Experimental investigations of a rolling-based seismic isolation system

2016 ◽  
Vol 24 (2) ◽  
pp. 323-342 ◽  
Author(s):  
Mohammed Ismail ◽  
Jośe Rodellar
Keyword(s):  
Seismic Isolation ◽  
Construction Materials ◽  
Shear Stiffness ◽  
Experimental Tests ◽  
Horizontal Displacement ◽  
Shear Loading ◽  
Experimental Investigations ◽  
Loading Frequency ◽  
Isolation System ◽  
Test Parameters

This paper presents the results of an extensive series of experimental tests to identify the mechanical characteristics of a recently-proposed seismic isolation device known as the Roll- In-Cage (RNC) isolator. Several 1/10 reduced-scale experimental prototypes are examined considering different configurations, characteristics and construction materials. Cyclic horizontal displacement tests, varying the test parameters of shear displacement amplitude, axial load, and loading frequency are performed. The RNC isolator’s force-displacement relationship, shear stiffness and damping properties are investigated in terms of different test parameters. In addition, vertical cyclic displacement is applied to examine the RNC isolator’s capability to withstand vertical axial tension. Furthermore, tests at the ultimate-level consisting of an increasing monotonic shear loading beyond the bearing’s design displacement are also carried out to investigate its behavior after activating its self-stopping or buffer mechanism. Some experimentally obtained results are verified using numerical simulation models. A comparative analysis of the results is then performed to allow for highlighting the main features of the RNC isolator.

scholarly journals A liquid spring–magnetorheological damper system under combined axial and shear loading for three-dimensional seismic isolation of structures

2018 ◽  
Vol 29 (18) ◽  
pp. 3517-3532 ◽  
Author(s):  
Sevki Cesmeci ◽  
Faramarz Gordaninejad ◽  
Keri L Ryan ◽  
Walaa Eltahawy
Keyword(s):  
Seismic Isolation ◽  
Theoretical Calculations ◽  
Three Dimensional ◽  
Real Life ◽  
Vertical Component ◽  
Axial Loading ◽  
Shear Loading ◽  
Magnetorheological Damper ◽  
Isolation System ◽  
Fail Safe

This study focuses on experimental investigation of a fail-safe, bi-linear, liquid spring magnetorheological damper system for a three-dimensional earthquake isolation system. The device combines the controllable magnetorheological damping, fail-safe viscous damping, and liquid spring features in a single unit serving as the vertical component of a building isolation system. The bi-linear liquid spring feature provides two different stiffnesses in compression and rebound modes. The higher stiffness in the rebound mode prevents a possible overturning of the structure during rocking mode. For practical application, the device is to be stacked together along with the traditional elastomeric bearings that are currently used to absorb the horizontal ground excitations. An experimental setup is designed to reflect the real-life loading conditions. The 1/4th-scale device is exposed to combined dynamic axial loading (reflecting vertical seismic excitation) and constant shear force that are up to 245 and 28 kN, respectively. The results demonstrate that the device performs successfully under the combined axial and shear loadings and compare well with the theoretical calculations.

Prestress Rubber Isolator and its Mechanical Properties

2010 ◽  
Vol 163-167 ◽  
pp. 4405-4414 ◽  
Author(s):  
Li Hua Zou ◽  
Kai Huang ◽  
Wei Zhang ◽  
Yu Rao ◽  
Li Yuan Wang
Keyword(s):  
Mechanical Properties ◽  
Seismic Isolation ◽  
Patent Application ◽  
Horizontal Displacement ◽  
Vertical Deformation ◽  
Calculation Formula ◽  
Isolation System ◽  
Chinese Patent ◽  
Flexible Cables ◽  
Rubber Isolator

A new seismic isolation system,namely the prestress rubber isolator(PRI,Chinese patent application number:200910174415x),is introduced.The basic principle of this new isolator is: making all or part of vertical deformation of isolator be finished in advance by exerting a longitudinal pre-compressional stress on the rubber isolator with flexible cables, the prestress tension cables become loose because of unloading after the exerting of superstructure loads,and the loose cables can limit the horizontal displacement and resist the tension of isolator. The calculation formula of horizontal stiffness of isolator is derivated,and the mechanical properties are researched. The research results show that:besides the horizontal isolating property of common rubber isolators,the prestress rubber isolator has also properties of reducing vertical deformation, limiting horizontal displacement and resisting tension.Moreover,the prestress isolator has also a certain vertical isolating affect because of the improve of rubber thickness.

Seismic base isolation for steel structures

1985 ◽  
Vol 12 (1) ◽  
pp. 73-81
Author(s):  
S. F. Stiemer ◽  
B. B. Barwig
Keyword(s):  
Base Isolation ◽  
Steel Structures ◽  
Experimental Tests ◽  
Shaking Table ◽  
Earthquake Ground Motion ◽  
Experimental Investigations ◽  
Steel Buildings ◽  
Earthquake Excitation ◽  
Isolation System ◽  
Base Isolation System

Base isolation is a strategy for a design of buildings in areas where seismic loads govern. It enables the reduction of earthquake excitation to an acceptable level, without an increase of structural acceleration. This paper presents the results of the experimental investigations of various schemes of first-storey designs for steel buildings with base isolation.A scaled-down steel frame building was used for the shaking table tests, which were conducted in the Earthquake Simulator Laboratory of the University of British Columbia. The base-storey design was altered while the dynamic response of the frame was recorded. The base isolation consisted of steel roller bearings with parallel steel yield rings, to limit excessive displacements and provide wind restraint.The proposed base storey is substantially different from conventional solutions. The variation in the base-storey design was aimed at the elimination of the blind base storey or double foundation in order to increase the economy of the base-isolation system. The experimental tests showed suitable design approaches, and analytical studies to optimize them will follow.It was verified that uncoupling of buildings from the earthquake ground motion is relatively simple to achieve. Certain restraint is required to resist wind and other horizontal loads. This is usually achieved by mechanical fuses or energy absorbers. A solid state energy absorber was used in the described tests. Key words: base-isolation system for buildings, earthquake-resistant steel structures, experimental investigations, retrofit system.

Dynamic Testing and Modeling of Magneto-Rheological Elastomers

2009 ◽  
Author(s):  
Muhammad Usman ◽  
Dong-Doo Jang ◽  
In-Ho Kim ◽  
Hyung-Jo Jung ◽  
Jeong-Hoi Koo
Keyword(s):  
Magnetic Field ◽  
Dynamic Behavior ◽  
Dynamic Testing ◽  
Experimental Tests ◽  
Shear Loading ◽  
Shear Mode ◽  
Loading Frequency ◽  
Engineering Structures ◽  
Exciting Frequency ◽  
Magneto Rheological

This study presents the dynamic numerical model of magneto-rheological elastomers (MREs) along with the dynamic testing of the material under various loading conditions. Primarily the loading in shear mode is considered in this study because many civil engineering structures are subjected to shear loading. Experimental tests were carried out in order to characterize the dynamic behavior of MREs. A test setup was designed and fabricated to load the MRE samples in shear mode with varying magnetic fields. A series of shear tests of MRE samples were performed under various magnetic field values, amplitudes and frequencies of loading. The test results show that the material stiffness is increased with increasing magnetic field and loading frequency within the ranges of the magnetic field and exciting frequency considered in this work. Based on the experimental results, a dynamic model was developed to capture the dynamic behavior of the MRE.

Application of Energy Method for Determining Loss Factor in Dynamic Systems with Hysteretic Damping

2014 ◽  
Vol 580-583 ◽  
pp. 2978-2982
Author(s):  
Vladimir Smirnov ◽  
Vladimir Mondrus
Keyword(s):  
Energy Method ◽  
Loss Factor ◽  
Seismic Isolation ◽  
Vibration Isolation ◽  
Damping Ratio ◽  
Experimental Investigations ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Hysteretic Damping ◽  
Different Types

The article studies the energy method for determining loss factor due to hysteretic damping in systems of vibration and seismic isolation. Typical measure of damping is, where φ is the phase angle between stress and strain sinusoids [1], or damping constant δ ( [2, 3]). Both of these parameters are acquired through experimental investigations for each type of boundary conditions or element’s cross section. Proposed energy method is capable of loss factor ψ determination for different types of beams based on only one experimental investigation. This method is used in the paper to determine the damping ratio of elastic element in vibration isolation system of precision equipment.

Isolation Performance of Intelligent Seismic Isolation System Using Air Bearing

2009 ◽  
Author(s):  
Satoshi Fujita ◽  
Keisuke Minagawa ◽  
Mitsuru Miyazaki ◽  
Go Tanaka ◽  
Toshio Omi ◽  
...  
Keyword(s):  
Seismic Isolation ◽  
Seismic Waves ◽  
Three Dimensional ◽  
Vertical Motion ◽  
Air Bearings ◽  
Natural Period ◽  
Isolation System ◽  
Vertical Excitation ◽  
Long Period ◽  
Isolation Performance

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.

scholarly journals Dynamic Characteristics of the Bouc–Wen Nonlinear Isolation System

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.

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

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.

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

2013 ◽  
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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