静动组合载荷下混凝土率效应机理及强度准则

发布时间：2018-03-20 16:46

本文选题：混凝土　切入点：应变率　出处：《力学学报》2017年04期 　论文类型：期刊论文

【摘要】：混凝土结构在受到动载荷作用之前,通常已承受着初始静载荷的作用.大量关于混凝土应变率效应的研究均没有考虑初始静载荷对动强度的影响,会导致过高地估计混凝土的动强度,使混凝土结构设计偏于危险.本文通过分析混凝土材料在静动组合载荷下的率效应机理,给出了初始静载荷的定义.在此基础上,推导了混凝土材料参数与初始静载荷和应变率的表达式,提出了建立静动组合强度准则的一般方法.通过材料参数反映初始静载荷与应变率的联合影响,给出了由初始有效静载荷、动态黏聚强度和摩擦强度共同组成的混凝土动态强度,将广义非线性强度准则发展为静动组合多轴强度准则.建立的强度面在相同初始静载荷下随应变率的增大向外扩张,在相同应变率下随初始静载荷的增大向里收缩,即混凝土的强度在相同初始静载荷下随应变率的增大而增大,在相同应变率下随初始静载荷的增大而减小.此外,当初始静载荷和应变率不变时,加载路径对混凝土材料的应变率效应无影响,但会影响混凝土材料的静水压力效应,即当初始静载荷和应变率固定不变时,静动组合强度面的位置和大小即可确定,不同加载路径下强度的不同是由于静水压力效应导致的.最后利用多组混凝土材料静动组合强度试验对建立的静动组合强度准则进行了验证.
[Abstract]:Concrete structures are usually subjected to initial static loads before they are subjected to dynamic loads. Many researches on the strain rate effect of concrete do not consider the effect of initial static loads on dynamic strength. The dynamic strength of concrete will be overestimated, and the design of concrete structure will be more dangerous. In this paper, the definition of initial static load is given by analyzing the mechanism of rate effect of concrete material under static and dynamic combined loads. The expressions of concrete material parameters and initial static load and strain rate are derived, and a general method of establishing static and dynamic combined strength criterion is proposed. The combined effect of initial static load and strain rate is reflected by material parameters. The dynamic strength of concrete composed of initial static load, dynamic cohesion strength and friction strength is given. The generalized nonlinear strength criterion is developed into the multiaxial strength criterion of static and dynamic combination. The strength surface expands outward with the increase of strain rate under the same initial static load, and shrinks inward with the increase of initial static load at the same strain rate. That is, the strength of concrete increases with the increase of strain rate under the same initial static load, and decreases with the increase of initial static load at the same strain rate. The loading path has no effect on the strain rate effect of concrete material, but it will affect the hydrostatic pressure effect of concrete material. That is, when the initial static load and strain rate are fixed, the position and size of the static and dynamic strength surface can be determined. The difference of strength under different loading paths is caused by hydrostatic pressure effect. Finally, the static and dynamic combined strength criterion is verified by the static and dynamic combined strength test of many groups of concrete materials.
【作者单位】：北京工业大学城市与工程安全减灾教育部重点实验室;
【基金】：国家自然科学基金(51522802,51421005) 国家重点研发计划(2016YFC0701104)资助项目
【分类号】：TU528

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