EFFECTIVENESS OF SEISMIC ISOLATION FOR CABLE-STAYED BRIDGES

2006 ◽  
Vol 06 (01) ◽  
pp. 77-96 ◽  
Author(s):  
B. B. SONEJI ◽  
R. S. JANGID
Keyword(s):  
Seismic Response ◽  
Seismic Isolation ◽  
Damping Ratio ◽  
Time History ◽  
Time Interval ◽  
Lumped Mass ◽  
Pendulum System ◽  
Isolation Systems ◽  
Rubber Bearings ◽  
Cable Stayed Bridges

This paper investigates the effectiveness of elastomeric and sliding types of isolation systems for the seismic response control of cable-stayed bridges. A simplified two-dimensional lumped-mass finite-element model of the Quincy Bay-view Bridge at Illinois was developed for the investigation. The seismic isolation of cable-stayed bridges is achieved using three different isolators, namely, high damping rubber bearings (HDRB), lead rubber bearings (LRB) and friction pendulum system (FPS). Time history analysis is performed for the bridge with four different earthquake ground motions applied in the longitudinal direction using Newmark's method with linear variation of acceleration over the time interval. The seismic response of the isolated cable-stayed bridge is compared with that of the bridge with no isolation system. The results show that the isolation systems are effective for reducing the absolute acceleration of the deck and the base shear response of the tower. Further, a parametric study is performed by varying the damping ratio, yield strength and friction coefficient of HDRB, LRB and FPS to investigate the influence of these parameters on the seismic response of the bridge. From such a study, optimal values can be found for the isolators for reducing the bridge responses.

Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities: Part 3 — Seismic Response of Crossover Piping for Seismic Isolation System

2014 ◽  
Author(s):  
Akihito Otani ◽  
Teruyoshi Otoyo ◽  
Hideo Hirai ◽  
Hirohide Iiizumi ◽  
Hiroshi Shimizu ◽  
...  
Keyword(s):  
Seismic Response ◽  
Nuclear Power ◽  
Seismic Isolation ◽  
Evaluation Method ◽  
Response Spectrum ◽  
Time History ◽  
Response Analysis ◽  
Isolation System ◽  
Isolation Systems ◽  
Seismic Isolation Systems

This paper, which is part of the series entitled “Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities”, shows the linear seismic response of crossover piping installed in a seismically isolated plant. The crossover piping, supported by both isolated and non-isolated buildings, deforms with large relative displacement between the two buildings and the seismic response of the crossover piping is caused by two different seismic excitations from the buildings. A flexible and robust structure is needed for the high-pressure crossover piping. In this study, shaking tests on a 1/10 scale piping model and FEM analyses were performed to investigate the seismic response of the crossover piping which was excited and deformed by two different seismic motions under isolated and non-isolated conditions. Specifically, as linear response analysis of the crossover piping, modal time-history analysis and response spectrum analysis with multiple excitations were carried out and the applicability of the analyses was confirmed. Moreover, the seismic response of actual crossover piping was estimated and the feasibility was evaluated.

On the Effectiveness of Two Isolation Systems for the Seismic Protection of Elevated Tanks

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Fabrizio Paolacci
Keyword(s):  
Time History ◽  
Seismic Protection ◽  
Base Shear ◽  
Lumped Mass ◽  
High Damping Rubber Bearings ◽  
Elevated Tanks ◽  
High Damping Rubber ◽  
Isolation Systems ◽  
The Stability ◽  
Rubber Bearings

This paper deals with the effectiveness of two isolation systems for the seismic protection of elevated steel storage tanks. In particular, the performance of high damping rubber bearings (HDRB) and friction pendulum isolators (FPS) has been analyzed. As case study, an emblematic example of elevated tanks collapsed during the Koaceli Earthquake in 1999 at Habas pharmaceutics plant in Turkey is considered. A time-history analysis conducted using lumped mass models demonstrates the high demand in terms of base shear required to the support columns and their inevitable collapse due to the insufficient shear strength. A proper design of HDRB and FPS isolator according to the EN1998 and a complete nonlinear analysis of the isolated tanks proved the high effectiveness of both isolation systems in reducing the response of the case tank. Actually, the stability conditions imposed by the code and a reduced level of convective base shear obtained with the second isolation typology suggests the use of FPS isolators rather than HDRB devices.

Seismic Isolation Design for Approach Spans of Suiwei Bridge in Wenchuan

2011 ◽  
Vol 71-78 ◽  
pp. 1444-1450
Author(s):  
Wen Zheng Zhu ◽  
Zhong Gen Xu
Keyword(s):  
Energy Dissipation ◽  
Seismic Isolation ◽  
Design Method ◽  
Response Spectrum ◽  
Damping Ratio ◽  
Time History ◽  
Large Earthquake ◽  
Bridge Design ◽  
Dynamic Time ◽  
Rubber Bearings

The process and thought for the approach bridge of Suiwei bridge design using the method of isolation and energy dissipation were proposed in this paper. The concept of protecting a bridge from the damaging effects of an earthquake by introducing isolating bearings to isolate it from the moving ground is an attractive one. Firstly, the sizes of the laminated rubber bearings and the dia- meters of lead plugs are calculated with static analysis. Then the internal forces of the piers and the damping ratio of the isolated bridge needed to restrict the seismic deformation to 8cm during earth- quakes with seldom intensity were calculated using the Response Spectrum Method, and the result verified with dynamic time history method demonstrates that the Response Spectrum Design Method can restrict the girder displacement to 8cm during large earthquake and reach the goal of 25 percent shock reduction. The design process can be of reference to the bridge design with isolation and energy dissipation.

On the Effectiveness of Two Isolation Systems for the Seismic Protection of Elevated Tanks

2014 ◽  
Author(s):  
Fabrizio Paolacci
Keyword(s):  
Time History ◽  
Seismic Protection ◽  
Base Shear ◽  
Lumped Mass ◽  
Isolation System ◽  
High Damping Rubber Bearings ◽  
Elevated Tanks ◽  
High Damping Rubber ◽  
Isolation Systems ◽  
Rubber Bearings

This paper deals with the effectiveness of two isolation system for the seismic protection of elevated steel storage tanks. In particular the performance of High Damping Rubber Bearings and Friction Pendulum isolators has been analyzed. As case study an emblematic example of elevated tanks collapsed during the Koaceli Earthquake in 1999 at Habas Pharmaceutics plant in Turkey has been considered. A time-history analysis conducted using lumped mass models demonstrated the high demand in terms of base shear required to the support columns and their inevitable collapse due to the insufficient shear strength. A proper design of HDRB and FPS isolator and a complete non-linear analysis of the isolated tanks proved the high effectiveness of both isolation systems in reducing the response of the case tank. Actually, a reduced level of displacements of isolators and a reduced level of convective base shear obtained with the second isolation typology, suggested the used of FPS isolators rather than HDRB.

scholarly journals A comparative study of base isolation devices in light rail transit structure featured with lead rubber bearing and friction pendulum system

2018 ◽  
Vol 195 ◽  
pp. 02013
Author(s):  
Santi Nuraini ◽  
Asdam Tambusay ◽  
Priyo Suprobo
Keyword(s):  
Seismic Isolation ◽  
Time History ◽  
Light Rail ◽  
Rail Transit ◽  
Light Rail Transit ◽  
Pendulum System ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
Friction Pendulum ◽  
Friction Pendulum System

Advanced nonlinear analysis in light rail transit (LRT) structures has been undertaken to examine the influence of seismic isolation devices for reducing seismic demand. The study employed the use of two types of commercially available bearings, namely lead rubber bearing (LRB) and friction pendulum system (FPS). Six LRT structures, designed to be built in Surabaya, were modelled using computer-aided software SAP2000, where each of the three structures consisted of three types of LRB and FPS placed onto the pier cap to support the horizontal upper-structural member. Nonlinear static pushover and dynamic time history analysis with seven improved ground motion data was performed to gain improved insights on the behavioural response of LRT structures, allowing one to fully understand the supremacy of seismic isolations for protecting the structure against seismic actions. It is shown that both devices manage to isolate seismic forces, resulting in alleviation of excessive base shear occurring at the column. In addition, it is noticeable that the overall responses of LRB and FPS shows marginal discrepancies, suggesting both devices are interchangeable to be used for LRT-like structures.

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.

Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities: Part 2 — Application of CCFS Method to the Multiply Supported Systems

2014 ◽  
Author(s):  
Koichi Tai ◽  
Keisuke Sasajima ◽  
Shunsuke Fukushima ◽  
Noriyuki Takamura ◽  
Shigenobu Onishi
Keyword(s):  
Power Plant ◽  
Nuclear Power ◽  
Seismic Isolation ◽  
Evaluation Method ◽  
Time History ◽  
Piping System ◽  
History Analysis ◽  
Piping Systems ◽  
Isolation Systems ◽  
Seismic Isolation Systems

This paper provides a part of series of “Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities”. Paper is focused on the seismic evaluation method of the multiply supported systems, as the one of the design methodology adopted in the equipment and piping system of the seismic isolated nuclear power plant in Japan. Many of the piping systems are multiply supported over different floor levels in the reactor building, and some of the piping systems are carried over to the adjacent building. Although Independent Support Motion (ISM) method has been widely applied in such a multiply supported seismic design of nuclear power plant, it is noted that the shortcoming of ignoring correlations between each excitations is frequently misleaded to the over-estimated design. Application of Cross-oscillator, Cross-Floor response Spectrum (CCFS) method, proposed by A. Asfura and A. D. Kiureghian[1] shall be considered to be the excellent solution to the problems as mentioned above. So, we have introduced the algorithm of CCFS method to the FEM program. The seismic responses of the benchmark model of multiply supported piping system are evaluated under various combination methods of ISM and CCFS, comparing to the exact solutions of Time History analysis method. As the result, it is demonstrated that the CCFS method shows excellent agreement to the responses of Time History analysis, and the CCFS method shall be one of the effective and practical design method of multiply supported systems.

Seismic Isolation Analysis on Long-Span Platform Bridge Connecting Twin-Tower Structures

2011 ◽  
Vol 255-260 ◽  
pp. 1225-1229
Author(s):  
Huang Sheng Sun ◽  
Li Nuo Cheng ◽  
Shi Hai Chen
Keyword(s):  
Seismic Isolation ◽  
Seismic Responses ◽  
One Pot ◽  
Isolation System ◽  
High Position ◽  
Long Span ◽  
Steel Truss ◽  
Story Drift ◽  
Isolation Systems ◽  
Rubber Bearings

In order to mitigate the seismic response of twin-tower structure linked by a steel truss platform bridge, as well as to reduce temperature force in the steel truss, eight groups of combined isolation system, each consisting of one pot-type bearing and four rubber bearings, were designed to connect the upper platform bridge to the lower supporting reinforced concrete towers. The features and working principles of the high-position isolation system were described. Then the seismic responses, including displacement, story drift and floor acceleration, of the structure with the isolation systems were calculated and compared with those of the structure with hinge joints in lieu of isolation. It is found that both the structural seismic responses and the temperature forces in the large-span mega-truss structure can be reduced by the high-position isolation system.

Seismic Isolation Retrofit of an Office Building Using Friction Pendulum System

2014 ◽  
Vol 578-579 ◽  
pp. 1361-1365
Author(s):  
Lin Liu ◽  
Xuan Min Li ◽  
Wei Tian
Keyword(s):  
Seismic Isolation ◽  
Base Isolation ◽  
Time History ◽  
Nonlinear Behavior ◽  
Office Building ◽  
Nonlinear Time History Analysis ◽  
Isolation System ◽  
Pendulum System ◽  
Nonlinear Time History ◽  
Friction Pendulum

Friction Pendulum Systems have been used as base isolation systems for both new construction and retrofit around the world. This paper presented its implementation in an office building located in Shanghai. To evaluate its impact on seismic performance of the retrofitted structure, models are needed to capture the intricate nonlinear behavior of both structural components and isolator elements. Nonlinear time history analysis of the building for the original and retrofitted cases was conducted to assess the efficiency of the isolation system at the high earthquake level. The numerical results indicate that the retrofitted structure experiences significantly less damage and less deformation due to the shake isolation and energy dissipation through the isolators.

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