## 5 Conclusions  
The dynamic mechanical properties of BFRC were investigated by using a SHPB apparatus. The influence factors including confining pressure, fiber content and temperature were analyzed. A new constitutive model was established and its practicability was proved. Based on the experimental results and the analyses, the following conclusions can be drawn:  
* At different temperatures, the optimum fiber content of BFRC is different. When the fiber content is between 0.1% and 0.3%, BFRC has higher dynamic strength and ductility. The mechanical properties of BFRC can't reach the optimal level whether the fiber content is too low or too high.
* The dynamic peak stresses of BFRC specimens gradually reduce and the crush degree increases as the temperature rises. High temperature has a remarkable damage effect on the dynamic mechanical properties of concrete, especially when the temperature is above 400 \({}^{\circ}\)C, the peak stress will be greatly reduced. However, the peak strength decreased less than 20% when the temperatures ranged from 20 \({}^{\circ}\)C to 400 \({}^{\circ}\)C.
* The confining pressure has a noticeable effect on the dynamic mechanic properties of BFRC. It can improve the dynamic peak stress, ductility and dynamic elastic modulus, change the crushing morphology and reduce the degree of crushing fragment.
* Compared with the ZWT model, the visco-elastic damage constitutive model was established in this paper can fit with test curves very well with fewer parameters, so the V-E model has better practicability.  
**Author Contributions:** Conceptualization: W.L. and J.Z. Methodology: W.L., Y.L. and Y.Z. Formal analysis: W.L., Y.L., Z.W. and Y.Y. Writing--original draft preparation: W.L. Writing--review and editing: W.L. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This work was carried out in School of Civil Engineering at Chang'an University, and supported by the Postdoctoral Science Foundation Project of China (2020T130567, 2016M602736), and the Fundamental Research Funds for the Central Universities, CHD (300102269107), Natural Science Foundation of Shaanxi Province (2020 JQ-373), National Natural Science Foundation of China (No. 51878056), Social Development Foundation for Science and Technology Planning Project of Shaanxi Province (2019 SF-256).  
**Conflicts of Interest:** The authors declare no conflict of interest.  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**Temperature** & **Fiber** & **Impact** & & & & & & & \\
**Content** & **Content** & **Velocity** & \(m\)** & \(a\) & \(E_{0}\)**(GPa)** & \(E_{1}\)**(GPa)** & \(\varphi_{1}\)**(s)** & \(E_{2}\)**(GPa)** & \(\varphi_{2}\)**(\(\times 10^{-6}\)**s)** & \(R^{2}\) \\ (\%C) & (\%) & (\%) & & & & & & & & \\ \hline
200 & 0.2 & 8.8 & 1.03 & 0.0074 & 3.70 & 5.50 & 26.86 & 16.1 & 26.81 & 0.94 \\ \hline
400 & 0.2 & 8.8 & 1.02 & 0.0073 & 2.29 & 3.30 & 53.03 & 20.0 & 44.80 & 0.90 \\ \hline
600 & 0.2 & 8.8 & 1.60 & 0.0007 & 1.10 & 2.10 & 66.67 & 9.0 & 100.0 & 0.98 \\ \hline
800 & 0.2 & 8.8 & 1.71 & 0.0007 & 1.18 & 1.71 & 78.86 & 7.0 & 35.89 & 0.98 \\ \hline \hline \end{tabular}
\end{table}
Table 5: _Cont._