International Conference on Advances in Civil and Mechanical Engineering Systems, 23-24 Dec.2014 Government College of Engineering, Amravati in association with SVNIT, Surat, India http://acmes2014.in 355 Effect of Staging Height on Seismic Performance of RC Elevated Water Tank Dr. Suchita Hirde 1 , Mr. Umesh L. Raygandhi-Shaha 2 1 Professor in Applied Mechanics Dept., Govt. College of Engineering, Karad, 415124, Dist. Satara (M.S). 2 Student M.E. Structural Engineering, Dept. of Applied Mechanics, Govt. College of Engineering, Karad, PIN 415124, Dist. Satara (M.S). Email Id: hirde.suchita@gmail.com , umesh.r111@gmail.com Abstract: Water is as important commodity as food and air for the existence of life. The overhead tanks which have been the inevitable part of water supply system are important public utility structures and industrial structure by the help of which the required water head can easily be achieved and water can be made available to all by the mere action of gravity. As known from very upsetting experiences, elevated water tanks were heavily damages or collapsed during earthquake. This was might be due to the lack of knowledge regarding the proper behavior of supporting system of the tank against dynamic effect and also due to improper geometrical selection of staging patterns. Due to the fluid-structure interactions, the seismic behavior of elevated tanks has the characteristics of complex phenomena. So there is necessity to understand the behavior of elevated water tanks supported on different types of staging under earthquake forces. For elevated water tank, shaft type staging and framed type of staging are normally used. In this study, an effort has been made to study the effect of staging height on seismic behavior of elevated water tank supported on frame type staging with consideration and modeling of impulsive and convective water masses inside the container for different zones and soil types. This study will be useful to the civil engineers to understand the seismic behavior of elevated water tanks supported on framed type staging situated in various earthquake zones. Keywords: Elevated water tank, Frame type staging, Seismic analysis, Staging height Conference Stream: Civil Engineering. 1. Introduction: Water is human basic needs for daily life. Sufficient water distribution depends on design of a water tank in certain area. An elevated water tank is a large water storage container constructed for the purpose of holding water supply at certain height to pressurization the water distribution system. Thus Water tanks are very important for public utility and for industrial structure. Elevated water tanks consist of huge water mass at the top of a slender staging which are most critical consideration for the failure of the tank during earthquakes. Elevated water tanks are critical and strategic structures and damage of these structures during earthquakes effects on drinking water supply, cause to fail in preventing large fires and substantial economic loss. Since, the elevated tanks are frequently used in seismic active regions, seismic behavior of these tanks has to be investigated in detail. Due to the lack of Knowledge of supporting system some of the water tank were collapsed or heavily damages. Hence in this study, an effort has been made to study the seismic behavior of elevated water tank with consideration and modeling of impulsive and convective water masses inside the container for different zones and soil types. 2. Modeling and analysis of elevated water tank for earthquake: 2.1 Model provision: Two mass model for elevated tank was proposed by Housner (1963) [1] which is more appropriate and is being commonly used in most of the international codes including Draft code for IS 1893 (Part-II). The pressure generated within the fluid due to the dynamic motion of the tank can be separated into impulsive and convective parts. When a tank containing liquid with a free surface is subjected to horizontal earthquake ground motion, tank wall and liquid are subjected to horizontal acceleration. The liquid in the lower region of tank behaves like a mass that is rigidly connected to tank wall. This mass is termed as impulsive liquid mass which accelerates along with the wall and induces impulsive hydrodynamic pressure on tank wall and similarly on base Liquid mass in the upper region of tank undergoes sloshing motion. This mass is termed as convective liquid mass and it exerts convective hydrodynamic pressure on tank wall and base. For representing these two masses and in order to include the effect of their hydrodynamic pressure in analysis, spring mass model is adopted for ground-supported tanks and two-mass model for elevated tanks.