Ultra-high performance concrete (UHPC) features with exceedingly high strength and fracture energy, and thus is regarded as a promising structural material to resist impact and blast loadings. Particularly, adding steel fibers can significantly enhance the impact resistance of UHPC. To facilitate the simulation of the behavior of UHPC structures with various steel fiber ratios against extreme loadings, selecting an appropriate constitutive model and determining its parameters should be highly emphasized. The Holmquist-Johnson-Cook (HJC) model is widely used in the simulation of the conventional concrete subjected to impact and explosion, whereas there are rare studies on calibrating the parameters of the HJC model for UHPC. In this study, a set of HJC model parameters for UHPC with considering the volume ratio of steel fiber ranging from 0% to 3% were firstly determined based on existing test data, originating from the Split-Hopkinson pressure bar (SHPB) test, triaxial test, uniaxial loading test, and Hugoniot test. To verify the correctness of the calibrated parameters of HJC model, UHPC slabs under the contact explosion condition were then tested, and a finite element model (FEM) with the calibrated parameters implemented was thereby established to reproduce this experiment numerically. Finally, the existing bullet penetration experiment was also verified with the numerical procedure. The results show that finite element simulations by employing the HJC model with calibrated parameters agree well with the experiments. The successful applications and evaluation of the HJC model with calibrated parameters in this work can provide guidance in simulating the behavior of UHPC with certain prescribed steel fiber ratio subjected to the impact and blast loading.

超高性能混凝土（UHPC）具有极高的强度和断裂能，因此被认为是一种很有前途的抗冲击和爆炸载荷的结构材料。特别是加入钢纤维可以显着提高UHPC的抗冲击性。为了便于模拟具有各种钢纤维比率的 UHPC 结构在极端载荷下的行为，应高度重视选择合适的本构模型并确定其参数。Holmquist-Johnson-Cook (HJC) 模型广泛用于模拟常规混凝土受到冲击和爆炸的影响，而对于 UHPC 的 HJC 模型参数标定的研究很少。在这项研究中，基于现有的试验数据，首先确定了一套考虑钢纤维体积比为0%~3%的超高性能混凝土HJC模型参数，源自Split-Hopkinson压力棒（SHPB）试验、三轴试验、单轴加载测试和 Hugoniot 测试。为验证HJC模型标定参数的正确性，对接触爆炸条件下的UHPC板进行了试验，建立了采用标定参数的有限元模型（FEM），对该实验进行了数值模拟。最后，还用数值程序验证了现有的子弹穿透实验。结果表明，采用带标定参数的HJC模型进行有限元模拟与实验吻合较好。