Influence of blocking ratio on hydrodynamic force on deep-water pier under earthquake

The deep-water bridge would suffer more serious damage under earthquake than that standing in air. The larger blocking ratio has remarkable effect on the added mass coefficient, which deserves a further and comprehensive study. The generation mechanism of block effect is analyzed by using the numerical simulation software ANSYS Fluent. Results show that the recirculation zone with focus decreases the pressure on the rear surface of the cylinder, results in the peak value of the in-line force does not occur synchronously with the peak value of acceleration. Results also indicate that the change of the position and intensity of the recirculation zone with focus, as well as the change of the water flow around the cylinder surface, are the generation mechanism of the block effect, the block effect has a 10% influence on the hydrodynamic force. The added mass coefficient changing rule with blocking ratio is then discussed elaborately, and the modification approach to the present added mass coefficient calculation method is suggested. Finally the physical experiments are conducted to validate the modification approach, results shows the modification approach is accurate and can be used both in the further study and in real practice.

Automated summary

The deep-water bridge is more vulnerable to earthquake damage than the bridge standing in air. The larger blocking ratio has a significant impact on the added mass coefficient, which requires further comprehensive study. The generation mechanism of block effect is analyzed using numerical simulation software ANSYS Fluent. The results show that the recirculation zone with focus reduces the pressure on the back surface of the cylinder, resulting in the peak value of in-line force not occurring synchronously with the peak value of acceleration. The change in position and intensity of the recirculation zone with focus, as well as the change in water flow around the cylinder surface, are identified as the generation mechanism of the block effect, which has a 10% influence on the hydrodynamic force. The changing rule of the added mass coefficient with blocking ratio is discussed in detail, and a modification approach to the current added mass coefficient calculation method is suggested. Physical experiments are conducted to validate the modification approach, and the results show that it is accurate and can be used in further study and real practice.