SEISMIC DESIGN RECOMMENDATIONS FOR ELEVATED WATER TANKS

Abstract

Elevated water tanks are critical components of any urban planning scheme as they are commonly adopted by the municipal corporations to store the necessary water to meet the city's water demand. Experiences from past earthquakes have shown a strong indication that most of these structures are susceptible to damages related to earthquakes. One of the prime concerns for structural designers is the sloshing effects of the water stored in the tank. The liquid sloshing may cause huge loss of human life, economic and environmental resources due to unpredicted failure of the container. Sloshing basically refers to the movement of water contained in the overhead tank when subject to lateral motions occurring due to wind forces or earthquake excitations. In this thesis, special consideration has been given to the effects of sloshing during the design of elevated water tanks. It is already established that elevated water tanks possess low ductility and energy absorbing capacity when compared to the conventional buildings. In view of this, most of the design codes around the world suggest a higher design seismic force for the design of such elevated water tanks. This paper focuses on the seismic codal provisions laid down in six different codes including IBC 2000, ACI, AWWA, API, Eurocode 8 and NZSEE and comparing them to the provisions laid down in Indian design codes. Based on the results of this study, various similarities and limitations were found in the codal provisions which are listed in brief.