STUDY OF SEISMIC RESPONSE OF RECTANGULAR WATER TANK

Abstract

Water tanks are very important structures and consist of various types. Such tanks become vital structures after a seismic activity for providing potable water supply and in controlling earthquake generated fires. Elevated tanks get heavily damaged or even collapse during earthquakes. Tanks are also utilized to store various types of products, for example petroleum supplies in cities and industrial areas. Damages to these structures during high seismic activities may lead to many hazardous events. Therefore storage tanks should stay functional during and after earthquakes. Seismic behavior of storage tanks including movement of stored liquid has attracted attention of many researchers. Their dynamic behavior has been found to be different in comparison to other structures. The seismic behavior of storage tank is affected by various factors like soil-structure interaction, structural parameters, earthquake characteristics, the supporting system etc. Experiences show that inadequately designed or detailed liquid storage tanks, which are common structures in various facilities, suffered extensive damage during past earthquakes. Therefore, the satisfactory seismic response study of such structures is very important. The purpose of this project is to study and computationally examine the effects of earthquake frequencies on the seismic behavior of rectangular storage tanks. Phenomenon of sloshing of liquid in rectangular water tanks has been studied with and without baffles. Wooden baffles of different heights were used to affect sloshing with variation of initial liquid fill level relative to the baffle height. The tank is excited with frequencies near to natural frequencies of the liquid in the tank at different modes. It can be observed that if the tank is subjected to seismic excitations at resonant excitation frequencies, liquid sloshing becomes extreme and wall forces are intensified. It is observed that baffles may affect sloshing of stored liquid inside tanks to a great extent. The maximum impact pressure for the tank with baffle is seen to be significantly reduced in comparison to a tank without any baffle.