Lots of experiments observe the size-dependent phenomena of concrete mechanical behaviors. In this paper, the micropolar theory is adopted to describe the size effects by introducing two size-related parameters into their constitutive equations, named coupling number and characteristic length . A micropolar damage model is built for size-dependent concrete fracture problems utilizing the bond-based peridynamic (PD) idea. That is, the material damage and fracture behaviors are determined by the local damage factors of the PD bonds. Then, the tensile strength of a concrete specimen is numerically estimated by the PD differential operator (PDDO) method. The influences of the size parameters and on the tensile strength are studied. By comparing with the transformed Bažant size-effect law and the fitting error analysis, the reasonable values of and are determined for a certain reinforced concrete composite. Finally, by using the determined micropolar damage model, the crack propagation paths in concrete members are numerically simulated.

中文翻译：

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PDDO 方法模拟尺寸相关混凝土断裂问题和裂纹扩展的微极损伤模型


大量实验观察了混凝土力学行为的尺寸相关现象。本文采用微极性理论来描述尺寸效应，在其本构方程中引入两个与尺寸相关的参数，即耦合数和特征长度。利用基于粘结的近场动力学 (PD) 思想，针对尺寸相关的混凝土断裂问题建立了微极损伤模型。也就是说，材料的损伤和断裂行为是由PD键的局部损伤因素决定的。然后，通过 PD 微分算子 (PDDO) 方法对混凝土试件的抗拉强度进行数值估算。研究了尺寸参数和抗拉强度的影响。通过与变换后的Bažant尺寸效应定律的比较和拟合误差分析，确定了针对某钢筋混凝土组合物的合理的值。最后，利用确定的微极性损伤模型，对混凝土构件中的裂纹扩展路径进行数值模拟。