scholarly journals A method for the determination of rational characteristics of bilinear restoring force of bridge bearings for seismic isolation.

1993 ◽  
pp. 117-126 ◽  
Author(s):  
Katsushi IJIMA ◽  
Shigeo GOTO ◽  
Tadaharu WADA
Keyword(s):  
Seismic Isolation ◽  
Restoring Force ◽  
Bridge Bearings

Sliding Isolation System for Bridges: Experimental Study

1992 ◽  
Vol 8 (3) ◽  
pp. 321-344 ◽  
Author(s):  
M. C. Constantinou ◽  
Allaoua Kartoum ◽  
A. M. Reinhorn ◽  
Paul Bradford
Keyword(s):  
Seismic Isolation ◽  
Earthquake Excitation ◽  
Restoring Force ◽  
Additional Energy ◽  
Isolation System ◽  
Sliding Isolation ◽  
Wide Range ◽  
Energy Dissipation Capacity ◽  
Bridge Bearings ◽  
Good Agreement

A seismic isolation system for bridges has been tested on a shake table. The system consisted of Teflon disc bridge bearings and displacement control devices. These devices provided restoring force for re-centering the bridge during earthquake excitation, additional energy dissipation capacity and rigidity for service loading. The tests were carried out with a 51-kip model which was subjected to strong recorded earthquake motions with a wide range of frequency content and to simulated motions compatible with CalTrans 0.6g design spectra. In all tests the isolated deck responded with peak acceleration less than the peak table acceleration and peak bearing displacement less than the peak table displacement. Results from an analytical model show very good agreement with experimental results.

Research and Development of Earthquake Isolation System Using Vertically Utilized Coiled Spring

2006 ◽  
Author(s):  
Tsuyoshi Fukasawa ◽  
Satoshi Fujita
Keyword(s):  
Research And Development ◽  
Seismic Isolation ◽  
Scale Model ◽  
Force Characteristic ◽  
Light Weight ◽  
Restoring Force ◽  
Isolation System ◽  
Coiled Spring ◽  
Isolation Performance ◽  
Weight Structures

This paper describes the research and development of new type of the isolation systems suitable for various structures. Basic concept of the new isolation system is to realize cost effective design without any reduction in the isolation performance. This paper presents results obtained from experimental and analytical studies to evaluate isolation performances of newly developed the isolation system. In the experiment, static tests were first carried out using a 0.20 scale model (55 kg mass, and 0.50 m × 0.50 m × 0.27 m size) for isolated-light-weight-structures model which was supported by two linear ball bearings and, restoring force was provided to superstructure by transversal stiffness of a coiled spring, so as to examine restoring force characteristic of the coiled spring. Second, dynamic tests were implemented in order to investigate the isolation performance of the isolation system against several actual seismic inputs. In analysis, seismic response analyses for the scale model, regarding the vibration tests using the actual seismic wave, were carried out to evaluate the response analytical method for the isolation system using the coiled spring. From these results, the followings are clarified. (1) Analytical results for the isolated light-weight-structures model agree well with experiment results. (2) The newly developed seismic isolation system using the coiled spring reduced response accelerations of the light-weight-structures sufficiently.

Shaking Table Tests With Large Test Specimens of Seismically Isolated FBR Plants: Part 2—Damage Test of Reinforced Concrete Wall Structure

2009 ◽  
Author(s):  
Satoru Inaba ◽  
Takuya Anabuki ◽  
Kazutaka Shirai ◽  
Shuichi Yabana ◽  
Seiji Kitamura
Keyword(s):  
Reinforced Concrete ◽  
Seismic Isolation ◽  
Shaking Table Test ◽  
Shaking Table ◽  
Wall Structure ◽  
Shaking Table Tests ◽  
Concrete Wall ◽  
Restoring Force ◽  
Seismically Isolated ◽  
Rubber Bearings

This paper describes the dynamic damage test of a reinforced concrete (RC) wall structure with seismic isolation sysytem. It has been expected that seismically isolated structures are damaged in sudden when the accelerations of the structures exceed a certain level by hardening of the rubber bearings. However, the response behavior and the damage mode have not been observed by experimental test yet. So, shaking table tests were carried out at “E-Defense”, equipping the world’s largest shaking table, located at Miki City, Hyogo prefecture, Japan. The specimen was composed of an upper structure of 600 ton by weight and six lead-rubber bearings (LRBs) of 505 mm in diameter which provide both stiffness and hysteretic damping. The upper structure consisted of a RC mass and four RC walls with counter weight. The RC wall structure was designed so that the damage of the RC wall occurred between the shear force at the hardening of the rubber bearings and that at their breaking. The dimensions of the RC wall were 1600 × 800 × 100 mm (B × H × t). The reinforcement ratios were 2.46% in vertical by D13 (deformed reinforcing bar, 13 mm in diameter) and 1.0% in horizontal by D10. The shaking table test was conducted consecutively by increasing the levels up to 225% of tentative design earthquake motion. Consequently, because of the increase of the structural response by the hardening of the rubber bearings, the damage of the wall structure with seismic isolation system suddenly happened. In addition, the preliminary finite element analysis simulated the test results fairly well, which were the restoring force characteristics, the crack patterns of the RC wall structure and such.

Response Analysis of a Seismic Isolated Structure Considering the Nonlinearity of the Rubber Bearings

2013 ◽  
Author(s):  
Alexandre Borsoi ◽  
Satoshi Fujita ◽  
Keisuke Minagawa
Keyword(s):  
Nuclear Power ◽  
Seismic Isolation ◽  
Power Plants ◽  
Industrial Structure ◽  
Response Analysis ◽  
Vertical Load ◽  
Restoring Force ◽  
Seismic Safety ◽  
Rubber Bearings ◽  
Seismic Isolation Systems

In Japan, the application of seismic isolation systems using rubber bearings to industrial structure and new generation Nuclear Power Plants have been considered in order to enhance seismic safety. However, the isolation performance will decline in case of huge earthquakes, because of the nonlinearity of both horizontal and vertical restoring characteristics of the rubber bearings. The horizontal restoring force has a hardening characteristic and the vertical restoring force has a softening characteristic. In addition, the horizontal nonlinearity depends on vertical load, so the interaction between the horizontal and vertical response is important. Consequently, in this paper, the analysis of the nonlinearity of the rubber bearings and the coupling between those two directions will be carried out. Then, after comparing these two approaches, the utility of considering this dependency will be estimated. To do so, a simulation program, based on the Runge-Kutta-Gill’s method has been developed in order to evaluate the seismic response of the isolated structure composed of rubber bearings and oil dampers. The nonlinearity of the rubber bearings is considered, and the coupling of the vertical load and the horizontal hardening has been implemented.

DEVELOPMENT AND APPLICATION OF ISOLATION BEARING ELEMENT CONSIDERING BI-DIRECATIONAL COUPLED INTERACTION

2020 ◽  
Vol 7 (2) ◽  
Author(s):  
Shen Zhang ◽  
Baiqing Zhang ◽  
Ming Cheng
Keyword(s):  
Seismic Isolation ◽  
Base Isolation ◽  
Seismic Analysis ◽  
Vertical Direction ◽  
Seismic Energy ◽  
Force Model ◽  
Reinforced Concrete Structure ◽  
Restoring Force ◽  
Lateral Direction ◽  
Bearing Element

Base isolation technology, which introduces isolated bearings between the top of foundation and upper structure, is regarded as an effective method to reduce seismic energy absorbed by the upper structure. Lead rubber bearing (LRB), that is, a representative seismic isolation device, has been widely used in isolated structural systems. An isolation bearing element for simulating the behavior of LRB was developed with the user element subroutine (UEL) feature of ABAQUS, which was further introduced into seismic analysis of the base-isolated structure with LRB. The Bouc-Wen bi-directional coupled restoring force model was adopted in the developed element to describe the nonlinear hysteric characteristics for LRB in the lateral direction. Meanwhile, the strength differences of LRB in the vertical direction were also included in the element. The accuracy of the isolation bearing element was verified by close agreement between numerically predicted hysteresis curves and experimental counterparts. Moreover, the nonlinear earthquake responses of a four-story reinforced concrete structure isolated by LRB with and without the bi-directional coupled interaction of bearing restoring forces were separately explored, and it was revealed that the bi-directional coupled interaction had considerable effects on the seismic responses of the isolated buildings. Once these coupled interaction effects were not taken into account, the displacement of LRB was underestimated while the bearing capacity would be over-predicted, which had a detrimental effect on the design of isolated buildings.

Influence of Mullins and hardening effects of seismic isolation rubber bearings on the seismic response

2021 ◽  
Author(s):  
Hiroshi Shimmyo ◽  
Tolga Onal ◽  
Shozo Nakamura ◽  
Kazuya Tokunaga
Keyword(s):  
Seismic Response ◽  
Seismic Isolation ◽  
Hysteresis Loops ◽  
Highway Bridges ◽  
Restoring Force ◽  
Two Factors ◽  
Product Test ◽  
Rubber Bearings ◽  
Isolated Bridges ◽  
Force Displacement

<p>In the current Specifications for Highway Bridges of the Japan Road Association, a bilinear force- displacement relationship is recommended as the hysteresis loops of the seismic isolation rubber bearings for the dynamic structural analysis of seismically isolated bridges. However, it has been confirmed that the restoring force characteristics of the actual devices are different from the bilinear model due to the Mullins effect and the hardening phenomenon of the rubber under large shear strains. In this study, the effect of these two factors on the seismic response of a bridge is investigated through the dynamic analysis with the tri-linear double target model considering the factors. The parameters of the model are obtained from product test results of lead-plugged laminated rubber bearings and high-damping laminated rubber bearings.</p>

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