The effects of input earthquake characteristics on the nonlinear dynamic behavior of FPS isolated liquid storage tanks

2016 ◽  
Vol 24 (7) ◽  
pp. 1264-1282 ◽  
Author(s):  
Saman Bagheri ◽  
Mostafa Farajian
Keyword(s):  
Passive Control ◽  
Base Isolation ◽  
Ground Motions ◽  
Storage Tanks ◽  
Ground Acceleration ◽  
Pendulum System ◽  
Aspect Ratios ◽  
Liquid Storage ◽  
Isolation Systems ◽  
Friction Pendulum

There are several methods to reduce the seismic damages in liquid storage tanks. One of these methods is to use passive control devices, in particular seismic base isolators. Among the different base isolation systems, the Friction Pendulum System (FPS) whose period does not depend on the weight of the system is more appropriate for isolation of liquid storage tanks. The aim of this paper is to investigate the effects of peak ground acceleration (PGA) and pulselike characteristics of earthquakes on the seismic behavior of steel liquid storage tanks base isolated by FPS bearings. In addition, impact effects of the slider with the side retainer are investigated, as well as effects of tank aspect ratio, isolation period and friction coefficient. The obtained results of tanks with different aspect ratios indicate that the responses get more reduced due to isolation under far-field ground motions compared to near-fault ground motions. It is also seen that the response of a base isolated tank is affected when contact takes place with the side retainer of the FPS.

scholarly journals Seismic Vulnerability Assessment of Liquid Storage Tanks Isolated by Sliding-Based Systems

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Alexandros Tsipianitis ◽  
Yiannis Tsompanakis
Keyword(s):  
Large Scale ◽  
Seismic Vulnerability ◽  
Base Isolation ◽  
Cost Effective ◽  
Storage Tanks ◽  
Modes Of Failure ◽  
Liquid Storage ◽  
Near Fault Earthquakes ◽  
Friction Pendulum ◽  
The Cost

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.

Parametric study of stochastic seismic responses of base-isolated liquid storage tanks under near-fault and far-fault ground motions

2016 ◽  
Vol 24 (24) ◽  
pp. 5747-5764 ◽  
Author(s):  
Sina Safari ◽  
Reza Tarinejad
Keyword(s):  
Base Isolation ◽  
Seismic Analysis ◽  
Ground Motions ◽  
Characteristic Parameter ◽  
Statistical Linearization ◽  
Storage Tanks ◽  
Earthquake Excitation ◽  
Isolation System ◽  
Near Fault ◽  
Liquid Storage

Seismic response of base isolated steel liquid storage tanks is investigated in this study by a stochastic approach in frequency domain. For the purpose of evaluating different frequency contents of seismic events on the responses of fixed and isolated tanks, the earthquake excitation is characterized by power spectral density function. Since earthquake is a random process, stochastic seismic analysis is used and root mean square response predicts behavior of system properly. Two types of isolation system are assumed and nonlinear behavior of base isolation systems are developed by an iterative statistical linearization scheme. The study demonstrates the influence of each characteristic parameter of the storage tanks and isolation system and also excitation features. It is confirmed that near-fault earthquake excitations amplify the overall response of the system. Base isolation is known as an effective technique to reduce responses appropriately. It is demonstrated that the sloshing responses of the tanks is significantly reduced by sliding bearing. Further, excitation parameters, PGV/PGA ratio of records and pulse period in near-fault ground motions, that represent differences in two sets of earthquakes are defined to recognize variation of responses.

The Material Behavior and Isolation Benefits of Ball Pendulum System

2006 ◽  
Author(s):  
C. S. Tsai ◽  
Ching-Pei Tsou ◽  
Yung-Chang Lin ◽  
Mei-Ju Chen ◽  
Wen-Shin Chen
Keyword(s):  
Base Isolation ◽  
Ground Motions ◽  
Material Behavior ◽  
Shaking Table ◽  
Ground Acceleration ◽  
Isolation System ◽  
Pendulum System ◽  
Damping Material ◽  
Base Isolation System ◽  
Damping Materials

Earthquake ground motions often result in significant seismic disasters. Strong ground motions will not only cause damage, but may also cause the collapse of structures. People have to face up the suffering from the earthquake damage, and the indirect loss which may be more serious than the damage itself. For example, the antique breaks in museum, and the equipment damages in hi-tech industries are often in huge loss. Therefore, in addition to promoting the earthquake-resistant capacity of a structure, it is also important to ensure the safety of the ancient valuable objects and the instruments in structures. For this reason, this study is aimed at a new damped rolling type base isolation system named the ball pendulum system (BPS) to be installed under the motion sensitive equipment and proceeding all related studies. The isolation device can isolate earthquake from buildings or equipments in any direction by rolling motions and damping materials. This study has conducted a series of component tests and shaking table tests for examining the behaviors of materials and earthquake proof benefits. From the experiment results, it is found that this device can reduce more than 80% of acceleration response under earthquakes with peak ground acceleration of 450 gal. So, the new rolling isolation system with a damping material can be recognized as a feasible and promising way in mitigating the seismic response of equipment.

Effect of Velocity Dependence on Sliding Characteristic of Sliding Types of Base Isolation Systems Each With Numerous Sliding Interfaces

2011 ◽  
Author(s):  
C. S. Tsai ◽  
H. C. Su ◽  
T. C. Chiang
Keyword(s):  
Base Isolation ◽  
Velocity Dependence ◽  
Analysis Software ◽  
Pendulum System ◽  
Sliding Interfaces ◽  
Velocity Effect ◽  
Isolation Systems ◽  
Friction Pendulum ◽  
The Given ◽  
Base Isolators

Current structural analysis software programs offer few if any applicable device-specific hysteresis rules or nonlinear elements considering the velocity effect on the mechanical behavior of the multiple friction pendulum system (MFPS) with numerous sliding interfaces. Based on the concept of subsystems, here we propose an equivalent series system that adopts existing nonlinear elements with parameters systematically calculated and mathematically proven through rigorous derivations to take into account the velocity dependence effect on the sliding behavior of the sliding interfaces in the sliding type base isolators. Evaluations of the velocity dependence effect on the features of the sliding motions on numerous sliding interfaces have also been carried out. Results from the given examples demonstrate that the sliding motions of sliding interfaces considering velocity dependence behave quite differently from those excluding the effect of velocity dependence.

scholarly journals THE INVESTIGATION BASE ISOLATOR IN CONTROLLING THE RESPONSE OF THE STRUCTURES DURING EARTHQUAKES

2018 ◽  
Vol 1 (18) ◽  
Author(s):  
Barghlame Hadi ◽  
Gavgani Hojjat Hashempour
Keyword(s):  
Base Isolation ◽  
Comparative Investigation ◽  
Pendulum System ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
Fixed Base ◽  
High Damping Rubber ◽  
Isolation Systems ◽  
Friction Pendulum ◽  
Base Isolators

Base isolation systems are among the most successful and widely applied methods of mitigatingstructural vibration and damage during seismic events. These systems have been installed in numerousfull-scale structures all around. There are three principal types of base isolators: Lead Rubber Bearing(LRB), High Damping Rubber Bearing (HDRB), and Friction Pendulum System (FPS). It is necessaryto extensively examine the response of different LRB isolators—by combining them with re-centeringand damping properties for isolated steel frame buildings experiencing several NF ground motions. Thepresent research uses comparative-descriptive methodology and application in terms of objectives. Thedata needed for the study were collected using library references and through reviewing related studiesconducted in the past in the same field.Results of the current comparative investigation indicated significant reductions in the storey drift,shear, and acceleration and increment in the storey displacement. According to the findings of thecurrent study, base isolators provide flexibility to massive structures against earthquakes. Thesestructures are situated on rigid soils. Moreover, base isolation was found to be the most effective incontrolling the response of the structures during earthquakes. Finally, shear, storey drift, and storeydisplacement reduce due to the use of base isolators as compared to the fixed-base structure.

Earthquake Protection of Liquid Storage Tanks by Sliding Isolation Bearings

2015 ◽  
Author(s):  
Eren Uckan ◽  
Bulent Akbas ◽  
Fabrizio Paolacci ◽  
Jashue Shen ◽  
Emre Abalı
Keyword(s):  
Base Isolation ◽  
Ground Motions ◽  
The Other ◽  
Lumped Parameter Model ◽  
Appreciable Amount ◽  
Storage Tanks ◽  
Base Shear ◽  
Isolation System ◽  
Liquid Storage ◽  
Sliding Isolation

Liquid storage tanks are critical components of industrial facilities since damage to such structures may cause spreading of hazardous material and environmental pollution. Tanks exhibit mainly two different seismic behaviors one of which is the long period movements due to sloshing of the liquid and the other is the impulsive vibrations generated as a result of the fluid structure interaction phenomena at higher frequencies. The overall base shear is the combination of these two loads. The seismic base isolation aims to control the impulsive load as it has appreciable amount of contribution to the base shear values. Among various types, the curved surface sliding bearings (FPS) are commonly used in liquid tanks since provide isolation periods which is independent of the tank weight (liquid height). In this paper a parametric analysis has been performed to investigate the efficiency of FPS bearings. The numerical model is based on the Haroun and Housner’s simplified lumped parameter model in which the sloshing and fluid-tank interactions are modeled by convective and impulsive masses, respectively. The effectiveness of the isolation system was investigated under a series of ground motions, isolation periods and tank aspect (slenderness) ratios. Results indicated that depending on the characteristics of the ground motion, the response of the isolated tank can be reduced in appreciable amounts as compared to the conventionally constructed one. On the other hand, some detrimental effects were also observed in lower isolation periods (Tb=2s) particularly in medium slender tanks under near fault ground motions. This undesirable situation was avoided by using higher isolation periods (Tb =3s) without much affecting the bearing displacements.

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