The effect of earthquake site-source distance on dynamic response of concrete elevated water tanks

Elevated water tanks are one of the essential components of water supply networks that are expected to remain functional after severe earthquakes. In this paper, the effect of earthquake site-source distance on the dynamic response of reinforced concrete elevated water tanks with shaft type support is investigated. Six different pairs of near and far-field earthquake records each consisting of horizontal and vertical components are selected for the dynamic analyses. A two-dimensional structural system is numerically simulated using finite element method. The fluid-structure interaction is taken into account using single mass and two-mass analogies. This method is capable of considering both impulsive and convective responses of fluid-tank systems. The structure is assumed to be fixed at the base. Comparisons are made on base shear, base moment and sloshing responses under different near and far-field ground motions and simultaneous effects of their horizontal and vertical components. The results are verified and compared with those obtained from current code provisions. It is concluded that the dynamic behavior of the system is highly sensitive to site-source distance of the earthquake records. Moreover, two different simplified methods for modeling of fluid-structure interaction are studied and compared considering various dynamic responses.