Task 7c: Worm tank

Worm tank has a unique shape. In the seismic design of a worm tank, it is desirable to clear the behavior of the worm tank under the seismic loading. We assumed that there are two phenomena in the seismic behavior of the worm tank same as the behavior of the cylindrical and rectangular tanks. One is a sloshing behavior of the water and another is the dynamic response of the worm tank. In this study, we investigate the dynamic characteristics of the worm tank during the strong earthquakes. We conducted the vibration tests to clarify the seismic behaviors of the worm tanks and obtained the valuable data to verify the analytical method. It was found that the natural frequency can be calculated using the eigenvalue formula of the cylindrical and rectangular tanks. Lower modes of the worm tank are identical with that of the rectangular tank. We can estimate the surface behavior and the impact mode using the data of the rectangular tank. (author)