ANALYSIS ON VERTICAL TANK FLUID-SOLID COUPLING VIBRATION AND BASE ISOLATION DYNAMIC RESPONSE

The response of liquid storage tank to seismic excitation is manifested as the coupling motion between the flexible tank and fluid, due to the complexity of the problem, the design code for the tank is mainly based on the one-dimensional simplified spring mass model of Haroun-Housner to study linear seismic response. But this method can evaluate the seismic performance of the tank only from the aspect of structural linear overall response, it hasn't taken into account the factors such as nonlinear geometric and material effects, variable thickness of the tank wall and etc. This paper adopted the large-scale general-purpose finite element software ANSYS and built the fluid-solid coupling basic isolation system model, using the New mark- beta method to figure out the nonlinear dynamic equations of the isolation tank, it systematically explores the effects of the isolation parameters on the seismic response of the isolation tank in third site with the seismic fortification intensity of 9 degree. It provides reference data for the shock absorption analysis and design of fluid-solid coupling tank. Results indicate that the base frequency of the isolation bearing is the most important parameter which affected the shock absorption performance of the tank. The most appropriate base frequency of vertical tank control system is between 3rad/s and 4rad/s, the optimum damping ratio is between 0.2 and 0.4, therefore the optimal parameter should be chosen for the isolation design of tanks with different height-diameter ratios.