Comparative Study of Design of Over Head Water Tanks for Capacity of 100 kL to 300 kL using Recent Past IS 3370

Abstract

An elevated reservoir is mostly used to store, liquid products like water, petroleum, and other types of chemicals, which require some static head to provide kinetic energy for flow. Except for the durability aspect, design load calculation of various reservoirs is similar regardless of the chemical aggressiveness. In general, water-retaining structures have been designed as crack-free structure to avoid any sort of outflow. As per the observation from the field, the overhead water tanks were designed continuously using the old Indian Standard codes (IS 3370: 1965 (Part 1 to 2), IS 1893: 1984 (Part 1) and IS 875: 1987 (Part 3)). In order to understand the variation in design due to amendments in Indian Standard (IS 3370: 2021 (Part-1 to 2), IS 1893: 2014 (Part-2), IS 875: 2015 (Part-3) in past few years, it is necessary to do comparative study of design of elevated reservoirs for different capacity. This study is an attempt to compare the design provisions based on different design philosophies i.e. WSM (IS: 3370 (1965) and LSM (IS: 3370 (2021). In this paper, variation in reinforcement quantity in different elements of double domed elevated reservoir has been estimated for 100 kL to 300 kL capacity for seismic zone-III and for wind speed 39 m/sec. A design program has been prepared for the design calculations of overhead water tanks using MS excel for different capacity and distinctive IS codal provisions. Comparison of results using different design philosophies has raised the need for retrofitting of various elements of existing water tanks.