度与应力率关系的表达式，并确定了相关材料参数。通过对不同应力率和温度耦合作用下混凝土材料的动态劈裂强度进行横向对比，发现混凝土材料动态劈裂强度的温度敏感性随应力率的增加逐渐减小，并且随着混凝土材料强度的增加其温度敏感性也逐渐变小，但是其动态劈裂强度的应力率敏感性却随着温度的升高逐渐增大。

RESEARCH ON DYNAMIC SPLITTING-TENSILE PROPERTIES OF CONCRETES WITH DIFFERENT STRENGTH AT HIGH TEMPERATURE

The large-diameter split Hopkinson pressure bar(SHPB) device and heating device were used to perform dynamic splitting-tensile experiments on three concrete materials with different strengths(C20, C45 and C70) at different temperatures(20 ℃, 200 ℃ and 400 ℃). The dynamic splitting strengths and corresponding failure patterns of concrete materials under the coupling effect of temperature and stress rate are obtained. The results show that the dynamic splitting strength of concrete material increases with the stress rate, but when the stress rates are similar, the dynamic splitting strength decreases significantly as the temperature increases. On this basis, the equations describing the relationship between the dynamic splitting strength and the stress rate of concrete materials at different temperatures are given, and the related material parameters are determined.Comparing the dynamic splitting strength of concrete materials under the coupling effect of stress rate and temperature, it is found that the temperature sensitivity of dynamic splitting strength decreases as the stress rate increases, and gradually decreases with the concrete material strength, but the stress rate sensitivity of dynamic splitting strength increases with the temperature.