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.