Abstract
Liquid‐filled tanks are effective storage infrastructure for water, oil, and liquefied natural gas (LNG). Many such large‐scale tanks are located in regions with high seismicity. Therefore, very frequently base isolation technology has to be adopted to reduce the dynamic distress of storage tanks, preventing the structure from typical modes of failure, such as elephant‐foot buckling, diamond‐shaped buckling, and roof damage caused by liquid sloshing. The cost‐effective seismic design of base‐isolated liquid storage tanks can be achieved by adopting performance‐based design (PBD) principles. In this work, the focus is given on sliding‐based systems, namely, single friction pendulum bearings (SFPBs), triple friction pendulum bearings (TFPBs), and mainly on the recently developed quintuple friction pendulum bearings (QFPBs). More specifically, the study is focused on the fragility analysis of tanks isolated by sliding‐bearings, emphasizing on isolators’ displacements due to near‐fault earthquakes. In addition, a surrogate model has been developed for simulating the dynamic response of the superstructure (tank and liquid content) to achieve an optimal balance between computational efficiency and accuracy.
Highlights
Base-isolation technology is considered as an efficient approach to reduce the seismic vulnerability of liquid storage tanks. e fundamental concept of base-isolation is the “decoupling” of structure from ground motions by installing isolators, i.e., devices with low horizontal and high vertical stiffness to accommodate the vertical loads of the structure
Time-histories derived from natural and simulated records are included in this suite of accelerograms. e use of a sufficient number of properly selected excitations in conjunction with a huge number of multiple-stripe dynamic analysis (MSDA)/Incremental dynamic analysis (IDA) analyses is imperative in order to achieve reliable fragility analysis results. e specific suite of acceleration time-histories consists such a case, since it is a well-established set of impulsive ground motions, with epicentral distances less than 10 km and very high peak ground acceleration (PGA) recorded values ranging from 0.45 g to 1.07 g, which is usually used in fragility analysis studies [43]
The displacement capacity of single friction pendulum bearings (SFPBs) and of the different pendulum mechanisms of triple friction pendulum bearings (TFPBs) and quintuple friction pendulum bearings (QFPBs) were associated to three performance-based design (PBD) levels (SLE, design basis earthquake (DBE), and maximum considered earthquake (MCE)) by performing repeated dynamic nonlinear analyses
Summary
Base-isolation technology is considered as an efficient approach to reduce the seismic vulnerability of liquid storage tanks. e fundamental concept of base-isolation is the “decoupling” of structure from ground motions by installing isolators, i.e., devices with low horizontal and high vertical stiffness to accommodate the vertical loads of the structure. Wang et al [10] studied the effectiveness of SFPBs installed at the base of cylindrical tanks using a hybrid structure-hydrodynamic numerical model. Parameters such as tank aspect ratio, friction coefficient of SFPBs and earthquake intensity were examined. Using a similar simplified model of the masses, Panchal and Jangid [12] investigated the seismic response of liquid storage tanks isolated with variable friction pendulum system (VFPS). Seleemah and El-Sharkawy [15] investigated the dynamic response of elevated squat and slender liquid storage tanks isolated by elastomeric and sliding bearings (SFPB)
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