A Study on the Response Instability of Seismically Isolated Structures Affected by Ground Inclination During Earthquakes Part 1 : Estimation of Ground Inclination During Earthquakes and the Influence of Static Ground Inclination

2011 ◽  
Vol 6 (3) ◽  
pp. 281-298 ◽  
Author(s):  
Mitsuo Miyazaki ◽  
◽  
Yukihiro Nishimura
Keyword(s):  
Seismic Isolation ◽  
Dynamic Performance ◽  
Restoring Force ◽  
Isolation System ◽  
Strong Earthquakes ◽  
Response Characteristics ◽  
Building Safety ◽  
Isolated Structures ◽  
Isolation Systems ◽  
Ground Motion Records

Seismic isolation can provide superior building safety and dynamic performance during strong earthquakes, however, it is known that some near-source ground motions produce excessive response deformations, which may be larger than the allowable capacity of the isolation devices. Isolation systems with longer periods and higher damping are more capable of resisting such deformations, and the author proposed new isolation systems with periods of 10 sec, or even longer. Longer isolation periods, however, mean less resistance and restoring force in the isolation systems, which may cause concerns about unstable response characteristics during strong earthquakes. One such unstable behavior is the possibility of excessive horizontal displacements of the isolation system resulting from ground inclination. Based on numerical analyses using existing vertical ground motion records, this paper estimates the ground inclination during earthquakes and studies the anticipated horizontal deformation of isolated structures that might be induced by such ground inclination.

Study on Characteristics and Effects of Seismic Isolation System of Vertically Utilized Coiled Springs

2007 ◽  
Author(s):  
Tsuyoshi Fukasawa ◽  
Akihiro Kinoshita ◽  
Satoshi Fujita
Keyword(s):  
Analytical Model ◽  
Seismic Isolation ◽  
304 Stainless Steel ◽  
Restoring Force ◽  
Isolation System ◽  
Static Tests ◽  
Coiled Spring ◽  
Isolation Systems ◽  
Seismic Isolation Systems ◽  
Isolation Performance

In recent years many structures employing seismic isolation systems have been constructed in Japan, the practical concern on the cost of seismic isolation systems has heightened. This paper describes the research and development of a new seismic isolation system using vertically utilized elastic and elasto-plastic coiled spring, and discusses analytical model for coiled spring. The basic concept of the earthquake isolation system that was constituted of bearing, restoration and damping elements is to realize cost effective design without any reduction in isolation performance. The restoration and damping elements of the isolation system were constituted by two types of coiled springs. The horizontal static tests were performed to evaluate the restoring characteristic and the mechanical model of elastic and elasto-plastic coiled spring. The restoration element of elastic coiled springs was made of using the two types of materials JIS SUP9 steel and JIS SUS 304 stainless steel. The elasto-plastic coiled springs of damping element also was made of using the two types of JIS SS 400 steel and JIS SWRM 17 steel. The characteristics of these coiled springs such as transverse stiffness and hysteretic damping and the validity of the analytical model were clarified through the static tests. Furthermore the response analyses based on the restoring force characteristics of experimental results were carried out to assess the isolation performance of this system.

scholarly journals Comparing Rubber Bearings and Eradi-Quake System for Seismic Isolation of Bridges

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5247
Author(s):  
Chang Beck Cho ◽  
Young Jin Kim ◽  
Won Jong Chin ◽  
Jin-Young Lee
Keyword(s):  
Seismic Isolation ◽  
New Technology ◽  
Isolation System ◽  
Seismic Safety ◽  
Response Characteristics ◽  
Rubber Bearing ◽  
Seismic Force ◽  
Isolation Systems ◽  
Rubber Bearings ◽  
Seismic Isolation Systems

Seismic isolation systems have been used worldwide in bridge structures to reduce vibration and avoid collapse. The seismic isolator, damper, and Shock Transmission Unit (SUT) are generally adopted in the seismic design of bridges to improve their seismic safety with economic efficiency. There are several seismic isolation systems, such as Natural Rubber Bearing (NRB), Lead Rubber Bearing (LRB), and the Eradi-Quake System (EQS). EQS as a new technology is expected to effectively reduce both seismic force and displacement, but there is still some need to verify whether it might provide an economical and practical strategy for a bridge isolation system. Moreover, it is important to guarantee consistent performance of the isolators by quality control. A comparative evaluation of the basic properties of the available seismic isolators is thus necessary to achieve a balance between cost-effectiveness and the desired performance of the bridge subjected to extreme loading. Accordingly, in this study, the seismic response characteristics of the seismic isolation systems for bridges were investigated by conducting compressive test and compressive-shear test on NRB, LRB, and EQS.

Development of the EDR-Spring Element Using Foamed Polymer Materials and the Design of NSE-Isolated Buildings Using EDR-Spring Elements

2011 ◽  
Vol 6 (6) ◽  
pp. 668-689
Author(s):  
Mitsuo Miyazaki ◽  
◽  
Yukihiro Nishimura
Keyword(s):  
Strain Energy ◽  
Seismic Isolation ◽  
Ground Motions ◽  
Dynamic Performance ◽  
Polymer Materials ◽  
Resonance Problem ◽  
Predominant Period ◽  
Strong Earthquakes ◽  
Spring Element ◽  
Building Safety

Seismic Isolation can provide superior building safety during strong earthquakes, but it is known that some near-source ground motions produce excessive response deformations, and these may be larger than the allowable capacity of the isolation devices. “Seismic Isolation with No Strain Energy” (NSE), a new isolation concept, has been proposed as a solution to the problem. By eliminating the strain energy stored in deformed isolators, the resulting resonance problem can be completely resolved. The goal of the paper is to successfully produce an NSE spring element which has the restoring characteristics of the EDR-spring model for NSE-isolated buildings. The paper tested 15 foamed polymer materials and selected the most suitable one for the EDR-spring element. It has an elimination ratio of stored strain energy of ß≥0.7. The design loop for the spring using the selected material was established, and two model buildings of 5 stories and 15 stories were designed using the EDR-spring and sliders supporting the buildings’ weight. The designed NSE-isolated buildings’ superior dynamic performance against very strong earthquakes, even in cases in which input ground motions have the same predominant period as the isolated structures, was confirmed by dynamic response analyses.

Geotechnical Seismic Isolation System - Experimental Study

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.

Three Dimensional Seismic Isolation System Using Hydraulic Cylinder

2002 ◽  
Author(s):  
Shinichiro Kajii ◽  
Naoki Sawa ◽  
Nobuhiro Kunitake ◽  
K. Umeki
Keyword(s):  
Seismic Isolation ◽  
Three Dimensional ◽  
Vertical Direction ◽  
Hydraulic Cylinder ◽  
Seismic Load ◽  
3D Seismic ◽  
Isolation System ◽  
Response Characteristics ◽  
Seismic Motion ◽  
Hydraulic Cylinders

A three-dimensional (3D) seismic isolation system for FBR building is under development. The proposed vertical isolation system consists form hydraulic cylinders with water-based liquid and accumulators to support large vertical static load and to realize low natural frequency in the vertical direction. For horizontal isolation, laminated rubber isolator or sliding type isolator will be combined. Because the major part of the feasibility of this isolation system depends on the sealing function and durability of the hydraulic cylinder, a series of feasibility tests of the hydraulic cylinder have been conducted to verify the reliability against seismic load and seismic motion. This paper describes the specification of the seismic isolations system, seismic response characteristics and the results of the feasibility tests of the seal. This study was performed as part of a government sponsored R&D project on 3D seismic isolation.

scholarly journals Simplified Method for the Seismic Design of Low-Rise, Shear Wall Base- Isolated Buildings

2014 ◽  
Vol 8 (1) ◽  
pp. 22-33
Author(s):  
Arturo Tena-Colunga
Keyword(s):  
Seismic Design ◽  
Hybrid Method ◽  
Base Isolation ◽  
Shear Wall ◽  
Static Method ◽  
Isolation System ◽  
Strong Earthquakes ◽  
Wall Structures ◽  
Simplified Method ◽  
Isolated Structures

A simplified method for the seismic design of low-rise, base-isolated shear wall structures is proposed in MOC-2012. This simplified method is basically a hybrid method, where the design of the isolation system is a simpler version for the static method available in US guidelines for the design of base-isolated structures and the design of the superstructure essentially is an improved version of the simplified method for the seismic design of conventional low-rise shear wall structures of Mexican seismic codes. The application of this method and its effectiveness to obtain safe designs is illustrated with a practical example. It is anticipated this simple methodology would help promote the use of base isolation in low-rise shear wall structures and reduce their vulnerability when subjected to strong earthquakes.

Seismic Isolation Analysis on Long-Span Platform Bridge Connecting Twin-Tower Structures

2011 ◽  
Vol 255-260 ◽  
pp. 1225-1229
Author(s):  
Huang Sheng Sun ◽  
Li Nuo Cheng ◽  
Shi Hai Chen
Keyword(s):  
Seismic Isolation ◽  
Seismic Responses ◽  
One Pot ◽  
Isolation System ◽  
High Position ◽  
Long Span ◽  
Steel Truss ◽  
Story Drift ◽  
Isolation Systems ◽  
Rubber Bearings

In order to mitigate the seismic response of twin-tower structure linked by a steel truss platform bridge, as well as to reduce temperature force in the steel truss, eight groups of combined isolation system, each consisting of one pot-type bearing and four rubber bearings, were designed to connect the upper platform bridge to the lower supporting reinforced concrete towers. The features and working principles of the high-position isolation system were described. Then the seismic responses, including displacement, story drift and floor acceleration, of the structure with the isolation systems were calculated and compared with those of the structure with hinge joints in lieu of isolation. It is found that both the structural seismic responses and the temperature forces in the large-span mega-truss structure can be reduced by the high-position isolation system.

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.

Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities: Part 3 — Seismic Response of Crossover Piping for Seismic Isolation System

2014 ◽  
Author(s):  
Akihito Otani ◽  
Teruyoshi Otoyo ◽  
Hideo Hirai ◽  
Hirohide Iiizumi ◽  
Hiroshi Shimizu ◽  
...  
Keyword(s):  
Seismic Response ◽  
Nuclear Power ◽  
Seismic Isolation ◽  
Evaluation Method ◽  
Response Spectrum ◽  
Time History ◽  
Response Analysis ◽  
Isolation System ◽  
Isolation Systems ◽  
Seismic Isolation Systems

This paper, which is part of the series entitled “Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities”, shows the linear seismic response of crossover piping installed in a seismically isolated plant. The crossover piping, supported by both isolated and non-isolated buildings, deforms with large relative displacement between the two buildings and the seismic response of the crossover piping is caused by two different seismic excitations from the buildings. A flexible and robust structure is needed for the high-pressure crossover piping. In this study, shaking tests on a 1/10 scale piping model and FEM analyses were performed to investigate the seismic response of the crossover piping which was excited and deformed by two different seismic motions under isolated and non-isolated conditions. Specifically, as linear response analysis of the crossover piping, modal time-history analysis and response spectrum analysis with multiple excitations were carried out and the applicability of the analyses was confirmed. Moreover, the seismic response of actual crossover piping was estimated and the feasibility was evaluated.

Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities: Part 4 — Failure Behavior of Crossover Piping for Seismic Isolation System

2014 ◽  
Author(s):  
Teruyoshi Otoyo ◽  
Akihito Otani ◽  
Shunsuke Fukushima ◽  
Masakazu Jimbo ◽  
Tomofumi Yamamoto ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Seismic Isolation ◽  
Evaluation Method ◽  
Low Cycle Fatigue ◽  
Response Analysis ◽  
Failure Behavior ◽  
Isolation System ◽  
Isolation Systems ◽  
Seismic Isolation Systems ◽  
Failure Location

This paper provides a part of the series titled “Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities”. This part shows the failure behavior of crossover piping installed in a seismic isolated plant. The considered crossover piping is supported on one side by an isolated building and by a non-isolated building on the other side. During an earthquake, the piping structure is deformed due to the large relative displacements between the two buildings and at the same time excited by the different building seismic responses. Therefore, the high-pressure crossover piping structure requires both flexibility and strength. In this study, 1/10 scaled shaking tests and FEM analyses have been performed to investigate the failure behavior of the crossover piping, where both seismic motions and excitations have been taken into account. It was confirmed that the failure occurs at the piping elbow through low cycle fatigue. Moreover, the results of the elastic-plastic response analysis, which simulates an extreme level of excitation corresponding to more than three times the design level, are in good agreement with the test results. The simulation also succeeded in predicting the experimental failure location.

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