纤维混凝土受压细观统计损伤本构模型研究

Research on meso stochastic damage constitutive model of fiber concrete under compression

分别对31个普通混凝土试块、38个钢纤维混凝土试块及11个聚丙烯纤维混凝土进行了单轴受压本构试验研究,采用卡方检验方法对试验结果进行统计分析及假设检验,确定了以峰值应变为损伤变量的概型分布.基于唯象细观统计损伤力学及热力学的相关理论,在传统模型基础上引入了损伤阈值概念,并研究了不同混凝土损伤阈值取值问题.同时,探讨了塑性应变对本构模型的影响,建立了考虑塑性应变及损伤阈值的纤维混凝土单轴受压细观统计损伤本构模型.研究结果表明:损伤变量较好的服从Weibull分布函数;普通混凝土损伤阈值γ为0.6倍峰值应变,掺入纤维后,损伤阈值γ提高为0.8倍峰值应变;所建立的本构模型能够有效地描述纤维混凝土的受压本构关系.

The stress-strain relationship experiments of different concrete under uniaxial compression were studied. The results of stress-strain experiments were analyzed by the method of Chi-square testing that the probability distribution of damage variable and related parameters were determined. The introduction of damage threshold based on the traditional Weibull random distribution of two parameters, and the range of damage threshold was discussed. Meanwhile, the influence of plastic strain on the constitutive model was discussed, and the meso stochastic damage constitutive model of fiber concrete under compression were established according to the phenol- menological microscopic statistical damage mechanics and thermodynamic theory. Results showed that the damage variable obeyed Weibull distribution, and the damage threshold of fiber concrete was greater than ordinary concrete. The given model of this paper helped describe the stress-strain curve of fiber concrete under uniaxial compression.