Theoretical and experimental analysis of an electromagnetic seismic isolation system

This paper describes three-dimensional isolation performance of seismic isolation system using air bearings. Long period seismic waves having predominant period of from a few seconds to a few ten seconds have recently been observed in various earthquakes. Also resonances of high-rise buildings and sloshing of petroleum tanks in consequence of long period seismic waves have been reported. Therefore the isolation systems having very long natural period or no natural period are required. In a previous paper [1], we proposed an isolation system having no natural period by using air bearings. Additionally we have already reported an introduction of the system, and have investigated horizontal motion during earthquake in the previous paper. It was confirmed by horizontal vibration experiment and simulation in the previous paper that the proposed system had good performance of isolation. However vertical motion should be investigated, because vertical motion varies horizontal frictional force. Therefore this paper describes investigation regarding vertical motion of the proposed system by experiment. At first, a vertical excitation test of the system is carried out so as to investigate vertical dynamic property. Then a three-dimensional vibration test using seismic waves is carried out so as to investigate performance of isolation against three-dimensional seismic waves.

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Dynamic Characteristics of the Bouc–Wen Nonlinear Isolation System

Applied Sciences ◽

10.3390/app11136106 ◽

2021 ◽

Vol 11 (13) ◽

pp. 6106

Author(s):

Zhiying Zhang ◽

Xin Tian ◽

Xin Ge

Keyword(s):

Dynamic Characteristics ◽

Seismic Isolation ◽

Influence Factors ◽

Harmonic Balance Method ◽

Control Parameters ◽

Hysteretic Model ◽

Incremental Harmonic Balance Method ◽

Isolation System ◽

Nonlinear Dynamic Characteristics ◽

Incremental Harmonic Balance

The Bouc–Wen nonlinear hysteretic model has many control parameters, which has been widely used in the field of seismic isolation. The isolation layer is the most important part of the isolation system, which can be effectively simulated by the Bouc–Wen model, and the isolation system can reflect different dynamic characteristics under different control parameters. Therefore, this paper mainly studies and analyzes the nonlinear dynamic characteristics of the isolation system under different influence factors based on the incremental harmonic balance method, which can provide the basis for the dynamic design of the isolation system.

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Vulnerability-Based Design of Sliding Concave Bearings for the Seismic Isolation of Steel Storage Tanks

Volume 8: Seismic Engineering ◽

10.1115/pvp2016-63101 ◽

2016 ◽

Author(s):

Hoang Nam Phan ◽

Fabrizio Paolacci ◽

Silvia Alessandri ◽

Phuong Hoa Hoang

Keyword(s):

Liquid Steel ◽

Seismic Isolation ◽

Failure Modes ◽

Fragility Curves ◽

Time History ◽

Probability Of Failure ◽

Design Parameters ◽

Economic Losses ◽

Storage Tanks ◽

Isolation System

Liquid steel storage tanks are strategic structures for industrial facilities and have been widely used both in nuclear and non-nuclear power plants. Typical damage to tanks occurred during past earthquakes such as cracking at the bottom plate, elastic or elastoplastic buckling of the tank wall, failure of the ground anchorage system, and sloshing damage around the roof, etc. Due to their potential and substantial economic losses as well as environmental hazards, implementations of seismic isolation and energy dissipation systems have been recently extended to liquid storage tanks. Although the benefits of seismic isolation systems have been well known in reducing seismic demands of tanks; however, these benefits have been rarely investigated in literature in terms of reduction in the probability of failure. In this paper, A vulnerability-based design approach of a sliding concave bearing system for an existing elevated liquid steel storage tank is presented by evaluating the probability of exceeding specific limit states. Firstly, nonlinear time history analyses of a three-dimensional stick model for the examined case study are performed using a set of ground motion records. Fragility curves of different failure modes of the tank are then obtained by the well-known cloud method. In the following, a seismic isolation system based on concave sliding bearings is proposed. The effectiveness of the isolation system in mitigating the seismic response of the tank is investigated by means of fragility curves. Finally, an optimization of design parameters for sliding concave bearings is determined based on the reduction of the tank vulnerability or the probability of failure.

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Development and Modeling of a Highly-Adjustable Base Isolator Utilizing Magnetorheological Elastomer

Volume 1: Development and Characterization of Multifunctional Materials; Modeling, Simulation and Control of Adaptive Systems; Integrated System Design and Implementation ◽

10.1115/smasis2013-3037 ◽

2013 ◽

Cited By ~ 3

Author(s):

Yancheng Li ◽

Jianchun Li

Keyword(s):

Analytical Model ◽

Seismic Isolation ◽

Large Scale ◽

Lateral Stiffness ◽

Magnetorheological Elastomer ◽

Isolation System ◽

Vertical Loading ◽

Base Isolator ◽

Field Dependent ◽

Dependent Property

This paper presents a recent research breakthrough on the development of a novel adaptive seismic isolation system as the quest for seismic protection for civil structures, utilizing the field-dependent property of the magnetorheological elastomer (MRE). A highly-adjustable MRE base isolator was developed as the key element to form smart seismic isolation system. The novel isolator contains unique laminated structure of steel and MRE layers, which enable its large-scale civil engineering applications, and a solenoid to provide sufficient and uniform magnetic field for energizing the field-dependent property of MR elastomers. With the controllable shear modulus/damping of the MR elastomer, the developed adaptive base isolator possesses a controllable lateral stiffness while maintaining adequate vertical loading capacity. Experimental results show that the prototypical MRE base isolator provides amazing increase of lateral stiffness up to 1630%. Such range of increase of the controllable stiffness of the base isolator makes it highly practical for developing new adaptive base isolation system utilizing either semi-active or smart passive controls. To facilitate the structural control development using the adaptive MRE base isolator, an analytical model was developed to stimulate its behaviors. Comparison between the analytical model and experimental data proves the effectiveness of such model in reproducing the behavior of MRE base isolator, including the observed strain stiffening effect.

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ULTIMATE CAPACITY OF NATURAL RUBBER BEARINGS USED IN SEISMIC ISOLATION SYSTEM

AIJ Journal of Technology and Design ◽

10.3130/aijt.1.160 ◽

1995 ◽

Vol 1 (1) ◽

pp. 160-165 ◽

Cited By ~ 8

Author(s):

Mineo TAKAYAMA

Keyword(s):

Natural Rubber ◽

Seismic Isolation ◽

Ultimate Capacity ◽

Isolation System ◽

Rubber Bearings

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Shaking Table Test Study on Mid-Story Isolation Structures

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.446-449.378 ◽

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.

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Laminated Type Isolation Device for Light Weight Structure Using Urethane Elastomer

Volume 8: Seismic Engineering ◽

10.1115/pvp2017-66167 ◽

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.

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Geotechnical Seismic Isolation System - Experimental Study

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.163-167.4449 ◽

2010 ◽

Vol 163-167 ◽

pp. 4449-4453

Author(s):

Wei Xiong ◽

Hing Ho Tsang ◽

S.H. Lo ◽

Shou Ping Shang ◽

Hai Dong Wang ◽

...

Keyword(s):

Seismic Isolation ◽

Dynamic Performance ◽

Testing Procedure ◽

Shaking Table ◽

Isolation System ◽

Isolation Technique ◽

Sand Mixture ◽

Seismic Hazard Mitigation ◽

Constituent Material ◽

Different Levels

In this study, an experimental investigation program on a newly proposed seismic isolation technique, namely “Geotechnical Seismic Isolation (GSI) system”, is conducted with an aim of simulating its dynamic performance during earthquakes. The testing procedure is three-fold: (1) A series of cyclic simple shear tests is conducted on the key constituent material of the proposed GSI system, i.e., rubber-sand mixture (RSM) in order to understand its behavior under cyclic loadings. (2) The GSI system is then subjected to a series of shaking table tests with different levels of input ground shakings. (3) By varying the controlling parameters such as percentage of rubber in RSM, thickness of RSM layer, coupled with the weight of superstructure, a comprehensive parametric study is performed. This experimental survey demonstrates the excellent performance of the GSI system for potential seismic hazard mitigation.

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