Assessment of equivalent cylinder method and development of charts for analysis of concrete conical tanks

Elevated conical tanks are widely used as water reservoirs in various locations around the globe. The vessel of a conical tank can consist of a truncated cone solely or a truncated cone with a top cylindrical part. Current codes of practice do not provide any provisions or guidelines for designing reinforced concrete conical tanks under hydrostatic loading. Available provisions are limited only to cylindrical and rectangular tanks. In this paper, a nonlinear Finite Element Model (FEM), based on shell element discretization, is used to analyze hydrostatically loaded reinforced concrete conical tanks. A common simplified approach used in the design of conical tanks involves replacing the conical vessels with equivalent cylinders. The adequacy of this simplified method is assessed in this study through comparison with the detailed finite element results. The FEM is then used to develop a set of charts which can be used to determine the adequate thickness as well as straining actions that develop in a liquid filled reinforced concrete conical tank. The use of this set of charts in designing reinforced concrete conical tanks is illustrated through worked examples.