不同应变速率下混凝土劈拉性能试验研究

EXPERIMENTAL RESEARCH ON SPLITTING TENSILE PERFORMANCE OF CONCRETE UNDER DIFFERENT STRAIN RATE

对尺寸为φ150 mm×150 mm圆柱体混凝土试件在不同加载方式(轴向加载、径向加载)、不同应变速率(10^(-5),10^(-4),10^(-3),10^(-2)s^(-1))下进行劈拉试验。分析混凝土力学性能随应变速率变化的规律,结果表明:混凝土劈拉强度随着应变速率的增大而增大;径向加载时,混凝土的劈拉强度比轴向加载时混凝土的劈拉强度高;轴向加载时混凝土的劈拉强度对应变速率更为敏感,混凝土的动态劈拉强度与应变速率的对数呈近似线性关系;混凝土吸能能力随着应变速率的增大而增大;轴向加载时,混凝土的吸能能力对应变率更敏感;与理论对比分析,径向加载曲线拟合精度更高,更符合实际受力情况;通过试验验证,发现改进的Mazars模型能很好地描述混凝土劈拉本构关系。

Splitting tensile tests for concrete of size Ф150 mm× 150 mm were carried out under different strain rate （10^-5 ,10^-4,10^-3,10^-2 s^-1）and different conditions （axial load, radial load）. The mechanical properties of concrete changes with strain rate were analysed, the results showed that the splitting tensile strength of concrete increased with strain rate, and the radial splitting tensile strength of concrete was higher than that of axial strength; the splitting tensile strength of axial load was more sensitive to strain rate; the dynamic splitting tensile strength of concrete and the logarithm of strain rate showed approximately linear relation; the energy absorption capability of concrete increased with strain rate; the energy absorption capacity of concrete was more sensitive to strain rate under axial load. Compared with the related theories, the accuracy of radial load curve fitting was high and more in line with the actual stress state. Through the test, the improved Mazars model could describe the split constitutive relation of concrete very well.