Effect of local geometrical imperfection on dynamic buckling of cylindrical storage tanks

Steel cylindrical tanks are the most susceptible to damage due to dynamic buckling during earthquakes. The production of cylindrical shell without imperfections is very difficult or sometime even impossible. The most previous research to study the geometrical imperfection in the shell of steel tanks using various methods did not deal with the fluid–structure interaction (FSI) and the dynamic loads. In this paper, the FSI numerical model is used to estimate the effect of local geometrical imperfection with dynamic buckling of fluid-filled tanks. The liquid inside the tank was modeled using specific Ansys’s finite elements and fluid–structure interaction. The calculation includes modal and time history analysis, including material and geometric nonlinearity. Then a typical cylindrical tank is analyzed by the application of three different stability criteria to estimate the critical PGA. The obtained dynamic buckling results of the perfect and imperfect tank are compared. The effect of geometrical imperfection on dynamic buckling is clearly shown. The PGAcr of the imperfect tank models decreases by 09.11%.