基于Ottosen模型的混凝土多轴动态强度准则

由于混凝土材料的率敏感特性,不同应变率水平下混凝土结构的承载力、刚度具有不同的变化机理。在地震作用下,除了考虑混凝土结构承受的复杂应力之外,应变率也是分析混凝土动态强度变化规律不可忽略的因素,若依然使用单轴拉、压、剪强度理论对工程进行设计和计算,可能会对大型结构的建设和使用带来危险。基于Ottosen静态强度准则模型,结合大量不同强度等级混凝土多轴静、动强度试验结果,建立了一种考虑应变率效应和混凝土强度等级两个因素的混凝土多轴动态强度准则。分析表明该强度准则符合混凝土破坏曲面连续、光滑、外凸等要求,能较好地反映普通混凝土的多轴动态强度变化规律,而且只需要通过几个特征点就能得到,形式简单,便于实际工程应用。

Dynamic strength criterion of concrete based on Ottosen model under multi-axial stress

Due to the characteristic of the rate sensitive material, the changing mechanism of strength and stiffness of concrete structure under various strain rates are different. In addition to the complex stress state where concrete structure is subjected to dynamic loading such as earthquake, the effect of the strain rate is an important factor that can not be ignored. If projects are designed and calculated with strength theories of uniaxial tension, compression and shear, there will have great potential dangers in the construction and use of structure. Based on the Ottosen criterion model, in the present paper, by analysis of multiaxial static and dynamic strength test data of numerous concrete specimens, which are classified into different strength grades, a multiaxial dynamic strength criterion is reasonably established, in which both the strain rate effect and the strength of concrete are taken into account. The analysis results show that the predicted strength of the failure criterion is in good agreement with the basic requirements of continuity, smoothness and convexity and better reflects the dynamic strength change rule of ordinary concrete. Meanwhile, the strength criterion can be obtained just by the typical stress points, thus it has a simple expression form and is convenient for practical application to analysis of engineering structures.