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.

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.

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.

scholarly journals The seismic response of elevated liquid storage tanks isolated by lead-rubber bearings

2003 ◽  
Vol 36 (3) ◽  
pp. 141-164 ◽  
Author(s):  
M.K. Shrimali ◽  
R.S. Jangid
Keyword(s):  
Seismic Response ◽  
Seismic Isolation ◽  
Degree Of Freedom ◽  
Earthquake Ground Motion ◽  
Storage Tanks ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Liquid Storage ◽  
Tower Structure ◽  
Lumped Masses

The seismic response of elevated liquid storage tanks isolated by the lead-rubber bearing is investigated under real earthquake ground motion. Two types of isolated tank models are considered in which the bearings are placed at the base and top of the tower structure. The tank liquid is modelled as lumped masses referred as convective mass, impulsive mass and rigid mass. The corresponding stiffness associated with these lumped masses has been worked out using the properties of the tank wall and liquid mass based on simple single-degree-of-freedom concepts. The mass of the tower structure is lumped equally at top and bottom. The assembled equations of motion are solved by Newmark's step-by-step method with iteration. The seismic response of two types of tanks, namely slender and broad tanks is obtained and a parametric study is carried out to study the effects of important system parameters on the effectiveness of seismic isolation. The various important parameters considered are the tank aspect ratio, the time period of the tower structure, damping and the lime period of the isolation system. It has been observed that the earthquake response of the isolated tank is reduced significantly. Further, it is observed that the isolation is more effective for the tank with a stiff tower structure in comparison to flexible towers. In addition, a simplified analysis is also presented to evaluate the response of the elevated tanks using a two-degrees-of-freedom model and two single degree-of-freedom models. It is observed that the proposed methods predict accurately the seismic response of elevated liquid storage tanks with less computational efforts.

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.

Effects of Base Uplifting on the Seismic Response of Unanchored Liquid Storage Tanks

2012 ◽  
Author(s):  
Maria Vathi ◽  
Spyros A. Karamanos
Keyword(s):  
Seismic Response ◽  
Pushover Analysis ◽  
Hydrodynamic Pressure ◽  
Base Plate ◽  
Seismic Loading ◽  
Storage Tanks ◽  
Liquid Storage ◽  
Detailed Simulation ◽  
Steel Tank ◽  
Static Pushover Analysis

Unanchored liquid storage tanks under strong earthquake loading tend to uplift. In the present study, the effects of base uplifting on the seismic response of unanchored tanks are presented with emphasis on elephant’s foot buckling, base plate strength and shell-to-base connection capacity. Towards this purpose, base uplifting mechanics is analyzed through a detailed simulation of the tank using non-linear finite elements, and a static pushover analysis is conducted that considers the hydrodynamic pressure distribution due to seismic loading on the tank wall and the base plate. The uplifting provisions from EN 1998-4 and API 650 Appendix E standards are briefly described. Numerical results for a typical 27.8-meter-diameter steel tank are compared with the above design provisions.

Seismic response analysis of adjacent liquid-storage tanks

2016 ◽  
Vol 45 (11) ◽  
pp. 1779-1796 ◽  
Author(s):  
Konstantinos Mykoniou ◽  
Christoph Butenweg ◽  
Britta Holtschoppen ◽  
Sven Klinkel
Keyword(s):  
Seismic Response ◽  
Response Analysis ◽  
Storage Tanks ◽  
Seismic Response Analysis ◽  
Liquid Storage
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