Experimental Study on Coupling between Beam-Type and Oval-Type Vibrations of a Cylindrical Water Storage Tank

In this study, a vibration experiment with a reduced scale model of a large-size cylindrical water storage tank is performed in order to investigate the nonlinear vibration responses of the cylindrical tank when the beam-type and the oval-type vibrations are coupled. The sinusoidal sweep test is conducted by varying the input acceleration from smaller to larger input. As a result, the resonance frequency shifts to the lower frequency region and the response magnification factor becomes smaller as the input acceleration level becomes larger. Furthermore, when larger input is applied, the oval-type vibration has a subharmonic resonance of order one-half, and its displacement-amplitude grows up significantly. It can be assumed that the large amplitude of oval-type vibration generates a geometrical nonlinearity for the beam-type vibration.