Study Of The Seismic Response Of R/c IsolatedElevated Water Tanks

This investigation assesses the seismic response of parametric elastic models of reinforced concrete isolated elevated water tanks. From the study of the physical and geometric variables that characterize elevated water tanks, it was possible to define parametric models with the purpose of obtaining a widely representative family of structures. The parameters were grouped in the following form: a) elevated tank: ratio of heights, ratio of slenderness, ratio of diameters, ratio of diameter to thickness, and ratio of water mass to structure mass, b) isolation system: ratio of slenderness, horizontal and vertical stiffness, c) water: the waterstructure interaction effect is modeled using the mechanical analogy proposed by Housner. This special type of continuous structure, similar to an inverted pendulum, has been discretized according to the lumped mass criterion and the support structure of the tower was partitioned in ten one-dimensional elements. As seismic loads were applied, the design spectrum of accelerations was used as recommended by the Chilean code NCh 2745 Of.2003. The maximum responses were obtained for the lateral displacements, the shear forces and bending moments. The sensitivity analysis of the structural models of isolated elevated water tanks allowed us to observe that the maximum bending moments and the maximum shear forces are equivalent to one eighth of the maximum responses obtained for a similar fixed-base elevated water tank, and that the relative lateral displacements are lower than 0.2‰, reducing the deformations in the structure significantly.