مهندسی عمران شریف (Feb 2020)
SEISMIC ANALYSIS OF BASE-ISOLATED WATER STORAGE TANKS SUBJECTED TO LONG-PERIOD EARTHQUAKES USING CRITICAL EXCITATION METHOD
Abstract
In this paper, the seismic behavior of base-isolated water storage tanks under the effect of long-period earthquakes has been investigated; as relatively high period of these types of structures causes them to be sensitive against long-period earthquakes. In this regard, an efficient and new method called critical excitation method (CEM), is employed for seismic behavior of base-isolated water storage tanks, for the first time. In the CEM, it is tried to produce critical earthquakes for each structure based on its characteristics and parameters, and then apply them to the undertaken structure so that the seismic behavior of structures during and after the earthquake may be increased. To investigate behavior of base-isolated water storage tanks under long-period earthquakes, three types of broad, middle and slender storage tanks have been used, for which two types of isolators (i.e., lead rubber bearing (LRB) and friction pendulum system (FPS)) are equipped. In order to model seismic behavior of water storage tanks considering fluid-structure dynamic interaction effects, a simplified and practical model proposed by Haroun has been employed in this research. The base-isolated water storage tanks have been exposed to long-period earthquakes to magnify responses. In addition, in order to develop the CEM, it has been used to analyze base-isolated water storage tanks through modifying available matrices in the equation of motion, rewriting the required formulas and developing the necessary codes in MATLAB environment. According to the results obtained from this research for the specific cases considered, it was found that using energy dissipation systems has caused these structures to perform better. Moreover, by proposing the CEM, this method was investigated for the first time with regard to base-isolated water storage tanks. In addition to introducing the critical parameters of this method, it was found that using this method leads to critical conditions in base-isolated water storage tanks.
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