Study of water towers

Abstract

At present, there is little published literature for estimating the requirements of material, and cost of construction of elevated water tanks. The author has carried out a detailed analysis of costs and the requirements for material for elevated water tanks of various capacities, staging height, bearing capacities of soil and lateral forces due to wind. This author has taken an opportunity to design elevated tanks of Intze, Conical and Cylindrical with the designer's requirements, such as capacity, dimensions, bearing capacity of soil, wind force, option of tank full or empty condition, and reinforcement details. The bar schedule details are also presented by this author. That particular designer's requirement is fulfilled and the cost is estimated with the present rate of materials and form works. The findings of this study are useful in the design process for deciding upon the cost optimization for the three types of elevated towers. On the one hand, for optimization of intze tower the horizontal angle of conical shell to be maintained between 40 degree and 50 degree. On the other hand, the cylindrical tower is the least costly tower at less than 400 m' capacities while the intze tower is least costly at more than 400 m3 capacities. Although these comparisons are based on the condition of supporting structure height = 15 m, basic wind speed = 38 mis, soil bearing capacity = 150 kN/m2 and the National Water Supply and Drainage Board 'Rate book - 2007' prices. In general for intze tanks, the cost for foundation is between 13% and 20%, supporting structure is between 10% and 26% and tank is between 55% and 75%. But for cylindrical tanks, the cost for foundation is between 15% and 21%, supporting structure is between 16% and 29% and tank is between 53% and 65%. In view of material cost, steel has the greatest effect on tank and supporting structure while concrete has the greatest effect on foundation. For proper planning and execution of a project, accurate estimates of the cost and requirements for materials for water towers are essential.