SEISMIC ANALYSIS OF CONCRETE RECTANGULAR CONTAINERS ISOLATED BY DIFFERENT ISOLATION SYSTEMS

The liquid storage containers are one of the most important structures of the lifeline and industrials facilities in all over the world. These structures can be used as grounded, pneumatic and embedded containers. The grounded concrete tanks are widely used for the long-term storage of nuclear spent fuel assemblies. Hence, protection of these structures against severe seismic events has become crucial. Numerous studies have been done for the seismic analysis of fluid containers. Most of them are concerned with cylindrical or rectangular tanks with fixed-base. This paper focuses on analyzing the results of seismic responses of flexible rectangular tanks isolated by three types of outstanding isolation systems. The considered systems are high damping rubber-bearing (HDRB), lead-rubber bearing (LRB) and friction pendulum bearing (FPB). An equivalent mechanical model of rectangular tanks is used in this study which contains three lumped masses known as: convective mass, flexible mass and rigid mass. Eventually, the seismic isolation systems are found to be very effective in reducing the base shear and hydrodynamic pressures but usage of this technology found to have adverse or/and neutral effects on the sloshing height. An increase in displacements for all isolation systems in horizontally isolated tanks seems to be inevitable.