Simplified earthquake response analysis of rectangular liquid storage tanks considering fluid-structure interactions

A simplified model of a rectangular liquid storage tank is proposed to estimate the earthquake responses of the system while considering the effects of fluid-structure interactions. The complicated three-dimensional structural behavior of a rectangular tank is represented by the simple combination of the fundamental modes of a rectangular-ring-shaped frame structure and a cantilever beam. The governing equation for the system is derived from Lagrange's equation. The earthquake responses of deflection, hydrodynamic pressure and its resultant force and moment, base shear and overturning moment due to the structural deformation are obtained from the solution of the governing equation. The effective masses of the system and their heights are presented with the effective added masses and their heights from the hydrodynamic effects. The total earthquake responses are obtained with the convective earthquake responses taken into consideration. The proposed simplified model is applied to example rectangular liquid storage tanks with various aspect ratios, and the accuracy of the model is demonstrated. The proposed simplified model can be employed for the seismic design of a rectangular liquid storage tank, and reliable estimations for earthquake responses of the considered fluid-structure interaction system are obtained without sophisticated and/or complicated dynamic analysis.

Automated summary

A simplified model is proposed to estimate the earthquake responses of a rectangular liquid storage tank considering the fluid-structure interactions. The complex three-dimensional structural behavior of the tank is represented by a combination of fundamental modes of a rectangular-ring-shaped frame structure and a cantilever beam. The system's governing equation is derived, and earthquake responses such as deflection, hydrodynamic pressure, base shear, and overturning moment are obtained from the solution.