Abstract: The underwater shaking table enriches and broadens the application of shaking tables in the seismic research of engineering structures, but its vibrating water behaviors are often distorted due to its local vibration and the interference of its tarpaulin. In this work, a total of 252 working conditions were tested experimentally to study the characteristics of vibrating water in the zone from the center of the table to the water pool boundary, in the conditions of different excitation amplitude, direction, frequency, and water depths. The results show most of the influence and disturbance of the waterproof device is in the horizontal direction. For the case of vertical sinusoidal excitation, water vibration is in the shape of an inverted iron pot in low frequencies (≤ 1 Hz), while it features multiple wave peaks in medium or high frequencies (≥ 3 Hz) with more wave peaks in high frequencies. An increase in the excitation amplitude causes more wave peaks to be gradually superimposed together and amplified, and a collapsing phenomenon will occur when a certain amplitude threshold is exceeded. The amplitude of water vibration peaks shows a downward trend with an increasing water depth. This study demonstrates how to evaluate and improve the model tests on an underwater shaking table.

Key words: underwater shaking table, water-tarpaulin-shaking table interaction, excitation direction, excitation amplitude, excitation frequency, water depth, characteristic of water vibration