SEISMIC ANALYSIS OF SHAFT SUPPORTED ELEVATED TANKS.

The analysis of shaft-supported elevated water tanks subject to seismic forces is presented for five tanks of different capacities. The Indian Code recommends that elevated tanks may be considered as systems with a single degree of freedom with their mass concentrated at their centers of gravity. In this study, tanks have been analyzed as multi-degree-of-freedom systems and the percentage of error involved in considering the systems with a single degree of freedom is presented. The variation in this error with respect to the height of the water tank, the number of degrees of freedom and the capacity of the tank is also presented.