Parametric study on dynamic behavior of cylindrical ground-supported tanks

In this paper, the dynamic behavior of cylindrical open top ground-supported water tanks is investigated. The main focus of this study is to identify the major parameters affecting the dynamic response of such structures and to address the interaction between these parameters. Examined parameters include sloshing of liquid free surface, tank wall flexibility, vertical ground acceleration, tank aspect ratio, and base fixity. In addition, the dynamic results obtained from the rigorous finite element (FE) method are compared with those recommended by current practice and thereby the adequacy of current code provisions in estimating the dynamic response of liquid-filled cylindrical containers is investigated. The validity of the proposed FE method is verified by comparing the results with those calculated from well-proved analytical methods available in the literature. Both time history and free vibration analyses are carried out on concrete tank models with different aspect ratios. Time history response of both rigid and flexible tanks having different conditions at the base; fixed and hinged under both horizontal and vertical components of earthquake is obtained using the direct integration method. Based on the computed results, recommendations on seismic design of cylindrical liquid containers are made. It is concluded that the current design procedure in estimating the hydrodynamic pressure is too conservative.