Shake Table Study of Impulsive and Convective Damping Coefficients for Steel Cylindrical Tanks and Comparison with API 650

Dynamic behavior of Tanks under seismic loads is generally nonlinear and has been widely studied by numerous researchers. This was first introduced by Jacobsen and after that, the new method was introduced by Housner for the rigid cylindrical tanks. Fluid vibration induces hydrodynamic pressure on the wall and hence, Housner assumed and classified the seismic response of the rigid tanks into two impulsive and convective components. The Impulsive pressure is caused by the coordinated motions of a fluid part in the tank with the rigid wall of the tank, and the convective pressure is caused by the motion of the other part of the fluid on the tank's free surface. In this paper, a cylindrical steel tankmodel with a diameter of 120 cm, wall height of 125 cmand fluid depths of 60, 80, 100 and 120 cmhas been tested under Tabas, El Centro and Irpinia Earthquakes on the shaking table in the International Institute of Earthquake Engineering and Seismology. The purpose of the experiments was to determine the damping of the impulsive and convective modes of the mentioned tank and to compare the experimental results with the proposed values by API650 Code.