The 3-D base force element method (BFEM) for damage problems is proposed, which is applied to analyze the damage mechanism of recycled aggregate concrete (RAC). A piecewise curve damage constitutive model is given to simulate the constitutive relationships of RAC phases. A spatial random aggregate model of RAC is proposed. 3-D numerical simulations of RAC under uniaxial mechanical stress are carried out. The macroscopic stress–strain relationship and failure process of RAC under uniaxial stress based on the 3-D BFEM are obtained. The numerical results show a good consistency with the experimental results. This illustrates that the numerical simulation can reflect the nonlinearity deformation, stress redistribution, and crack propagation process of RAC. In addition, the influence of recycled aggregate replacement percentage on strength and elastic modulus is investigated. The results show that the content proportion of recycled aggregate has a great effect on RAC, which have to be considered in the analysis and the application of RAC.

中文翻译：

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再生混凝土细观损伤分析的三维基础力元法

提出了损伤问题的三维基础力元法（BFEM），用于分析再生骨料混凝土（RAC）的损伤机理。给出了分段曲线损伤本构模型来模拟RAC各相的本构关系。提出了RAC的空间随机聚合模型。进行了单轴机械应力下 RAC 的 3-D 数值模拟。基于3-D BFEM得到了RAC在单轴应力作用下的宏观应力-应变关系和失效过程。数值结果与实验结果具有良好的一致性。这说明数值模拟可以反映RAC的非线性变形、应力重新分布和裂纹扩展过程。此外，研究了再生骨料置换率对强度和弹性模量的影响。结果表明，再生骨料的含量比例对RAC的影响很大，在RAC的分析和应用中必须考虑到这一点。