Effect of Earthquake Characteristics on Seismic Performance of RC Elevated Water Tanks Considering Fluid Level within the Vessels

Abstract

The dynamic behavior of a liquid storage tank as a special structure differs from that of general structures. Important structures of cylindrical shape are used to store vital products, such as water and petroleum products, for cities and industrial facilities. Damage to these structures during a strong ground motion may lead to fire or other hazardous events. Liquid storage tanks are lifeline structures and strategically very important, since they have vital use in industries and nuclear power plants. In this research, an example reinforced concrete (RC) elevated water tank, with 900 cubic meters capacity, is studied under three pairs of earthquake records and analyzed in time history by using mechanical and finite element modeling techniques. The liquid mass of the tank is modeled as lumped masses known as sloshing mass, impulsive mass and rigid mass. The corresponding stiffness constants associated with these lumped masses are worked out depending upon the properties of the tank wall and liquid mass. Tank responses including base shear, overturning moment, tank displacement, and sloshing displacement under these three pairs of earthquake records are calculated, and then the results are compared and contrasted. Results show that the system responses are highly influenced by the structural parameters and the earthquake characteristics, such as frequency content.