Application of Semi-Active Oil Damper System to Base Isolation Systems

2002 ◽  
Author(s):  
Takashi Kawai ◽  
Yasuo Tsuyuki ◽  
Yutaka Inoue ◽  
Osamu Takahashi ◽  
Koji Oka
Keyword(s):  
Base Isolation ◽  
Shaking Table ◽  
The Other ◽  
Damping Coefficient ◽  
Damping Force ◽  
Mass Model ◽  
Maximum Acceleration ◽  
Rubber Bearing ◽  
Single Mass ◽  
Isolation Systems

This paper deals with one of the applications of the Semi-Active Oil Damper system, which applies base isolation systems reducing the maximum acceleration. The theory of the Semi-Active Oil Damper system is based on Karnopp Theory. The theory has been actually now in use for a Semi-active suspension system of the latest Shinkansen (New trunk lines) trains to improve passenger’s comfortable riding. Various experiments have been conducted using a single mass model whose weight is 15 ton on the shaking table. This model is supported by the rubber bearing. The natural frequency is 0.33Hz of this system. Two Semi-Active Oil Damper were installed in the model and excited the table for one horizontal direction. The maximum damping force of each Semi-Active Oil Damper used for the model is 4.21 kN. The damper can change the damping coefficient by utilizing two solenoid valves. Therefore, the dynamic characteristic of the damping force has two modes. One is a hard damping coefficient and the other is a soft one. It was confirmed that the maximum acceleration of the Semi-Active Oil Damper system can be reduced more than 20% in comparison with the passive Oil Damper system in our tests.

Study on Seismic Isolation and Hi-Frequency Vibration Isolation Technology for Equipment in Nuclear Power Plant Using Aero Floating Technique

2020 ◽  
Author(s):  
Kiyotaka Takito ◽  
Osamu Furuya ◽  
Hiroshi Kurabayashi ◽  
Kunio Sanpei
Keyword(s):  
Nuclear Power ◽  
Seismic Isolation ◽  
Vibration Isolation ◽  
Shaking Table Test ◽  
Base Isolation ◽  
Ground Surface ◽  
Shaking Table ◽  
Maximum Acceleration ◽  
Seismic Motion ◽  
Floating Base

Abstract In Japan, most structures on the ground surface need seismic countermeasures because of frequently earthquakes. On the other hand, vibration isolation devices are applied to precision or important equipment in several facilities that dislikes vibration in order to reduce daily vibration. In general, vibration isolation devices are intended for high frequency and small amplitude range. However, it is difficult to cut off both vibration region caused by flying object collision and seismic motion with existing technologies. The authors propose insulation of equipment and vibration transmitted through the floor by floating equipment, and have. We have devised and built an air floating device that operates when a trigger input is applied to save the energy of this dynamically acting device. It was estimated by numerical calculation that the aero floating device keeps lifting stably in the condition with the air pressure in the auxiliary air chamber about 75 to 80 kPa. The performance specifications of the proposed device were verified from shaking table test. As a result, the effect of reducing the maximum acceleration by about 1/5 against the seismic motion of El Centro NS, Taft NS, Tohoku NS, and Hachinohe EW was confirmed by floating the mass on the frame assuming the equipment. From the obtained power spectrum diagram (PSD) of the response acceleration, it was confirmed that all frequency components up to 25 Hz is reduced by using proposed aero floating base isolation device.

Effects of Damper Force Ranges and Ground Motion Pulse Periods on the Performance of Semi-Active Isolation Systems

2003 ◽  
Author(s):  
Henri Gavin ◽  
Julie Thurston ◽  
Chicahiro Minowa ◽  
Hideo Fujitani
Keyword(s):  
Ground Motion ◽  
Large Scale ◽  
Base Isolation ◽  
Near Field ◽  
Shaking Table ◽  
Isolation System ◽  
Active Isolation ◽  
Isolation Systems ◽  
Fail Safe ◽  
Strong Ground

A large-scale base-isolated steel structural frame was tested at the shaking table laboratory of the National Research Institute for Earth Sciences and Disaster Prevention. These collaborative experiments featured auto-adaptive media and devices to enhance the performance of passive base isolation systems. The planning of these experiments involved determining appropriate device control methods, the development of a controllable damping device with fail-safe characteristics, and the evaluation of the performance of the controlled isolation system subjected to strong ground motion with pronounced near-field effects. The results of the planning study and their large-scale experimental confirmation provide guidelines for the development and implementation of auto-adaptive damping devices for full scale structures.

Analysis and Experiment on the Effect of Seismic Protection of Buildings by High Damping Rubber Bearings

2004 ◽  
Author(s):  
Jun-Ping Pu ◽  
C. S. Tsai ◽  
Jian-Fa Huang ◽  
Bo-Jen Chen ◽  
Yao-Min Fang
Keyword(s):  
Earthquake Engineering ◽  
Base Isolation ◽  
Steel Structure ◽  
Shaking Table ◽  
Natural Period ◽  
Rubber Bearing ◽  
High Damping Rubber Bearings ◽  
High Damping Rubber Bearing ◽  
High Damping Rubber ◽  
Rubber Bearings

In recent years, many studies on base isolation strategies and devices have been developed and applied in U. S. A., Europe, Japan, and New Zealand. The high damping rubber bearing belongs to one kind of the earthquake-proof ideas of base isolation technologies. The installation of high damping rubber bearings can lengthen the natural period of a building and simultaneously reduce the earthquake-induced energy trying to impart to the building. The objective of this paper is to investigate the base isolation effect of high damping rubber bearings. The uniaxial, biaxial, and triaxial shaking table tests were performed to study the seismic behavior of a 0.4-scale three-story isolated steel structure in the National Center for Research on Earthquake Engineering in Taiwan. The experimental and analytical results show that the nonlinear mechanical characteristics of the high damping rubber bearings can be reasonably simulated.

Seismical Protection Properties of High Damping Rubber Bearing and Lead Rubber Bearing Base Isolation Systems for Multi-Storey RC Buildings

2012 ◽  
Vol 234 ◽  
pp. 90-95 ◽  
Author(s):  
Donato Cancellara ◽  
Fabio de Angelis
Keyword(s):  
Base Isolation ◽  
Response Spectrum ◽  
Limit State ◽  
Three Dimensional ◽  
Elastic Response ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
High Damping Rubber Bearing ◽  
High Damping Rubber ◽  
Isolation Systems

In the present paper two different base isolation systems, designed and verified according to the european seismic code (EC2 and EC8), are compared for evaluating the behaviour of a base isolated building, highly irregular in plan, in presence of a seismic excitation. The devices adopted for realizing the different base isolation systems are the High Damping Rubber Bearing (HDRB) and the Lead Rubber Bearing (LRB) both of them actuated in parallel with a Friction Slider (FS). A dynamic nonlinear analysis for a three-dimensional base isolated structure has been performed. Recorded accelerograms for bi-directional ground motions, compatible with the reference elastic response spectrum for each limit state have been used for a more realistic evaluation of the seismic response of the structure and a more realistic comparative analysis between the base isolated structure with the different considered base isolation systems and the traditional fixed base structure.

scholarly journals Effects of Shape Memory Alloys on Response of Steel Structural Buildings within Near Field Earthquakes Zone

2020 ◽  
Vol 6 (7) ◽  
pp. 1314-1327
Author(s):  
Mahmoud Ahmadinejad ◽  
Alireza Jafarisirizi ◽  
Reza Rahgozar
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Base Isolation ◽  
Near Field ◽  
Seismic Zone ◽  
Isolation System ◽  
Residual Displacements ◽  
Rubber Bearing ◽  
Laminated Rubber Bearing ◽  
Isolation Systems

Base isolation is one of the effective ways for controlling civil engineering structures in seismic zone which can reduce seismic demand. Also is an efficient passive control mechanism that protects its superstructure during an earthquake. However, residual displacement of base-isolation systems, resulting from strong ground motions, remain as the main obstacle in such system’s serviceability after the earthquake. Shape Memory Alloys (SMA) is amongst the newly introduced smart materials that can undergo large nonlinear deformations with considerable dissipation of energy without having any permanent displacement afterward. This property of SMA may be utilized for designing of base isolation system to increase the structure’s serviceability. Here, a proposed semi-active isolation system combines laminated rubber bearing system with shape memory alloy, to take advantage of SMAs high elastic strain range, in order to reduce residual displacements of the laminated rubber bearing. Merits of the system are demonstrated by comparing it to common laminated rubber bearing isolation systems. It is found that the optimal application of SMAs in base-isolation systems can significantly reduce bearings’ residual displacements. In this study, OpenSees program for a three dimensional six-storey steel frame building has been used by locating the isolators under the columns for investigating the feasibility of smart base isolation systems, i.e., the combination of traditional Laminated Rubber Bearing (LRB) with the SMA, in reducing the structure’s isolated-base response to near field earthquake records are examined. Also, a new configuration of SMAs in conjunction with LRB is considered which make the system easier to operate and maintain.

Comparative Studies of Base Isolation Systems Featured with Lead Rubber Bearings and Friction Pendulum Bearings

2016 ◽  
Vol 846 ◽  
pp. 114-119
Author(s):  
Arati Pokhrel ◽  
Jian Chun Li ◽  
Yan Cheng Li ◽  
Nicos Maksis ◽  
Yang Yu
Keyword(s):  
Seismic Isolation ◽  
Base Isolation ◽  
Time History ◽  
Elastic Base ◽  
Base Shear ◽  
Isolation Technique ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
Isolation Systems ◽  
Friction Pendulum

Due to the fact that safety is the major concern for civil structures in a seismic active zone, it has always been a challenge for structural engineers to protect structures from earthquake. During past several decades base isolation technique has become more and more popular in the field of seismic protection which can be adopted for new structures as well as the retrofit of existing structures. The objective of this study is to evaluate the behaviours of the building with different seismic isolation systems in terms of roof acceleration, elastic base shear and inter-storey drift under four benchmark earthquakes, namely, El Centro, Northridge, Hachinohe and Kobe earthquakes. Firstly, the design of base isolation systems, i.e. lead rubber bearing (LRB) and friction pendulum bearing (FPB) for five storey RC building was introduced in detail. The non-linear time history analysis was performed in order to determine the structural responses whereas Bouc-Wen Model of hysteresis was adopted for modelling the bilinear behaviour of the bearings. Both isolation systems increase the fundamental period of structures and reduces the spectral acceleration, and hence reduces the lateral force cause by earthquake in the structures, resulting in significant improvement in building performance; however the Lead Rubber Bearing provided the best reduction in elastic base shear and inter-storey drift (at first floor) for most of the benchmark earthquakes. For the adopted bearing characteristics, FPB provided the low isolator displacement.

Methods of Evaluating Vibration Induced Stress of Small-Bore Piping

2006 ◽  
Author(s):  
Michiyasu Noda ◽  
Michiaki Suzuki ◽  
Akira Maekawa ◽  
Toru Sasaki ◽  
Takeshi Suyama ◽  
...  
Keyword(s):  
Analytical Model ◽  
Fatigue Failure ◽  
Nuclear Power ◽  
Power Plants ◽  
Evaluation Method ◽  
Shaking Table ◽  
Mass Model ◽  
Induced Stress ◽  
Single Mass ◽  
Induced Stresses

The vibration induced fatigue failure of small-bore piping is one of the common causes of failure trouble at nuclear power plants. This failure used to be prevented by calculating and screening vibration induced stresses using the accelerations measured by portable vibrometers, which are easy to handle in the working areas. Though the conventional evaluation method for calculating the vibration induced stress of small-bore piping often adopts the single-mass model, the stresses calculated by the model may be different from the actual ones because of being too simplified. So the purpose of this study is to develop the calculation methods of vibration induced stress for the screening preventing from fatigue failure troubles of small-bore piping using portable vibrometers. Firstly, for comparatively simple small-bore piping using the mock-up model simulating actual simple small-bore piping, shaking table experiments are conducted using sine wave and the field response wave measured on-site. By comparing the vibration induced stresses measured by the strain gauges and calculated using the accelerations, at first the validity of a single-mass model was conducted, and then the evaluation of a two-mass model developed as an improvement calculation model was conducted. As results of comparison, the single-mass model was found to be useful only for screening although the calculated stresses had the deviations and the tendency of an underestimate, and the two-mass model was found to be utilized as better screening because the calculated stresses had better agreement with the measured ones. Next, for small-bore piping with typical pattern configurations consisted of several masses and supports, the model considering the supports and the center of gravity being out of pipe centerline was developed and proposed. Finally, for the more complex small-bore piping with general piping configurations consisted of many bends, branches or joints, the method based on the finite element method analysis and the values measured by a portable vibrometer was developed. In this method, the analytical model was optimized, and the stresses were obtained considering vibration modes as dynamically. Judging from the results checked by numerical analysis, this method was found to be accuracy enough to use for screening, because the analytical model was optimized smoothly and the estimated stresses became to be from 1.1 to 1.4 times to the original true ones that corresponds to the actual ones measured in site.

Shaking Table Test on Seismic Response Properties of “Shicras,” Stones Wrapped in Vegetable Fiber Bags

2013 ◽  
Vol 8 (3) ◽  
pp. 526-533 ◽  
Author(s):  
Hiroshi Fukuyama ◽  
◽  
Masami Fujisawa ◽  
Akio Abe ◽  
Toshikazu Kabeyasawa ◽  
...  
Keyword(s):  
Pacific Coast ◽  
Shaking Table Test ◽  
Base Isolation ◽  
Shaking Table ◽  
Earthquake Response ◽  
Response Properties ◽  
Isolation Systems ◽  
Earthquake Vibration ◽  
Isolation Performance ◽  
Vegetable Fiber

Unique foundations consisting of stones wrapped in vegetable fiber bags called shicra (“woven”) have been found in many Pacific coast ruins constructed about 5,000 years ago as shrines in Peru. A shaking table test was conducted to investigate earthquake response properties of these shicra foundations. Results showed that in base isolation performance, shicra foundations “rolled” during earthquake vibration the same as in the case of roller base isolation systems.

scholarly journals THE INVESTIGATION BASE ISOLATOR IN CONTROLLING THE RESPONSE OF THE STRUCTURES DURING EARTHQUAKES

2018 ◽  
Vol 1 (18) ◽  
Author(s):  
Barghlame Hadi ◽  
Gavgani Hojjat Hashempour
Keyword(s):  
Base Isolation ◽  
Comparative Investigation ◽  
Pendulum System ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
Fixed Base ◽  
High Damping Rubber ◽  
Isolation Systems ◽  
Friction Pendulum ◽  
Base Isolators

Base isolation systems are among the most successful and widely applied methods of mitigatingstructural vibration and damage during seismic events. These systems have been installed in numerousfull-scale structures all around. There are three principal types of base isolators: Lead Rubber Bearing(LRB), High Damping Rubber Bearing (HDRB), and Friction Pendulum System (FPS). It is necessaryto extensively examine the response of different LRB isolators—by combining them with re-centeringand damping properties for isolated steel frame buildings experiencing several NF ground motions. Thepresent research uses comparative-descriptive methodology and application in terms of objectives. Thedata needed for the study were collected using library references and through reviewing related studiesconducted in the past in the same field.Results of the current comparative investigation indicated significant reductions in the storey drift,shear, and acceleration and increment in the storey displacement. According to the findings of thecurrent study, base isolators provide flexibility to massive structures against earthquakes. Thesestructures are situated on rigid soils. Moreover, base isolation was found to be the most effective incontrolling the response of the structures during earthquakes. Finally, shear, storey drift, and storeydisplacement reduce due to the use of base isolators as compared to the fixed-base structure.

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