Seismic analysis of baffled liquid storage tanks using boundary element method

Nowadays, fluid storage tanks are as important as fluids in urban life. The dynamic behavior of this important structure is different from common structures. Baffles as a passive control device can reduce the effects of sloshing which reduces the structural response to seismic excitation. In this study, the effect of baffles on seismic response of cylindrical vertical liquid storage tanks is investigated. The considered baffle is an annular plate with constant level from the base and constant inner diameter fixed on wall of the tank. Considering Laplace equation as the governing equation of fluid domain, and using boundary element method, a rigid tank is analyzed in the frequency and time domains. Afterwards, the baffle effects on natural frequency (in the frequency domain), and on base shear and overturning moment (in the time domain) due to El Centro and Erzincan earthquakes are investigated. Based on the results of mentioned analyses, it is observed that when the baffle is installed, the natural frequency of liquid domain reduces. Moreover, by installing the baffle, the base shear slightly increases whereas overturning moment remarkably reduces.