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轴向拉伸试验是确定混凝土拉伸断裂特性最直接的方法。利用中国水利水电科学研究院大型动态材料试验机开展了全级配混凝土大试件的动态轴拉试验研究。在试件与试验机之间设置铰接座组件以消除拉伸过程中附加弯矩的产生,并采取适当措施降低拉伸试验中偏心的影响。将20个全级配混凝土大试件、23个湿筛混凝土小试件按浇筑日期分为3组进行试验。结果表明,混凝土轴拉强度的骨料效应和尺寸效应十分显著,静态轴拉强度较动态轴拉强度受其影响更大;冲击荷载作用下,骨料破坏比例增加;轴拉强度与极限拉伸值的率敏感性显著;轴拉强度越低,其率敏感性越高;而抗拉弹性模量的率敏感性较低。
Axial tensile test is the most direct way to determine the tensile properties of concrete. Using the large dynamic material testing machine of China Water Conservancy and Hydropower Research Institute, the dynamic axial tension test of full grade concrete with large test pieces is carried out. Between the test piece and the testing machine, a hinge seat assembly is provided to eliminate the additional bending moment during the drawing process and take appropriate measures to reduce the influence of eccentricity in the tensile test. 20 full-scale concrete with large test pieces, 23 small pieces of wet-sieving concrete test pouring date is divided into 3 groups for testing. The results show that the aggregate effect and the size effect of the axial tensile strength of concrete are very significant. The static tensile strength is more affected by the tensile strength of the dynamic shaft. Under the impact load, the aggregate destruction ratio increases. The axial tensile strength and ultimate tensile strength The rate sensitivity is significant; the lower the axial tensile strength, the higher the rate sensitivity; and the lower the rate sensitivity of the tensile elastic modulus.