混凝土静动态单轴抗拉本构关系试验研究

An Investigation on Intrinsic Stress-Strain Relationship of Concrete Subjected to Static and Dynamic Uniaxial Tension

轴向拉伸试验是确定混凝土拉伸力学性能最直接的方法。利用MTS试验机和自行研制的夹具,在试件与试验机之间设置球铰组件以消除拉伸过程中附加弯矩的影响,并采取适当措施降低拉伸试验中偏心的影响,完成了应变率由10-6~10-3s-1 4个数量级范围内的混凝土静动态轴向拉伸试验。试验结果发现不同应变率下,混凝土轴向拉伸全过程曲线有着很好的相似性,峰值应力和弹性模量随着应变率的增加而增加,但极限拉伸应变基本不变。在纤维束模型的基础上,建立了考虑应变率效应影响的统计本构方程,其计算结果与试验值吻合较好。

Axial tensile test is the most direct way to determine the tensile mecnantcat proverties of concrete. This paper used MTS testing machine and developed fixture. Setting ball hinge components between specimens and testing machine to eliminate the influence of the additional bending moment in the process of drawing, and taking appropriate measures to reduce the effect of eccentricity in the tensile test. This paper completed the static and dynamic axial tensile test of concrete within the scope of strain rate from the 10-6 s-1 to 10-3s-1. Under different stain rate, concrete axial tensile process curve has a good similarity. Peak stress and the elastic modulus increases with the in- crease of strain rate, but the ultimate tensile strain basically remains unchanged. On the basis of the fiber bundle model, this paper established a statistical constitutive equation by considering the strain rate effect, the calculation result has good agreement with the test results.