Research on the Effect of Combined Seismic Isolation System

2012 ◽  
Vol 446-449 ◽  
pp. 3299-3303
Author(s):  
Xi Sen Fan ◽  
Ting Lei Tian
Keyword(s):  
Seismic Response ◽  
Seismic Isolation ◽  
Base Isolation ◽  
Seismic Responses ◽  
Combined System ◽  
Isolation System ◽  
Lead Rubber Bearings ◽  
Base Isolation System ◽  
Rubber Bearings ◽  
The Relationship

The isolation system between the upper structure and the foundation could reduce the seismic response of the former. A system combined of sliding and lead rubber bearings (LRB) is more effective in seismic isolation than using the later alone. In this research, the seismic responses of a building which was set with LRB and a combined system (the proportions between the sliding and LRB were 1/6, 1/4 and 1/3) respectively were analyzed and compared to that of the building without base isolation system to investigate the effect of seismic isolation. The relationship between isolation coefficient and the proportion of bearings was studied. The results show that the combined system could reduce the seismic response of structure, and it is more effective in seismic isolation if the leading bearing is relatively more.

Influence of the Strain Hardening of HDRBs in the Evaluation of the Seismic Response of a RC Base Isolated Structure

2012 ◽  
Vol 602-604 ◽  
pp. 1546-1554
Author(s):  
Donato Cancellara ◽  
Fabio de Angelis ◽  
Mario Pasquino
Keyword(s):  
Strain Hardening ◽  
Seismic Response ◽  
Base Isolation ◽  
Cyclic Behavior ◽  
Hysteretic Model ◽  
Isolation System ◽  
Limit Value ◽  
Hardening Effect ◽  
Base Isolation System ◽  
Rubber Bearings

In this paper we have analyzed the influence of the strain hardening behavior of High Damping Rubber Bearings (HDRBs) adopted for a base isolation system of a Reinforced Concrete (RC) isolated structure. For the modeling of the rubber isolators we have adopted an evolution of the Bouc-Wen’s hysteretic model taking into account the incremental hardening effect which appears when the shear strain of the HDRB exceeds the limit value around 100% usually adopted in design practice. The incremental hardening effect is sometimes neglected in the design but it is an important aspect because it ensures a seismic protection of the base isolated structure also in presence of exceptional seismic events for intensity or frequency content. In this paper we have highlighted the significant influence of this phenomenon in the seismic response of the isolated structure by reporting the cyclic behavior of a HDRB respectively neglecting and considering this aspect.

Design of Base Isolation System for Buildings

2018 ◽  
pp. 67-82
Author(s):  
Govardhan Bhatt ◽  
D. K. Paul ◽  
Shubhankar Bhowmick
Keyword(s):  
Deformation Behavior ◽  
Base Isolation ◽  
Bilinear System ◽  
Isolation System ◽  
Structural Support ◽  
Protection Systems ◽  
Lead Rubber Bearings ◽  
Base Isolation System ◽  
Rubber Bearings ◽  
Seismic Base Isolation

Seismic base isolation is one of the most widely implemented and accepted seismic protection systems and is a relatively recent and evolving technology. The most common isolation system used is Laminated Lead Rubber Bearings (LLRB). They combine the function of isolation and energy dissipation in a single compact unit, giving structural support, horizontal flexibility, damping, and a re-centering force in a single unit. The force deformation behavior of LLRB is modeled as bilinear system with viscous damping. In this paper, a comprehensive design of LLRB is presented. Accurate evaluation of the structural properties and precise modeling of isolation devices are of utmost importance in predicting the response of the structure during the earthquakes. Base isolation has now been used in numerous buildings in countries like Italy, Japan, New Zealand, and USA. Base isolation is also useful for retrofitting of important buildings (like hospitals and historic buildings).

Shaking Table Test Study on Mid-Story Isolation Structures

2012 ◽  
Vol 446-449 ◽  
pp. 378-381
Author(s):  
Jian Min Jin ◽  
Ping Tan ◽  
Fu Lin Zhou ◽  
Yu Hong Ma ◽  
Chao Yong Shen
Keyword(s):  
Seismic Response ◽  
Seismic Isolation ◽  
Shaking Table Test ◽  
Base Isolation ◽  
Shaking Table ◽  
Natural Period ◽  
Isolation System ◽  
Isolation Layer ◽  
Lead Rubber Bearing ◽  
Complex Structural

Mid-story isolation structure is developing from base isolation structures. As a complex structural system, the work mechanism of base isolation structure is not entirely appropriate for mid-story isolation structure, and the prolonging of structural natural period may not be able to decrease the seismic response of substructure and superstructure simultaneously. In this paper, for a four-story steel frame model, whose prototype first natural period is about 1s without seismic isolation design, the seismic responses and isolation effectiveness of mid-story isolation system with lead rubber bearing are studied experimentally by changing the location of isolation layer. Respectively, the locations of isolation layer are set at bottom of the first story, top of the first story, top of the second story and top of the third story. The results show that mid-story isolation can reduce seismic response in general, and substructure acceleration may be amplified.

Laminated Type Isolation Device for Light Weight Structure Using Urethane Elastomer

2017 ◽  
Author(s):  
Kengo Goda ◽  
Osamu Furuya ◽  
Kohei Imamura ◽  
Kenta Ishihana
Keyword(s):  
Seismic Isolation ◽  
Base Isolation ◽  
Light Weight ◽  
Loading Test ◽  
Isolation System ◽  
Seismic Safety ◽  
Base Isolation System ◽  
Weight Structure ◽  
Isolation Device ◽  
Urethane Elastomer

At the present, base isolation system has been recognized by general earthquake resistant technique since the Great Hanshin Earthquake 1995. The seismic isolation will be aggressively applied to not only architectural and civil structures but also various structures, because the effectiveness on seismic safety had been demonstrated again in the Great East Japan Earthquake. In generally, although the base isolation system is divided into laminated rubber bearing type and friction sliding bearing type. In the case of former type, shape factor, maximum or minimum outer shapes and so on are restricted by the material characteristics in visco-elastic material. In general, the isolation structure is used in high damping rubber. However, we pay attention to base isolation using urethane elastomer. Urethane elastomer has excellent elasticity, mechanical strength, abrasion resistance, weather resistance, oil resistance, impact resistance the absorbent, anti-vibration and excellent low-temperature properties. Furthermore, it is possible to impart various characteristics by a combination of isocyanate and polyol and chain extender, requires no large-scale apparatus, it has the advantage molecular design is easy. In previous study, the research and development of laminated type base isolation device using urethane elastomer was carried out to upgrade a seismic safety for various structures. The fundamental characteristics was investigated from several loading test by using various experimental devices, and the design formula for the stiffness and equivalent damping coefficient is formulated as an approximate expression of mechanical characteristics until now. It was confirmed that urethane elastomer is not hardening up to 500% shear strain. Moreover, the experimental examination for aged deterioration in the urethane material has been continuously carried out. As the results, it was confirmed that the laminated type seismic isolation device using urethane elastomer is possible to develop as a practicable device from the stable mechanical properties as considering in design step. In this study, the small-scale laminated type base isolation device using urethane elastomer is advanced to the direction of further technical upgrading and of scale down for light-weight structure as a sever rack. The first stage, basic properties of the urethane elastomer has been investigated by loading test. Furthermore, the design equation is created by loading test using urethane elastomer. The validity of the design equation has been confirmed. The second stage, the compression creep test with laminated type base isolation device has been investigated to confirm an effect on light-weight mechanical devices.

scholarly journals STRUCTURAL DESIGN OF HIGH-RISE BUILDING WITH BASE ISOLATION SYSTEM USING ELASTIC SLIDING BEARINGS AND RUBBER BEARINGS

2001 ◽  
Vol 7 (12) ◽  
pp. 99-104 ◽  
Author(s):  
Ichizo KAWABATA ◽  
Masaharu TAKAYAMA ◽  
Yasuhiro NISHIKAWA ◽  
Yuichi KIMURA ◽  
Eiichi YAMAZAKI ◽  
...  
Keyword(s):  
Structural Design ◽  
Base Isolation ◽  
Sliding Bearings ◽  
Isolation System ◽  
High Rise ◽  
High Rise Building ◽  
Base Isolation System ◽  
Rubber Bearings

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.

Reduction of Seismic Response of Mechanical System by Base Isolation System With Friction Bearing

2007 ◽  
Author(s):  
Shigeru Aoki ◽  
Yuji Nakanishi ◽  
Kazutoshi Tominaga ◽  
Takeshi Otaka ◽  
Tadashi Nishimura ◽  
...  
Keyword(s):  
Mechanical System ◽  
Seismic Response ◽  
Base Isolation ◽  
Low Frequency ◽  
Simulation Method ◽  
Shaking Table ◽  
Restoring Force ◽  
Isolation System ◽  
Friction Bearing ◽  
Base Isolation System

Reduction of seismic response of mechanical system is important problem for aseismic design. Some types of base isolation systems are developed and used in actual base of buildings and floors in buildings for reduction of seismic response of mechanincal system. In this paper, a base isolation system utilizing bearing with friction and restoring force of bearing is proposed. Friction bearing consists of two plates having spherical concaves and oval type metal or spherical metal with rubber. First, effectiveness of the base isolation system is examined experimentally. Using artificial time histories, the isolated table is shaken on the shaking table. The maximum value of response is reduced and sum of squares of response is significantly reduced. Power spectrum is significantly reduced in almost of all frequency regions, except for very low frequency region. Next, in order to examine reduction of seismic response of actual mechanical system, a console rack is set on the isolated plate. Seismic response is also significantly reduced. Finally, obtained results of experiment are examined by simulation method. An analytical model considering friction and restoring force is used. From simulation method, effectiveness of the proposed base isolation system is demonstrated.

scholarly journals Research on Seismic Response of Base-Isolated Nuclear Island Building considering FSI Effect of PCS Water Tank

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Chenning Song ◽  
Chao Wei ◽  
Zhi Zhang
Keyword(s):  
Seismic Response ◽  
Base Isolation ◽  
Numerical Models ◽  
Horizontal Displacement ◽  
Reduction Ratio ◽  
Isolation Effect ◽  
Water Tank ◽  
Isolation System ◽  
Base Isolation System ◽  
Natural Frequency Analysis

Base isolation can be used to reduce seismic response of structure and protect the structure from damage subjected to earthquake. To study the isolation effect of new PWR nuclear power plant with a base isolation system, considering FSI (fluid-structure interaction) effect by the simplified model, two 3D numerical models (one nonisolated model and one isolated model) were established. After natural frequency analysis, one artificial ground motion was chosen to analyze isolation effect qualitatively. Based on the results, the accelerations and relative displacements of nuclear island building under ten natural ground motions were statistically analyzed to evaluate the isolation effect quantitatively. The results show that the base isolation system can reduce the natural frequencies of nuclear island building. Horizontal accelerations can be reduced effectively, but the isolation effect is not obvious in vertical direction. The acceleration reduction ratio of the top is about 70%–90%, and the acceleration reduction ratio of the lower part is about 20%–60%. Horizontal displacement of the isolated model is far larger than that of the nonisolated model, and horizontal displacement will become larger considering FSI effect. These conclusions could provide some references for studies on the isolation system of nuclear island building.

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