基于均匀化理论的混杂纤维混凝土有效弹性模量计算

Calculation of Effective Elastic Modulus for Hybrid Fiber Reinforced Concrete Based on Homogenization Theory

混杂纤维混凝土是典型的多相多层次非均质复合材料,在弹性阶段其宏观尺度力学行为由细观、微观乃至纳观组成与结构决定。为探究材料微细观结构对宏观尺度力学性能的影响,在微细观力学框架下,基于Mori-Tanaka法和三相模型,建立了考虑界面作用的钢-聚丙烯混杂纤维混凝土弹性模量的多尺度均匀化理论模型,在经过试验结果验证的基础上,进行了影响因素拓展分析。结果表明:钢纤维的掺入提高了混凝土弹性模量,其提高幅度随钢纤维体积掺量的增大而增大,而聚丙烯纤维的掺入对弹性模量的影响不大;混杂纤维混凝土弹性模量随纤维界面弹性模量的增大而增大,且纤维掺量越大其增大幅度越大;增大钢纤维和聚丙烯纤维界面厚度均会减小其弹性模量;骨料体积分数是影响整体弹性模量的主要因素,表现在骨料所占体积越大,材料整体弹性模量也越大。

Hybrid fiber reinforced concrete(HFRC)is a typical multi-scale heterogeneous composite material and its macro-scale mechanical behavior at elastic stage is determined by its meso-,micro-and nano-components and structures.In order to explore the influence of microstructure at smaller scales on the macro-scale mechanical properties,a multi-scale homogenization theory model considering the interface effect for predicting the elastic modulus of steel-polypropylene(PP)hybrid fiber reinforced concrete was proposed based on the Mori-Tanaka method and three-phase model.The theoretical data from this model is in reasonable agreement with the experimental results from the reported literatures,thus proving the validity of this model.In the comparative analysis,the addition of steel fiber can enhance the elastic property of concrete slightly and the enhancing effect develops with the increase of fiber dosage,while the effect of PP fiber is negligible.Moreover,the elastic modulus of HFRC improves with the increase of the fiber interface property but reduces slightly with the increase of the fiber interface thickness.In addition,the aggregate volume fraction is another important factor affecting the HFRC elastic property:the larger the aggregate volume,the greater the HFRC modulus.