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.