Influence of Tank Geometry on Seismic Performance and Cost of RCC Overhead Water Tanks in Indian Seismic Zones

Overhead water tanks made of reinforced cement concrete (RCC) are critical to municipal infrastructure and are at great risk for seismic forces because of their elevated heights and the large mass of the liquid. This study offers a zone-wise comparative design and economic analysis of three common tank shapes, a circular, rectangular, and Intze configured to hold 500 kL. Each tank shape was modelled and analyzed in Staad.Pro, and the resulting seismic performance was assessed using the Response Spectrum Method based on IS 1893 (Part 2): 2014 in all Indian Seismic Zones II, III, IV, and V. The parameters of interest were the base shear, top displacement, material quantities of concrete and steel, and total cost of construction. The results showed that circular tanks performed best in reduced seismic loads in Zone II originations with loads symmetrically dispersed along both axes, while Intze tanks performed best in Zones IV-V, showing reduced displacement and cost, along with limits of horizontal force. Rectangular tanks showed a tendency for poorer earthquake performance and more material use, but are common due to site constraints in urban areas. The conclusions indicate the utility of a geometrically based design method whereby an Intze tank can be built in Zones IV-V, while Circular tanks provide adequate seismic safety and economy in Zones II-III. Recommendations are provided for future development of earthquake-resistant water infrastructure, and its advantages for municipalities in India.