Investigation of the feasibility of prestressed concrete (PC) over conventional reinforced concrete (RC) in water retaining structures

Abstract

Concrete water tanks are used to store and supply safe drinking water and are designed as crack-free structures. The demand for water tanks will continue to increase in the coming years; quick construction methods and economical design approaches will be helpful in the selection of water tanks for relevant applications. Prestressed Concrete (PC) will be a better alternative for Reinforced Concrete (RC) water tanks which are commonly used in Sri Lanka. This paper presents design guidance for PC circular water tanks resting on the ground. The design and construction approaches for PC circular water tanks were identified following EN 1992-1-1:2004 and EN 1992-3:2006 standards. The Midas FEA Finite Element (FE) software was used to analyse the tanks. The economic feasibility of both PC and RC tanks is compared for different tank capacities. The design outputs were converted into structural drawings and bills of quantities. Results of the material take-offs showed that RC is economical only for 4500m 3 or less capacity. For higher capacities (above 4500 m3), PC tanks become cheaper by around 12-14%. The information presented in this paper will therefore be helpful to understand the design philosophy for the safe and economical design of water tanks with better crack control.