Seismic response of elevated RC tanks equipped with the seesaw system

Abstract

This paper investigates the effectiveness of the seesaw system when applied to elevated tanks in order to mitigate their seismic response to strong seismic motions. In particular, non-linear time-history analyses (NLTH) are conducted on an elevated steel frame reinforced concrete tank (RC), equipped with the seesaw system. Both the horizontal and vertical components of a set of seismic motions are used for the NLTH analysis, whereas two cases of water height within the RC tank are assumed. A rigid or flexible foundation of the RC tank is considered in order to assess the effects of soil-structure interaction (SSI). The seismic response indices monitored are the drift ratio and the residual drift ratio of the tank, the maximum moments of the tank wall, the maximum force of the members of the seesaw system and the exhibition of plastic hinges to the ends of the columns of the steel frame. From the results obtained it is concluded that a properly detailed seesaw system can be a good solution in improving the seismic behavior of elevated RC tanks.