Study on vertical sloshing load acting on roof of cylindrical tanks under seismic wave excitation

池末 俊一*; 岩崎 晃久*; 佐郷 ひろみ*; 横井 忍*; 山本 智彦  

Ikesue, Shunichi*; Iwasaki, Akihisa*; Sago, Hiromi*; Yokoi, Shinobu*; Yamamoto, Tomohiko

During an earthquake, sloshing occurs in a cylindrical tank when a frequency component close to the natural frequency of sloshing is included in the seismic wave. When high amplitude sloshing occurs, the free liquid surface level fluctuates greatly in the tank, and the liquid surface collides with the roof of the tank. In tank design, it is important to evaluate the sloshing load acting on the roof. In this study, we extended this method to deal with seismic wave excitation. In seismic wave excitation, the tank is excited by irregular wave, and the phenomenon of sloshing becomes more complicated than sinusoidal excitation. To simplify this complicated phenomenon, we proposed a concept of equivalent growth wave number. This number represents the magnitude of the increase in the peak of liquid surface level, during seismic wave excitation. We proposed a method to quantitatively evaluate this number from seismic response analysis. In addition, we proposed a method to evaluate the vertical load on the roof during seismic wave excitation, by introducing this number into the predictive evaluation method.