# Safety Performance Evaluation of Ultra-High-Performance Concrete Semi-Assembled Barrier
## 5 Analysis of the Crash Simulation Results
### Barrier Guiding Ability  
The Standard for Safety Performance Evaluation of Highway Barriers (JTG B05-01-2013) proposes that if the vehicle does not overturn after the collision and the wheel track after the vehicle leaves the departure point does not cross the straight-line F when passing through the guidance exit frame, the barrier guidance function is considered to be good (Figure 6). The reliability of the numerical simulation was qualitatively evaluated by comparing the trajectory obtained from the full-scale vehicle crash test with that obtained from the numerical simulation. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Type**} & \multicolumn{8}{c}{**Parameters**} & \multirow{2}{*}{\(F_{Xmax}\)/kN} \\ \cline{2-2} \cline{4-9}  & **m/kg** & & & & & & & & \\ \hline Car & 1500 & 27.78 & 20 & 1.8 & 0.875 & 0 & 189 & 182 & 3.8\% \\ Bus & 10,000 & 22.22 & 20 & 4.2 & 1.225 & 0 & 333 & 307 & 7.8\% \\ Truck & 18,000 & 16.67 & 20 & 4.5 & 1.250 & 0 & 313 & 324 & 3.4\% \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Parameters of Equation (11). Where  
\[\text{For car A = 2.2 + V}_{\text{W}}+0.16\ \text{V}_{\text{L}}\ (\text{m})\text{; B = 10 (m)} \tag{12}\]  
For bus and truck A = 4.4 + V_{\text{W}}+0.16\ \text{V}_{\text{L}}\ (\text{m})\), B = 20 (m) (13)  
V\({}_{\text{W}}\)--Total width of the vehicle (m); V\({}_{\text{L}}\)--total length of the vehicle (m). 1. A 1.5-ton car  
Figure 7 shows a comparison of the full-scale vehicle crash test results with the vehicle trajectory obtained from the numerical simulation. The car began to collide with the barrier at 0.02 s. The wheel climbed up along the inclined surface of the lower part of the barrier. The car began to turn owing to the blocking effect of the barrier. At 0.15 s, the front of the car completed the steering and slipped along the slope, away from the barrier. Simultaneously, owing to the inertia of the car body, a tail flick occurred, the rear side of the car body rebounded after colliding with the barrier, and the car continued to move forward by turning the left front wheel. Subsequently, the car fell back to the ground in approximately 0.8 s, owing to its gravity. Figure 6: Vehicle track guided exit frame for a standard section of barrier. Figure 7: Comparison of test and simulation of vehicle trajectory for the car. Over the entire process, the vehicle moved away quickly, and there was no phenomenon of overriding or riding over the barrier. The simulation results of the vehicle trajectory agree well with the experimental results. However, the vehicle traveled differently after the collision with the barrier. In the full-scale vehicle crash test, the car gradually moved away from the barrier after the collision and continued to travel along the exit angle. In the numerical simulation (Figure 8), the car traveled longitudinally along the barrier after the collision. The main reason for this difference is that in the numerical simulation, the right front wheel was held dead after the collision with the barrier and could not continue to rotate, resulting in the vehicle not being able to control the steering and could only move forward under the effect of inertia. This phenomenon may occur in actual collisions, that is, vehicle collisions may cause tire blowouts or vehicle steering lockups. According to the calculation in Equation (12), for a 1.5-t car, A = 4.71 m, B = 10 m. The trajectory of the car is illustrated in Figure 8. Following the collision with the barrier, the car did not deviate from the guiding exit frame, nor did it pose a threat to adjacent vehicles in the same direction. This indicates that the barrier effectively served its guiding function. 2A 10-ton medium bus  
Figure 9 compares the collision barrier of the medium-sized bus with the barrier, showing the vehicle trajectory obtained from numerical simulation. After colliding with the barrier, the right front wheel of the bus climbed along the slope of the collision surface of the barrier, causing deformation of the front bumper.