混凝土随机损伤本构模型研究新进展

为了方便活性粉末混凝土(Reactive Powder Concrete，RPC)等效矩形应力图系数与塑性损伤因子的计算与取值，对RPC应力-应变曲线系数与塑性损伤因子的计算模型进行了理论研究。通过对现有的计算方法进行无量纲化转化，推导了决定计算模型的四个原函数条件；对一个实际的应力-应变关系进行了计算，将得到的结果进行了分析；并对受弯矩形梁非极限状态下截面内力和力矩的推定计算进行了演示。针对应力-应变关系式含有非整次有理分式的情况提出了曲线拟合方法；研究了拟合次数、拟合区间和拟合函数类型对拟合精度与稳定性的影响。比较了4种典型的RPC本构模型在同种材料下的应力-应变曲线系数与损伤因子取值模型曲线，结果显示：拟合曲线得到的取值模型与其他原始曲线得到的取值模型在曲线上具有较高的相似度，证明了曲线拟合方法的准确可靠性；最后给出了一种RPC受压应力-应变曲线系数与塑性损伤因子无量纲化取值模型。

Advances in researches on stochastic damage models of concrete

In order to facilitate the calculation and utilization of the equivalent rectangular stress-strain diagram coefficients and plastic damage parameter of reactive powder concrete (RPC), a theoretical study on the calculation model of RPC stress-strain curve coefficients and plastic damage parameter has been conducted. By nondimensionalizing the existing calculation methods, 4 indefinite integrals that determine the calculation model are deduced. A practical stress-strain relationship was calculated, and the results obtained were analyzed; and the presumptive calculation of internal forces and moments on the cross section of a cantilever beam in the non-limit state was demonstrated. A curve fitting method is proposed for the case where the stress-strain relation contains non-integer rational fractions, and the effects of fitting times, fitting intervals and fitting function types on fitting accuracy and stability were studied. The stress-strain curve coefficients and damage parameter value model of 4 typical RPC constitutive models under the same material were compared, and the result shows that: the value models obtained from fitting curves and obtained from other original curves have high similarity on the curve shape, which proves the accuracy and reliability of the curve fitting method. Finally, a dimensionless calculation model for RPC compressive stress-strain curve coefficients and plastic damage parameter is developed.