Transient Dynamic Responses of an Integrated Air-Liquid-Elastic Tank Interaction System Subject to Earthquake Excitations

Sloshing problems in partially filled tanks are of increasing concerns in many engineering fields such as marine, chemical, aerospace engineering and automobile industry. The interactive dynamic behaviour of liquid and tank due to their interaction under various loading conditions can have vital impact on the integrity and safe operation of the system. Studies of liquid sloshing and its dynamic effect on the containers are necessary in the early design stage. Currently, most investigations on sloshing problems mainly focus on the analysis of liquids in rigid tanks where the fluid-structure interactions were neglected. Studies on fluid-structure interactions are limited to two phases of liquid-tank interactions. Three phase interactions involving air, liquid and elastic tank are rarely considered. In this paper, the dynamic behaviour of an air-liquid-elastic tank interaction system is investigated. The tank filled with air and liquid is supported at four equally spaced positions around the outer shell. The dynamic pressure in the liquid / air and the displacement in the elastic solid are used as variables to formulate the numerical model incorporating a substructure-subdomain approach and numerical simulations are presented based on a developed computer program. The natural frequencies in association with the corresponding vibration modes and the transient dynamic responses of the complex coupled system subject to earthquake excitations are presented. The ground motion data recorded from El-Centro earthquake is used as an earthquake load to the system. Different interactive cases are examined. These include liquid sloshing in a rigid tank, air-liquid interactions in a rigid tank, liquid-elastic tank interactions and three phase air-liquid-tank interactions. The numerical results obtained reveal the complex coupled behaviour of the system as well as the air effect on dynamic displacement and sloshing pressure. This study provides information for the design of liquid / gas filled tanks in which sloshing behaviour is of interest.