废弃纤维再生混凝土非线性蠕变模型

为研究废弃纤维再生骨料混凝土的蠕变过程，引入一个非线性黏性元件，与经典Burgers模型串联组成五元件六参数非线性蠕变模型。通过对废弃纤维再生骨料混凝土的拉伸蠕变试验，得到了不同体积率纤维掺量以及不同再生骨料取代率混凝土的拉伸蠕变柔度随加载时间的变化规律。参照蠕变模型中蠕变柔量与时间的关系式，通过基于Levenberg-Marquardt优化算法的混凝土蠕变参数识别，得到混凝土非线性蠕变模型的六个力学参数。模型拟合结果与试验结果一致，表明该模型能够较好地反映废弃纤维再生骨料混凝土的蠕变特性，也表明掺入0.12%体积率废弃聚丙烯纤维与50%再生骨料取代率的混凝土具有较好的经济实用价值。

Study on nonlinear creep model of recycled fiber-reinforced concrete

The nonlinear viscous element is introduced to study the creep process of recycled aggregate concrete. It is combined in series with the classic Burgers model to form a five-element six-parameter nonlinear creep model. Tensile creep tests are conducted on the recycled aggregate concrete with different fiber volume fractions and different replacement rates of recycled aggregate to investigate the variation of tensile creep compliance with loading time. Referring to the relationship between creep compliance and time in the creep model, the six mechanical parameters of the concrete''s nonlinear creep model are identified through the optimization algorithm based on Levenberg-Marquardt. The fitting results of the model are consistent with the experimental results, indicating that the model can well reflect the creep characteristics of recycled aggregate concrete. It also shows that concrete with 0.12% volume fraction of recycled polypropylene fiber and 50% replacement rate of recycled aggregate has good economic practical value.