This study explores the ballistic impact resistance of Ultra-High Performance Concrete (UHPC) through an extensive and detailed experimental investigation. This study will address various gaps related to the impact performance of UHPC. This investigation focused on understanding the ballistic resistance performance of UHPC based on (a) the influence of projectile/bullet parameters (hardness, velocity/energy, diameter, and nose shape), (b) the effect of hybrid fibers, (c) comparative analysis of the use of steel mesh and reinforcement bars and (d) effect of sub-zero temperature. In this parametric investigation, different types and shapes (flat, conical, and ogive) of hardened steel projectiles (diameter 12 and 18 mm) with impact velocities ranging from 103 to 182 m/s or impact energy ranging from 674 to 2103 J and UHPC slabs with thickness ranging from 36 to 100 mm was considered. Steel mesh and reinforcement bars at different spacing (with and without fiber UHPC) were also assessed, along with the effect of sub-zero temperature of −30 °C. The impact energy of the projectile and thickness of UHPC targets were statistically significant parameters affecting penetration depth in UHPC compared to other parameters with a p-value much less than 0.001. The Artificial Neural Network (ANN) model developed in the study could predict the penetration depth with reasonable accuracy (MAPE and RMSE were observed to be 7.69 and 12.12, respectively). The experimental results of this study will provide insights into the development of guidelines for using UHPC as a protective material, which can help ensure the safety and resilience of infrastructures in the face of potential threats.

中文翻译：

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超高性能混凝土 (UHPC) 的抗弹道冲击性：综合实验研究和参数分析

本研究通过广泛而详细的实验研究探索了超高性能混凝土 (UHPC) 的抗弹道冲击性能。这项研究将解决与 UHPC 冲击性能相关的各种差距。这项研究的重点是了解 UHPC 的防弹性能，基于 (a) 射弹/子弹参数（硬度、速度/能量、直径和鼻部形状）的影响，(b) 混合纤维的影响，(c) 比较分析钢网和钢筋的使用以及（d）零下温度的影响。在此参数研究中，不同类型和形状（扁平、圆锥形和尖顶）的硬化钢弹丸（直径 12 和 18 mm），冲击速度范围为 103 至 182 m/s 或冲击能量范围为 674 至 2103 J 和 UHPC考虑了厚度范围为 36 至 100 毫米的板坯。还评估了不同间距的钢网和钢筋（有和没有纤维 UHPC），以及 -30 °C 零下温度的影响。与 p 值远小于 0.001 的其他参数相比，弹丸的冲击能量和 UHPC 目标的厚度是影响 UHPC 穿透深度的统计显着参数。研究中开发的人工神经网络 (ANN) 模型可以以合理的精度预测穿透深度（MAPE 和 RMSE 分别为 7.69 和 12.12）。这项研究的实验结果将为制定使用UHPC作为防护材料的指南提供见解，这有助于确保基础设施在面临潜在威胁时的安全性和恢复能力。