Study on the hydrodynamic added mass of rectangular pier under sine wave actions

Abstract

As for deep-water bridges in river, sea, and reservoirs, the water-structure interaction is non-negligible when investigating its seismic performance. Morison equation and radiation wave theory are two main methods for calculation of hydrodynamic pressure resulted from water-structure interaction, which cannot truly simulate the complicated interaction between water and structures. This study conducts a series of underwater shaking table tests on seven rectangular steel tubes to predict the hydrodynamic added mass of rectangular piers considering water-pier interaction. The influence of action amplitude, action frequency, water depth, depth of cross section, and width of upstream face of the pier on hydrodynamic added mass is investigated. The results show that the hydrodynamic added mass of pier first decreases and then increases with action frequencies. The hydrodynamic added mass is proportional to a-th (a > 1) power of water depth due to the influence of structures on the movement of water. The hydrodynamic added mass increases with depth of cross section and width of upstream face of pier, and changes slightly with the action amplitude with maximum percentage of 10% and thus can be neglected. Therefore, except for the water depth, depth of cross section, and width of upstream face, the frequency characteristics of ground motions should be considered when analyzing the water-pier interaction under earthquake actions.