Improving seismic performance of elevated cylindrical water storage tanks using nonlinear isolators incorporating liquid–structure interaction

Pervasive construction of elevated liquid tanks as the most important sources for urban hygienic water, and their failure under earthquake, highlighs the necessity for research toward new passive control devices. Design and use of base-isolation systems for elevated liquid tanks is propounded as a novel seismic engineering technology. To date, no special examination has been discussed in relation with the workability of such systems in reducing the seismic response of elevated liquid tanks considering tank wall flexibility. In this study, the seismic performance of a steel elevated water tank with/without isolator was analyzed and outcomes were evaluated using lead-rubber and elastomeric bearings by performing time-history analyses. To this end, finite shell elements for tank wall and internal finite elements for liquid, and bilinear hysteretic elements for the base-isolation systems are elected, and the seismic analysis of flexible liquid tank is performed in the time domain under real earthquake. The results show that the lateral control device despite excessive structural displacement could offer a substantial benefit for reducing the system’s seismic response which depends on the earthquake characterestics.