BEHAVIOUR OF ELEVATED WATER TANK UNDER SLOSHING EFFECT

Abstract

Liquid storage tanks are considered essential lifeline structures. Water tanks, in particular , are important to the continued operation of water distribution system in event of earthquakes. Most of the failures of large tanks after earthquakes are suspected to have resulted from the dynamic buckling caused by overturning moments of seismically induced liquid inertia and surface slosh waves. Recent earthquakes have shown that liquid storage tanks are found to be vulnerable to damage. Current knowledge about the behaviour of liquid storage tank is extensive, but many of the analytical and theoretical results are for tanks without roof systems and include number of simplifying assumptions like small deformation and linear elastic material property. The nonlinear wave approach was not attempted at initial stage, in predicting the seismic response of tank structures because of its mathematical difficulties determining the elevation of the unknown moving free surface and in evaluating the geometrically non-linear boundary conditions on the liquid surface. It is noted that under nonlinear conditions, sloshing heights are larger than those calculated under linear condition. In the present study sloshing effect in elevated water tank is studied by using Finite Element Method (FEM) based computer code. Various parameters have been considered such as height of container, depth of water in tank (30%, 50%, 70% and full) and height of staging etc.