This paper deals with numerical analysis on the mechanical behavior of ultrahigh performance concrete (UHPC) under uniaxial compression. For the modeling of the mechanical behavior of UHPC, the mesh-free discrete element method was applied. To calibrate the model parameters and validate the numerical simulation results, a set of experimental investigations including mechanical tests, microscopy and tomography analysis, were performed. The scanning electron microscopy and polarized light microscopy were used to examine cross sections of UHPC as well as to characterize interfacial transition zone and aggregate in detail. X-ray microtomography analysis was used to obtain information about the nonspherical shape of aggregate and to generate a realistic structural model. Simulation results have shown that the developed model predict stiffness reliably, strength, and breakage pattern of UHPC and shows good agreement with experimental results. Finally, the model has been applied to analyze the main crack initiation in static failure and to investigate the influence of different parameters such as aggregate content as well as aggregate and binder stiffness on the mechanical behavior of UHPC.

中文翻译：

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基于三相离散元模型的超高性能混凝土力学行为数值研究

本文对超高性能混凝土 (UHPC) 在单轴受压下的力学行为进行数值分析。对于 UHPC 的力学行为建模，应用了无网格离散元方法。为了校准模型参数并验证数值模拟结果，进行了一系列实验研究，包括机械测试、显微镜和断层扫描分析。扫描电子显微镜和偏光显微镜用于检查 UHPC 的横截面以及详细表征界面过渡区和聚集体。X 射线显微断层扫描分析用于获取有关骨料非球形形状的信息并生成真实的结构模型。仿真结果表明，所开发的模型可以可靠地预测刚度，UHPC 的强度和断裂模式，与实验结果有很好的一致性。最后，该模型已应用于分析静态失效中的主要裂纹萌生，并研究了不同参数（如骨料含量以及骨料和粘合剂刚度）对 UHPC 力学行为的影响。