Seismic Response of RC Elevated Liquid Storage Tanks Using Semi-active Magneto-rheological Dampers

Abstract

AbstractThe paper presents the use of semi-active magneto-rheological (MR) dampers for the structural response reduction of the reinforced concrete (RC) elevated liquid storage tanks. The effectiveness of MR dampers is investigated based on the control strategies and the placement of the dampers in the staging. The RC elevated liquid storage tank is modeled as a multi-degree freedom system for the staging with a two-mass model for the container with liquid. Two control systems, viz., open-loop and closed-loop control systems are considered. The control algorithms employed are (1) Passive-OFF, (2) Passive-ON, (3) Clipped-Optimal Control (COC), and (4) Simple Semi-active Control (SSC). The study is also focused on the effect of change of voltage on the response quantities. For the COC algorithm, the feedback gain is obtained by considering velocity feedback. The present study proposes a SSC algorithm which is an effective way of controlling the response of RC elevated tank, which uses the ratio of the damper force and capacity of the damper. For numerical simulation, a code is developed in MATLAB. The coupled differential equations of motion for the system are solved using the state-space method. The response of the broad and slender tanks is studied by taking the ratio of the height of the liquid to the radius of the container (S) as 0.5 and 2.0, respectively. The controlled response of the tank under eight different ground motions comprising of near-field and far-field components of earthquakes is evaluated and compared with that of the uncontrolled response. Base shear, displacement, and damper force are obtained. The results showed that the structural response is effectively controlled using semi-active MR dampers with the proposed SSC strategy. The simple semi-active control algorithm proposed in this study could be considered as a proficient algorithm for the seismic response reduction of RC elevated liquid storage tanks using SAMRD.KeywordsRC elevated liquid storage tankSemi-active magneto-rheological damper (MR)Semi-active control algorithmsOptimal linear controlOpen-loop controlClosed-loop control