混凝土是一种介于理想固体与流体之间,与加载龄期和持荷时间有关的徐变材料。针对分数阶微积分可描述处于理想固体与流体之间不同状态的流变行为,建议将分数阶模型应用于混凝土徐变模型分析。首先基于带软体元件的广义开尔文模型,建立了5参数分数阶徐变模型;接着结合复合形优化算法反演出混凝土分数阶徐变模型的5个参数。工程算例分析表明,分数阶徐变模型计算值与试验值吻合效果良好,且与8参数模型拟合效果相当,将分数阶流变模型应用在混凝土徐变中为混凝土徐变分析提供了一种新思路。

Concrete, a creep material between ideal solid and fluid, is related to loading age and load-bearing time. In this article, the fractional order calculus model is applied to the analysis of concrete’s creep. A fractional order creep model with five parameters is established based on the generalized Kelvin model with software components. Furthermore, according to measured creep values of three engineering cases, the five parameters of the established fractional order creep model are inverted and optimized by using the complex optimization algorithm. The expressions of concrete creep model in consideration of loading age are given. Engineering case study demonstrates that the calculated values of the fractional order model agree well with test values, close to those of eight-parameter model. Fractional order model could be a new approach in creep analysis of concrete.