A COMPARATIVE STUDY OF PERFORMANCE OF VARIOUS ISOLATION SYSTEMS FOR LIQUID STORAGE TANKS

2002 ◽  
Vol 02 (04) ◽  
pp. 573-591 ◽  
Author(s):  
M. K. SHRIMALI ◽  
R. S. JANGID
Keyword(s):  
Comparative Study ◽  
Seismic Isolation ◽  
Deformation Behaviour ◽  
Storage Tanks ◽  
Step Method ◽  
Earthquake Excitation ◽  
Restoring Force ◽  
Liquid Storage ◽  
Wide Range ◽  
Isolation Systems

A comparative study of performance of various isolation systems for liquid storage tanks is investigated under real earthquake ground motions. The various base isolation systems considered are the laminated rubber bearings (with and without lead core) and sliding isolation systems (with and without restoring force). The isolated liquid storage tank is idealized with three-degrees-of-freedom associated with convective, impulsive and rigid mass under uni-directional earthquake excitation. Since the force-deformation behaviour of the isolation systems is non-linear, as a result, the equations of motion are solved numerically by step-by-step method. In order to measure the effectiveness of the isolation systems, the seismic response of the isolated liquid storage tanks is compared with the corresponding response of non-isolated tanks. Further, the effectiveness of the isolation is also explored for wide range of practical liquid storage tanks considering the influence of tank aspect ratio. It is observed that the isolation systems are quite effective in attenuating the earthquake acceleration transmitted to the tank, which reduces the design seismic forces significantly. Further, it is also found that the sliding type isolation systems are more effective in controlling the response of liquid storage tanks in comparison to the elastomeric bearings. Among the various sliding systems, the resilient-friction base isolator is found to be most effective for seismic isolation of the tanks.

scholarly journals Response of Base-Isolated Liquid Storage Tanks

2004 ◽  
Vol 11 (1) ◽  
pp. 33-45 ◽  
Author(s):  
M.B. Jadhav ◽  
R.S. Jangid
Keyword(s):  
Seismic Response ◽  
Seismic Isolation ◽  
Equations Of Motion ◽  
Approximate Model ◽  
Storage Tanks ◽  
Step Method ◽  
Earthquake Excitation ◽  
System Parameters ◽  
Liquid Storage ◽  
Isolation Systems

Seismic response of liquid storage tanks isolated by elastomeric bearings and sliding system is investigated under real earthquake ground motions. The continuous liquid mass of the tank is modeled as lumped masses known as sloshing mass, impulsive mass and rigid mass. The coupled differential equations of motion of the system are derived and solved in the incremental form using Newmark's step-by-step method with iterations. The seismic response of isolated tank is studied to investigate the comparative effectiveness of various isolation systems. A parametric study is also carried out to study the effect of important system parameters on the effectiveness of seismic isolation for liquid storage tanks. The various important parameters considered are: (i) aspect ratio of the tank and (ii) the time period of the isolation systems. It was observed that both elastomeric and sliding systems are found to be effective in reducing the earthquake forces of the liquid storage tanks. However, the elastomeric bearing with lead core is found to perform better in comparison to other systems. Further, an approximate model is proposed for evaluation of seismic response of base-isolated liquid storage tanks. A comparison of the seismic response evaluated by the proposed approximate method and an exact approach is made under different isolation systems and system parameters. It was observed that the proposed approximate analysis provides satisfactory response estimates of the base-isolated liquid storage tanks under earthquake excitation.

Seismic Response of Base-Isolated Liquid Storage Tanks

2003 ◽  
Vol 9 (10) ◽  
pp. 1201-1218 ◽  
Author(s):  
M. K. Shrimali ◽  
R. S. Jangid
Keyword(s):  
Seismic Response ◽  
Deformation Behavior ◽  
Seismic Isolation ◽  
Storage Tanks ◽  
Base Shear ◽  
Step Method ◽  
Isolation System ◽  
System Parameters ◽  
Liquid Mass ◽  
Liquid Storage

We investigate the seismic response of liquid storage tanks isolated by lead-rubber bearings. The force-deformation behavior of the bearings is considered as bi-linear modeled by the Wen equation. The continuous liquid mass of the tank is modeled as a sloshing mass, impulsive mass and rigid mass. The corresponding stiffness associated with these masses has been worked out depending upon the properties of the tank wall and liquid mass. The governing equations of motion of the three-degrees-of-freedom model of the isolated liquid storage tank are derived. Since the force-deformation behavior of the bearings is non-linear, as a result, the seismic response is obtained using the Newmark step-by-step method under several recorded earthquake ground motions. The responses of two types of tanks, namely slender and broad, are compared with the corresponding response without an isolation system in order to investigate the effectiveness of the isolation system. A parametric study is also carried out to study the effects of important system parameters on the effectiveness of seismic isolation for liquid storage tanks. The various important parameters considered are the aspect ratio of the tank, period, damping and the yield strength of the isolation system. It has been observed that the seismic isolation of the tanks is quite effective and the response of isolated liquid storage tanks is significantly influenced by the above system parameters. There is an optimum value of isolation damping for which the base shear in the tank attains the minimum value. Therefore, increasing the bearing damping beyond a certain value decreases the bearing and sloshing displacements but it increases the base shear.

Dynamic Analysis of Liquid Storage Tanks with Sliding Systems

2003 ◽  
Vol 6 (2) ◽  
pp. 145-158 ◽  
Author(s):  
M. K. Shrimali ◽  
R. S. Jangid
Keyword(s):  
Seismic Response ◽  
Frictional Force ◽  
Seismic Isolation ◽  
Earthquake Ground Motion ◽  
Hysteretic Model ◽  
Storage Tanks ◽  
Step Method ◽  
Conventional Model ◽  
Liquid Mass ◽  
Liquid Storage

Dynamic response of liquid storage tanks isolated by the sliding systems is investigated under real earthquake ground motion. The frictional force of sliding systems is modelled by conventional and hysteretic models. The continuous liquid mass is lumped as convective mass, impulsive mass and rigid mass. The corresponding stiffness associated with these lumped masses is worked out depending upon the properties of the tank wall and liquid mass. The governing equations of motion of the tank with sliding system are derived and solved by Newmark's step-by-step method with iterations. The frictional force mobilized at the interface of the sliding system is assumed to be velocity dependent. For comparative study, the seismic response of isolated liquid storage tank obtained by the conventional model is compared with the corresponding response obtained by the hysteretic model. In order to measure the effectiveness of isolation system, the seismic response of isolated tank is compared with that of the non-isolated tank. A parametric study is also conducted to study the effects of aspect ratio of tank on the effectiveness of seismic isolation of liquid storage tanks. It is found that the sliding systems are quite effective in reducing the earthquake response of liquid storage tanks. In addition, the conventional and the hysteretic model of the sliding system predict the same seismic response of liquid storage tanks. However, the conventional model is relatively more computationally efficient as compared to the hysteretic model.

Sliding Isolation System for Bridges: Experimental Study

1992 ◽  
Vol 8 (3) ◽  
pp. 321-344 ◽  
Author(s):  
M. C. Constantinou ◽  
Allaoua Kartoum ◽  
A. M. Reinhorn ◽  
Paul Bradford
Keyword(s):  
Seismic Isolation ◽  
Earthquake Excitation ◽  
Restoring Force ◽  
Additional Energy ◽  
Isolation System ◽  
Sliding Isolation ◽  
Wide Range ◽  
Energy Dissipation Capacity ◽  
Bridge Bearings ◽  
Good Agreement

A seismic isolation system for bridges has been tested on a shake table. The system consisted of Teflon disc bridge bearings and displacement control devices. These devices provided restoring force for re-centering the bridge during earthquake excitation, additional energy dissipation capacity and rigidity for service loading. The tests were carried out with a 51-kip model which was subjected to strong recorded earthquake motions with a wide range of frequency content and to simulated motions compatible with CalTrans 0.6g design spectra. In all tests the isolated deck responded with peak acceleration less than the peak table acceleration and peak bearing displacement less than the peak table displacement. Results from an analytical model show very good agreement with experimental results.

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.

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.

scholarly journals VISCOELASTIC DAMPER CONNECTED TO ADJACENT STRUCTURES INVOLVING SEISMIC ISOLATION

2005 ◽  
Vol 11 (4) ◽  
pp. 309-322 ◽  
Author(s):  
Vasant Annasaheb Matsagar ◽  
Radhey Shyam Jangid
Keyword(s):  
Seismic Isolation ◽  
Equations Of Motion ◽  
Viscoelastic Damper ◽  
Step Method ◽  
Viscoelastic Dampers ◽  
Adjacent Structures ◽  
Fixed Base ◽  
Real Earthquake ◽  
Isolation Systems ◽  
Incremental Form

The seismic response of multi‐storied base‐isolated structure to various types of isolation systems connected using viscoelastic dampers to the adjacent dissimilar base‐isolated or fixed‐base structure is investigated. The multi‐storied structures are modelled as a shear type structures with lateral degree‐of‐freedom at each floor, which are connected at different floor levels by viscoelastic dampers. The performance of this combination is studied by deriving the governing equations of motion and solving it in the incremental form using Newmark's step‐by‐step method of integration. The variation of top floor absolute acceleration of both the buildings and bearing displacement under different real earthquake ground motions is computed to study the behaviour and effectiveness of resulting connected system. It is concluded that connecting the two adjacent base‐isolated buildings with the viscoelastic dampers is useful in controlling large bearing displacements in the base‐isolated structures thereby eliminating the isolator damages arising due to instability at these large displacements or pounding with adjacent ground structures during earthquakes. The viscoelastic damper connection between adjacent structures is found to be most effective when the adjacent base‐isolated and fixed‐base buildings are connected. Such scheme is hence useful in upgrading the seismic performance of existing fixed‐base structures adjacent to a base‐isolated structure.

Sign in / Sign up

Export Citation Format

Share Document