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.

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.

Performance of bi-directional elliptical rolling rods for base isolation of buildings under near-fault earthquakes

2017 ◽  
Vol 21 (5) ◽  
pp. 675-693 ◽  
Author(s):  
Aruna Rawat ◽  
Naseef Ummer ◽  
Vasant Matsagar
Keyword(s):  
Base Isolation ◽  
Ground Motions ◽  
Frictional Resistance ◽  
Curved Surface ◽  
Isolation System ◽  
Near Fault ◽  
Earthquake Ground Motions ◽  
Base Isolation System ◽  
Near Fault Earthquakes ◽  
Storey Building

Rolling base isolation system provides effective isolation to the structures from seismic base excitations by virtue of its low frictional resistance. Herein, dynamic analysis of flexible-shear type multi-storey building mounted on orthogonally placed elliptical rolling rod base isolation systems subjected to bi-directional components of near-fault earthquake ground motions is presented. The orthogonally placed rods would make it possible to resist the earthquake forces induced in the structure in both the horizontal directions. The curved surface of these elliptical rods has a self-restoring capability due to which the magnitude of peak isolator displacement and residual displacement is reduced. The roughness of the tempered curved surface of the rollers dissipates energy in motion due to frictional damping. The seismic performance of the multi-storey building mounted on the elliptical rolling rod base isolation system is compared with that mounted on the sliding pure-friction and cylindrical rolling rod systems. Parametric studies are conducted to examine the behavior of the building for different superstructure flexibilities, eccentricities of the elliptical rod, and coefficients of friction. It is concluded that the elliptical rolling rod base isolation system is effective in mitigation of damaging effects of the near-fault earthquake ground motions in the multi-storey buildings. Even under the near-fault earthquake ground motions, the base-isolated building mounted on the elliptical rolling rods shows considerable reduction in seismic response. The isolator displacement with the elliptical rolling rod base isolation system is less in comparison to the pure-friction and cylindrical rolling rod systems.

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.

Seismic Analysis of Base-Isolated San Bernardino County Building

1992 ◽  
Vol 8 (4) ◽  
pp. 605-633 ◽  
Author(s):  
Bruce F. Maison ◽  
Carlos E. Ventura
Keyword(s):  
Base Isolation ◽  
Seismic Analysis ◽  
Seismic Gap ◽  
Elastic Model ◽  
San Bernardino County ◽  
Earthquake Excitation ◽  
Isolation System ◽  
Soft Story ◽  
Linear Elastic ◽  
Linear Elastic Model

The authors investigate the seismic behavior of an existing base isolated building and interpret its recorded response to the 1990 Upland California earthquake. They formulate a linear-elastic model that accurately represents the building during the earthquake and infer its response behaviors. Additional analyses using severe earthquake excitations demonstrate the building behavior in major events and hypothetical seismic gap pounding situations. Key findings include the following: • The Upland earthquake resulted in relatively low intensity shaking at the site, and the building did not exhibit a classic soft story effect in the isolation system. • A linear-elastic model can accurately idealize the building during this event. • Under major earthquake excitation, base isolation can lead to peak story drifts, shears, overturning moments, and accelerations that are much smaller than those of nonisolated buildings. • Pounding at seismic gaps can produce large story drifts, shears and accelerations. These peak pounding responses can be greater than those from nonisolated buildings (i.e., having no pounding).

Seismic response of base isolated liquid storage tanks to real and simulated near fault pulse type ground motions

2018 ◽  
Vol 112 ◽  
pp. 58-68 ◽  
Author(s):  
Eren Uckan ◽  
Önder Umut ◽  
Fatma Nurten Sisman ◽  
Shaghayegh Karimzadeh ◽  
Aysegul Askan
Keyword(s):  
Seismic Response ◽  
Ground Motions ◽  
Storage Tanks ◽  
Near Fault ◽  
Liquid Storage ◽  
Pulse Type

scholarly journals Influence of Elastomeric Bearings in Tension on the Seismic Performance of Base-Isolated r.c. Buildings

2020 ◽  
Vol 11 (1) ◽  
pp. 82
Author(s):  
Fabio Mazza ◽  
Mirko Mazza
Keyword(s):  
Base Isolation ◽  
Nonlinear Models ◽  
Vertical Component ◽  
Computer Code ◽  
Nonlinear Phenomena ◽  
Isolation System ◽  
Elastomeric Bearings ◽  
Near Fault ◽  
Base Isolation System ◽  
Near Fault Earthquakes

Elastomeric bearings are commonly used in base-isolation systems to protect the structures from earthquake damages. Their design is usually developed by using nonlinear models where only the effects of shear and compressive loads are considered, but uncertainties still remain about consequences of the tensile loads produced by severe earthquakes like the near-fault ones. The present work aims to highlight the relapses of tension on the response of bearings and superstructure. To this end, three-, seven- and ten-storey r.c. framed buildings are designed in line with the current Italian seismic code, with a base-isolation system constituted of High-Damping-Rubber Bearings (HDRBs) designed for three values of the ratio between the vertical and horizontal stiffnesses. Experimental and analytical results available in literature are used to propose a unified nonlinear model of the HDRBs, including cavitation and post-cavitation of the elastomer. Nonlinear incremental dynamic analyses of the test structures are carried out using a homemade computer code, where other models of HDRBs considering only some nonlinear phenomena are implemented. Near-fault earthquakes with comparable horizontal and vertical components, prevailing horizontal component and prevailing vertical component are considered as seismic input. Numerical results highlight that a precautionary estimation of response parameters of the HDRBs is attained referring to the proposed model, while its effects on the nonlinear response of the superstructure are less conservative.

Sign in / Sign up

Export Citation Format

Share Document