EFFECT OF ISOLATOR ON SEISMIC BEHAVIOR OF ELEVATED WATER TANK

Considering the vulnerabilities of elevated water tanks, as the most important and necessary potent water supply structures in cities, during the previous earthquakes, the need to maintain their operability after earthquake is of great importance. Design of seismic isolators and their application in specific structures, including elevated air tanks, is one of the innovative technologies in the field of structural and earthquake engineering. Installed at the building foundation, at different floors, or under bridge decks, this system can provide damping and depreciate lateral forces in order to decline their adverse effects. In fact, by adding this system to different structures, we can decrease the energy exerted on the structures as a result of earthquake. Therefore, by reducing demands, we can prevent damages to structural elements, development of plastic hinges, and finally failure of structural elements. In tank structures, bulk of the mass is placed at a considerable distance from the foundation. Analysis of these structures under the lateral forces exerted on them is of great importance, especially for securing these structures and maintaining their efficiency. Using time history dynamic analysis and taking into account the effect of interaction between fluid and structure, a concrete-foundation elevated water tank both with and without seismic isolators is analyzed at different water levels and earthquake acceleration records. In this model, the seismic isolator was used in the junction of tank and concrete columns. The results show that application of isolators in elevated concrete tanks will damp the adverse earthquake energies. The damping process increases the natural period of structure and significantly decreases the extent and acceleration of forces exerted on the building. An increase in natural period of the structure will in turn decrease the tank displacements base and shear forces in the tank, which will lead to the stability of the structure both during and after earthquake and will maintain the post-earthquake operability of the tanks that is the final goal of the present study.