# Design and Simulation Analysis of a New Type of Assembled UHPC Collision Avoidance
## 3 Performance Analysis of Design Parameters
### Performance Analysis of UHPC Floating Tank Wall Thickness Parameters  
In view of the fact that this study is based on the Honghe Bridge project in Zhuhai and considering the safety and applicability of the UHPC floating box as well as the economy of the project construction, it is particularly important to determine the thickness of the wall of the new UHPC collision avoidance device. In this section, three different wall thickness parameter, h, values are compared and analyzed: Condition B1: h = 150 mm, Condition B2: h = 120 mm, and Condition B3: h = 90 mm. In Figure 20, it can be seen that the total energy of the system remains unchanged, which satisfies the law of conservation of energy. The hourglass energy, slip energy, and total energy absorbed by the piers of the system vary little under the three conditions, and all fluctuate over a relatively small range. The slip energy values for Conditions B1, B2, and B3 are 17.7 MJ, 18.9 MJ, and 18.8 MJ, respectively. The slip energy is increased by 40.5%, 50.0% and 49.2%, respectively, compared with the  
Figure 19: Collision avoidance performance of the device under different material support elements. Figure 18: Impact force time-history curve of the pier. unprotected condition where the slip energy is 12.6 MJ, which indicates that the components of the collision avoidance device produce very large friction energy dissipation during the collision process, which is consistent with reality. The total energy absorbed by the device deformation is obviously less than that absorbed by the device under Conditions B2 and B3. This shows that, when the wall thickness of the UHPC float box is 150 mm, the rigidity of the collision avoidance device is large, the plastic deformation volume of the bow is the largest, the damage deformation is serious, and the flexible energy dissipation performance of the device cannot be fully utilized. Therefore, the energy dissipation performance values of Condition B2 and Condition B3 are better than that of Condition B1 in terms of energy and ship protection. From Figure 21 it can be seen that the bow collision depth curves under the three conditions reach their peak values at approximately 1.0 s, which are 1.5 m, 1.40 m, and 1.38 m, respectively. Compared with the bow collision depth value of 3.06 m under the unprotected conditions, the bow collision depth can be reduced by more than 50%. This shows that the collision avoidance device can significantly reduce the bow collision depth to achieve the effect of ship protection. Figure 22 presents the equivalent stress curves on the pier during the ship-bridge collision and shows that the maximum equivalent forces on the pier's under the three conditions are 38.2 MPa, 32.9 MPa and 48.9 MPa. Under the three conditions of the collision avoidance device, the maximum equivalent stress on the pier decreases greatly and the curve changes more smoothly, which shows that the device can play a good cushioning and energy dissipation role, and the rubber slider can improve the stress concentration phenomenon in the impact area and prevent local damage to the pier. Figure 21: Bow impact depth time-history curve. Figure 20: Energy comparison and summary of the three different wall thicknesses under protected conditions. Figure 23 presents the time-history curves of the impact force on the pier under the three protected conditions and the unprotected condition. It can be seen in this figure that for Condition B1, the peak value of the impact force is 26.27 MN at 2.20 s. The reduction in the impact force is 25.6% while the impact duration is extended by 76%. For Condition B2, the impact force reaches its peak value of 22.5 MN at 0.78 s. The maximum reduction of the impact force is 36.3%. The impact duration is prolonged by 46.4% to 1.83 s. For Condition B3, the peak value of the impact force is 23.26 MN. The impact force is reduced by 34.1%, the impact duration is 1.70 s, and thus, the impact duration is prolonged by 26.5%.