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Earthquakes and Structures
  Volume 16, Number 5, May 2019, pages 523-532

Seismic protection of LNG tanks with reliability based optimally designed combined rubber isolator and friction damper
Ali Khansefid, Ali Maghsoudi-Barmi and Alireza Khaloo

    Different types of gas reservoir such as Liquid Natural Gas (LNG) are among the strategic infrastructures, and have great importance for any government or their private owners. To keep the tank and its contents safe during earthquakes especially if the contents are of hazardous or flammable materials; using seismic protection systems such as base isolator can be considered as an effective solution. However, the major deficiency of this system can be the large deformation in the isolation level which may lead to the failure of bearing system. In this paper, as a solution, the efficacy of an optimally designed combined vibration control system, the combined laminated rubber isolator and rotational friction damper, is investigated to evaluate the enhancement of an existing metal tank response under both far- and near-field earthquakes. Responses like impulsive and convective accelerations, base shear, and sloshing height are studied herein. The probabilistic framework is used to consider the uncertainties in the structural modeling, as well as record-to-record variability. Due to the high calculation cost of probabilistic methods, a simplified structural model is used. By using theMont-Carlo simulation approach, it is revealed that this combined isolation system is a highly reliable system which provides considerable enhancement in the performance of reservoir, not only leads to the reduction of probability of catastrophic failure of the tank but also decrease the reservoir damage during the earthquake.Moreover, the relative displacement of the isolation level is controlled very well by this combined system.
Key Words
    combined isolation system; rotational friction damper; rubber; optimization; probabilistic framework; LNG tank
Ali Khansefid, Ali Maghsoudi-Barmi and Alireza Khaloo: Civil Engineering Department, Sharif University of Technology, Azadi Ave., Tehran, Iran

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