Development on Rubber Bearings for Sodium-Cooled Fast Reactor: Part 1 — Examination Plan

This paper describes the past preliminary examination results and the new characteristic examination plans of the thick laminated rubber bearing for the application to Sodium-cooled Fast Reactor (SFR). The preliminary examination focusing on mechanical characteristics such as shear modulus with a 1/8-scale model (ϕ= 200 mm) and creep characteristics with a 1/13-scale model (ϕ= 120 mm) were carried out [1]. With the basic mechanical characteristic examination, the basic design formulas were temporarily confirmed. Furthermore, to establish the creep prediction formula, the creep characteristic examination has been carried out and the creep amount during the plant life has been approximately predicted. To obtain the mechanical properties of thick laminated rubber bearing with the scale-effect, the basic mechanical characteristic examination, including the ultimate behavior test, with the 1/2-scale model (ϕ= 800 mm) will be planned to confirm design margin with clarifying the ultimate limit curve under the bi-axial loading such as shear strain and the normal stress. Moreover, the deterioration promoted examination will be planned. The object of this examination is intended to grasp the degree of aging that may be caused by environmental effects during the plant life. By the accelerated deterioration examination results, the influence by aging on the mechanical characteristic and ultimate behavior of the laminated rubber bearing could be evaluated.

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Development on Rubber Bearings for Sodium-Cooled Fast Reactor: Part 3 — Ultimate Properties of a Half Scale Thick Rubber Bearings Based on Breaking Test

Volume 8: Seismic Engineering ◽

10.1115/pvp2016-63397 ◽

2016 ◽

Cited By ~ 1

Author(s):

Tsuyoshi Fukasawa ◽

Shigeki Okamura ◽

Tomohiko Yamamoto ◽

Nobuchika Kawasaki ◽

Tsutomu Hirotani ◽

...

Keyword(s):

Fast Reactor ◽

Static Loading ◽

Restoring Force ◽

Natural Period ◽

Rubber Bearing ◽

Safety Margins ◽

Ultimate Properties ◽

Loading Tests ◽

Rubber Bearings ◽

Force Characteristics

This paper describes the results of static loading tests using a half-scale thick rubber bearing to investigate ultimate properties application for a Sodium-cooled-Fast-Reactor (SFR). The thick rubber bearing, which has a rubber layer roughly three times thicker in comparison with conventional rubber bearings, has been developed by the authors to ensure seismic safety margins for components installed in the reactor building, and to reduce seismic response in the vertical direction as well as horizontal direction. The thick rubber bearings, 1600 mm in diameter at full scale, have been designed to provide a rated load of about 10000 kN with a horizontal natural period of 3.4 s and a vertical natural period of about 0.133 s. The fundamental restoring-force characteristics of the thick rubber bearings has been already cleared through the static loading tests using a half-scale thick rubber bearing, 800 mm in diameter. However, variations of the restoring force characteristics and ultimate properties have not been obtained yet. These validations are essential from the point of view of Probabilistic Risk Assessment (PRA) for a base isolated nuclear plant as well as to verify the structural integrity of the thick rubber bearing. The purpose of this paper is to indicate the variation of the stiffness and damping ratio concerning restoring force characteristics and the breaking strain or stress as ultimate properties through static loading tests using the half-scale thick rubber bearings.

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Design of Shape Memory Alloy Damper for Base Isolated Structure

Volume 1B: 16th Biennial Conference on Mechanical Vibration and Noise ◽

10.1115/detc97/vib-3824 ◽

1997 ◽

Author(s):

Krzysztof Wilde ◽

Paolo Gardoni ◽

Yozo Fujino ◽

Stefano Besseghini

Keyword(s):

Shape Memory Alloy ◽

Shape Memory ◽

Base Isolation ◽

Hysteretic Behavior ◽

Isolation System ◽

Rubber Bearing ◽

Laminated Rubber Bearing ◽

Base Isolation System ◽

Rubber Bearings ◽

Smart Base Isolation

Abstract Base isolation provides a very effective passive method of protecting the structure from the hazards of earthquakes. The proposed isolation system combines the laminated rubber bearing with the device made of shape memory alloy (SMA). The smart base isolation uses hysteretic behavior of SMA to increase the structural damping of the structure and utilizes the different responses of the SMA at different levels of strain to control the displacements of the base isolation system at various excitation levels. The performance of the smart base isolation is compared with the performance of isolation by laminated rubber bearings to assess the benefits of additional SMA damper for isolation of three story building.

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Development on Rubber Bearings for Sodium-Cooled Fast Reactor: Part 4 — Aging Properties of a Half Scale Thick Rubber Bearings Based on Breaking Test

Volume 8: Seismic Engineering ◽

10.1115/pvp2016-63105 ◽

2016 ◽

Author(s):

Tomoyoshi Watakabe ◽

Tomohiko Yamamoto ◽

Tsuyoshi Fukasawa ◽

Shigeki Okamura ◽

Takahiro Somaki ◽

...

Keyword(s):

Mechanical Properties ◽

Fast Reactor ◽

Seismic Isolation ◽

Hysteresis Loops ◽

Natural Period ◽

Isolation System ◽

Rubber Bearing ◽

Aging Properties ◽

Rubber Bearings ◽

Effects Of Aging

A seismic isolation system composed of a thick rubber bearing and an oil damper has been developed for Sodium-Cooled Fast Reactor. One of the advantages of the isolation system is the use of thick rubber bearings to ensure the longer vertical natural period of a plant, thereby mitigating seismic loads to mechanical components. Based on many previous studies, rubber bearing technology has progressed, but test data regarding the effect of aging is not sufficient. Moreover, there is no data on the limits of linear strain and breaking behavior for thick rubber bearings after aging. This paper focused on the aging properties of thick rubber bearings, such as basic mechanical properties and ultimate strength. An aging test of thick rubber bearings was conducted using 1/2-scale (800mm diameter) and 1/8-scale (200mm diameter) rubber bearings. Aging of the rubber bearings was reproduced using thermal degradation, in which the target of aging periods were 30 and 60 years. The hysteresis loops of the thick rubber bearings after aging were obtained through horizontal and vertical static loading tests, and the effects of aging were evaluated by comparison with the initial mechanical properties. In addition, for the purpose of further research, the effect of scale by aging was clarified to compare the mechanical properties between the 1/2-scale and 1/8-scale rubber bearings.

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Evaluation of Seismic Performance Focusing on Increasing Response of Lead Rubber Bearing (LRB) and Over Strength of RC Pier During Earthquake

Global Journal of Researches in Engineering ◽

10.34257/gjreevol20is3pg33 ◽

2020 ◽

pp. 33-50

Author(s):

Naito Nobuyuki ◽

Park Kyeonghoon ◽

Mazda Taiji ◽

Uno Hiroshige ◽

Kawakami Masahide

Keyword(s):

Shear Strain ◽

Seismic Performance ◽

Elastic Behavior ◽

Rubber Bearing ◽

Lead Rubber Bearing ◽

Lead Rubber Bearings ◽

Laminated Rubber Bearing ◽

Current Design ◽

Rubber Bearings ◽

Bearing Behavior

The characteristics of the seismic bearing change depending on various factors. When an earthquake occurs, the behavior of the bridge may differ from the values expected in the structural design. The shear deformation of the seismic bearing may increase, but it is difficult to reach the fracturede formation. This paper studied the effect of the stiffness due to various dependency and durability on Lead Rubber Bearings (LRB) and the over strength of bridge piers on the bearing behavior when an earthquake occurred. As a result, if the stiffness of LRB reduces within the criteria, seismic performance can be expected safety even if the shear strain designed in the current design is greater than the allowable shear strain. The reason is that the hardening phenomenon in the high strain region of the laminated rubber bearing suppresses the displacement. Also, since the seismic bridges with over strength of the piers have come near elastic behavior when an earthquake occurs, shear strain is easy to be large.

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Research and Development of Three-Dimensional Isolation System for Sodium-Cooled Fast Reactor: Part 3 — Characteristics for Elements on Basis of Half-Scale Loading Tests

Volume 8: Seismic Engineering ◽

10.1115/pvp2019-93475 ◽

2019 ◽

Author(s):

Takahiro Somaki ◽

Tsuyoshi Fukasawa ◽

Shigeki Okamura ◽

Takayuki Miyagawa ◽

Masato Uchita ◽

...

Keyword(s):

Fast Reactor ◽

Seismic Isolation ◽

Design Method ◽

Three Dimensional ◽

Isolation System ◽

Rubber Bearing ◽

In Series ◽

Loading Tests ◽

Rubber Bearings ◽

Disc Spring

Abstract The authors have been developing the three-dimensional isolation system for a Sodium-cooled Fast Reactor, and reported the details of characteristics of disc springs and vertical oil dampers on the basis of full-scale loading tests [1]. To clarify the fundamental characteristics of the three-dimensional isolation system, the loading tests using a half-scale assembled specimen have been planned, which is composed of a rubber bearing, disc spring units, the horizontal supporting functions, the smoothly sliding elements, and the rotate restraint elements. This paper describes each characteristic of the rubber bearings, disc springs and sliding element before assembling a half-scale specimen of the three-dimensional seismic isolation system by the static or dynamic loading. The applicability of design method, the scaling effect in disc springs, and the dependence on the friction coefficient of the sliding elements were investigated and confirmed. Additionally, the method of minimizing the variation of force-displacement relationships between four disc spring units, each of which has the three disc springs stacked in parallel and six disc springs stacked in series, was studied. It should be noted that this paper is in series from Part 2 [1] held on 2018PVP.

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Research and Development of Three-Dimensional Isolation System for Sodium-Cooled Fast Reactor: Part 5 — Isolation Performance Applied to Reactor Building

Volume 9: Seismic Engineering ◽

10.1115/pvp2020-21709 ◽

2020 ◽

Author(s):

Takahiro Somaki ◽

Tsuyoshi Fukasawa ◽

Shigeki Okamura ◽

Takayuki Miyagawa ◽

Masato Uchita ◽

...

Keyword(s):

Fast Reactor ◽

Analytical Modeling ◽

Three Dimensional ◽

Response Spectra ◽

Scale Model ◽

Isolation System ◽

Rubber Bearing ◽

Reactor Building ◽

Isolation Performance ◽

Disc Spring

Abstract This paper presents the isolation performance of a three-dimensional base isolated Sodium-cooled Fast Reactor building. The three-dimensional isolation system consists of rubber bearing with the horizontal oil damper for the horizontal isolation system and disc spring units with vertical oil dampers for the vertical one, where the vertical one is set under the horizontal one to be arranged in series. These elements excepting the horizontal oil damper have been developed for the three-dimensional isolation system through the static or the dynamic loading tests using a full scale or a half scale model. Regarding the horizontal oil damper which is necessary for the three-dimensional isolation system as well as the horizontal isolation system, the details would be described in Part 6. The authors also have been tackled to create the analytical modeling for each element such as the disc spring units, vertical oil damper and rubber bearing. The previous studies from part 1 to part 4 clarified that the newly analytical model, each of which is defined by the differential equations, could accurately express relationships between the force and displacement of each element. To demonstrate the reduction effect (performance) of the seismic responses for the three-dimensional isolation system, the seismic response analyses using newly analytical modeling were performed for the Sodium-cooled Fast Reactor building that is modeled into the multi-degree-of-freedom-system. The isolation performance of the three-dimensional isolation system is verified through the floor response spectra evaluated at the position where the primary components are placed, in comparison with those by the conventional 2D horizontally isolation system using the rubber bearing without the vertical elements.

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Tri-Camera High-Speed Videogrammetry for Three-Dimensional Measurement of Laminated Rubber Bearings Based on the Large-Scale Shaking Table

Remote Sensing ◽

10.3390/rs10121902 ◽

2018 ◽

Vol 10 (12) ◽

pp. 1902 ◽

Cited By ~ 2

Author(s):

Xiaohua Tong ◽

Kuifeng Luan ◽

Xianglei Liu ◽

Shijie Liu ◽

Peng Chen ◽

...

Keyword(s):

High Speed ◽

Large Scale ◽

Three Dimensional ◽

Image Sequences ◽

Bundle Adjustment ◽

Shaking Table ◽

Camera Image ◽

Rubber Bearing ◽

Laminated Rubber Bearing ◽

Rubber Bearings

Laminated rubber bearings are widely used for the mitigation of seismic damage of large-scale structures and equipment. However, owing to the flexibility in horizontal direction, the traditional contacted transducer is difficult to acquire the displacement data accurately in the three directions, respectively. In this paper, three-dimensional displacement measurement of laminated rubber bearing based on the large-scale shaking table is achieved by the use of a tri-camera high-speed videogrammetric system consisting of three complementary-metal-oxide-semiconductor (CMOS) cameras, one synchronous controller, and one pair of 1000 watt light sources, which are used to simultaneously acquire the tri-camera image sequences of laminated rubber bearing at a speed of 300 frames per second (fps). Firstly, this paper proposes a fast image block technique for detecting and tracking targets in tri-camera image sequences by integration of techniques morphological edge detection, attribute based ellipse extraction and least-squares-based fitting adjustment. Secondly, this paper presents an integrated bundle adjustment approach, which brings continuous tracking points into one collinearity condition equation, to reconstruct the three dimensional coordinates of continuous tracking points, for the purpose of improving the accuracy of three-dimensional coordinates of tracking points based on tri-camera image sequences. At last, an empirical experiment was conducted to measure the three-dimensional displacement of laminated rubber bearings on the shaking table by the use of the proposed method. The experimental results showed that the proposed method could obtain three-dimensional displacement of laminated rubber bearings with an accuracy of more than 0.5 mm.

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Development on Rubber Bearings for Sodium-Cooled Fast Reactor: Part 2 — Fundamental Characteristics of Half-Scale Rubber Bearings Based on Static Test

Volume 8: Seismic Engineering ◽

10.1115/pvp2015-45263 ◽

2015 ◽

Cited By ~ 2

Author(s):

Tsuyoshi Fukasawa ◽

Shigeki Okamura ◽

Tomohiko Yamamoto ◽

Nobuchika Kawasaki ◽

Takahiro Somaki ◽

...

Keyword(s):

Fast Reactor ◽

Static Loading ◽

Seismic Isolation ◽

Linear Strain ◽

Isolation System ◽

Rubber Bearing ◽

Strain Limit ◽

Seismic Force ◽

Loading Tests ◽

Rubber Bearings

This paper described the results of the static loading tests using a half-scale thick rubber bearing to investigate the fundamental characteristics such as horizontal and vertical restoring force of a rubber bearing applied to a Sodium-cooled-Fast-Reactor (SFR). Since the SFR has thin-walled component structures, a seismic isolation system is employed to mitigate the seismic force. A rubber bearing with thick rubber layers is used for the seismic isolation system applied to the SFR, it was developed aiming for isolation of not only horizontal response acceleration, but also vertical response acceleration. The thick rubber bearing of 1600 mm in diameter full-scale was designed to provide about a 10000 kN rated load with a horizontal natural period of 3.4 s and a vertical one of 0.125 s. Moreover, a linear strain limit of the thick rubber bearing was designed to accept a horizontal displacement of 700 mm or more in order to ensure a double safety margin for response displacements against a design basis ground motion. The static loading tests were performed using a half-scale thick rubber bearing with a diameter of 800 mm to investigate the horizontal/vertical stiffness, damping ratio, a linear strain limit in horizontal direction and a tensile yield stress in the vertical direction. The fundamental characteristic of rubber bearings employed to the SFR and the validity of a design formula became clear through the static loading tests.

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Restoring Force Characteristics of Laminated Rubber Bearings Under Various Restraining Conditions

Journal of Pressure Vessel Technology ◽

10.1115/1.1637643 ◽

2004 ◽

Vol 126 (1) ◽

pp. 141-147

Author(s):

Nobuo Masaki ◽

Shigenobu Suzuki

Keyword(s):

Bending Moment ◽

Combined Loading ◽

Loading Test ◽

Restoring Force ◽

Shape Factors ◽

Rubber Bearing ◽

Laminated Rubber Bearing ◽

Degree Of Restraint ◽

Rubber Bearings ◽

Force Characteristics

We conducted the measurement of restoring force characteristics of laminated rubber bearings under various restraining conditions. In the experiment, we provided three laminated rubber bearings with various second shape factors S2=3,4,4.94. The restoring force is obtained by using a newly designed combined loading test apparatus. By using this apparatus, the laminated rubber bearing could be subjected to shear, compressive and rotational deformations independently. In this experiment, we defined the degree of restraint as the ratio of the bending moment to the restricting bending moment which was measured when the rotation angle of the laminated rubber bearing was zero radian. This means that the flanges on both sides of the laminated rubber bearings were kept parallel during horizontal deformations. From the experiment, it was confirmed that restoring force characteristics were affected by the degree of restraint. Some reduction in restoring forces was observed when the degree of restraint was small. In particular the laminated rubber bearing with a small second shape factor, namely the rubber bearing, had a slender shape, easily buckling under small horizontal displacement. It was also confirmed that bending stiffness of the laminated rubber bearing had shear strain dependency and vertical load i.e., surface pressure dependency. The results of this experiment reveal that we should consider the reduction of the restoring force if the upper or lower structure of the laminated rubber bearing is not sufficiently rigid.

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