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混凝土材料细观单元弹模非均匀统计特性研究

ISSN号：1000-4750
期刊名称：工程力学
时间：0
页码：106-115
分类：TU528.1[建筑科学—建筑技术科学]
作者机构：[1]北京工业大学城市与工程安全减灾教育部重点实验室,北京100124
相关基金：国家自然科学基金重点项目（90715041,50838001）; 973计划项目（2011CB013600）; 北京市重大项目（8100001）; 北京工业大学博士生创新基金（YB201207）
相关项目：钢筋混凝土构件破坏机理与尺寸效应研究

作者：杜修力|金浏|

关键词：混凝土, Voigt并联模型, 单元等效弹性模量, WEIBULL分布, Kolmogorov检验, 特征单元尺度, concrete, Voigt parallel model, element equivalent elastic modulus, Weibull distribution, Kolmogorov test, characteristic element scale

中文摘要：

假定混凝土是由骨料颗粒及砂浆基质组成的复合材料,基于Voigt并联模型对混凝土细观单元进行等效化,对单元的等效弹性模量进行统计分析。以Weibull分布为假设分布,采用图解法结合逐步回归优选法进行参数估计,探讨了混凝土细观单元弹性模量的分布形式,并根据Kolmogorov非参数检验,对假设分布进行了检验;对不同尺度下的细观单元弹性模量进行统计分析,并对骨料空间分布随机性的影响作了初步分析;最后对不同级配下混凝土材料的特征单元尺度问题进行了研究。结果表明：1）混凝土细观单元弹性模量的随机分布形式及参数具有尺度效应,且并不完全服从Weibull模型;2）混凝土细观单元弹性模量的变异性与尺度相关,随单元尺度的减小,变异性先随之增大后逐渐趋于稳定,它反映了混凝土材料细观不均匀程度存在一个合理的细观尺度表述的事实,对应于变异系数向平稳段过渡的拐点所对应的单元尺度称为特征尺度;3）二级、三级、四级配下混凝土材料的特征单元尺度分别为10mm、15mm和18mm;4）骨料空间分布的随机性对细观单元弹性模量随机分布特征影响可以忽略。

英文摘要：

Concrete was assumed to compose of aggregate particles and a mortar matrix, and the concrete unit was processed equivalently based on the Voigt parallel model in the paper. The distribution of equivalent elastic modulus of a meso-unit was studied, based on the Weibull distribution, and a graphical method and the stepwise regression were applied to optimizing the estimated parameters. Furthermore, the validity of the assumed distribution was examined by the Kolmogorov test. The statistical parameter of element Young＇s modulus with different element-scale, and the spatial distribution randomness of aggregate were studied in the paper. The problem on material characteristic element scale of concrete of different grade-level was analyzed at the end of the paper. The analytical results indicate that： l） the form and the parameters of random distribution of elastic modulus of a concrete meso-scale unit have size effects, and not fully obey the Weibull distribution. 2） the variability of elastic modulus of a concrete meso-element associates with scales; and the variability increases firstly and tends to be stable gradually with the decrease of element size, which reflects the facts that there exists a reasonable representation of non-uniform degree of concrete at meso level. The reasonable scale, i.e. the variation coefficients tending to the inflection point of a smooth transition to the corresponding scale, is defined as a characteristic element scale. 3） The characteristic element scale of concrete material on two-grade, three-grade and four-grade are 10mm, 15mm and 18mm, respectively. 4） The spatial distribution randomness of aggregate has little effects on random distribution properties of elastic modulus of a concrete meso-unit.

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