scholarly journals Comparative analysis of conventional and new seismically isolated structure

2021 ◽  
Vol 64 (3) ◽  
pp. 185-193
Author(s):  
Jelena Ristić ◽  
Miloš Vučinić ◽  
Danilo Ristić ◽  
Milutin Vučinić
Keyword(s):  
Seismic Isolation ◽  
Low Cost ◽  
Seismic Energy ◽  
Seismic Excitation ◽  
Isolation System ◽  
Vibration Period ◽  
International Projects ◽  
Dominant Period ◽  
Efficient Protection ◽  
Seismically Isolated

Extensive analytical and experimental research has been done by the authors directed to mitigation of the effects of earthquakes on structures. The research results mainly represent parts of the realized several related international projects. A selected part of the analytical studies directed to comparison between conventional and seismically isolated frame structures is presented in this paper. The responses of the applied newely developed advanced seismic isolation system HC-RMS-GOSEB to the simulated input excitation of three representative earthquakes of intensity 0.50g, have shown that it is very effective for construction of vibro-isolated and seismically resistant buildings, providing activated multistage seismic response and globally optimized seismic energy balance. Its application achieves an increase in the vibration period of the structure, far enough from the dominant period of seismic excitation. The results of the research confirm that this system is a potential solution for achieving low-cost and highly efficient protection of buildings.

scholarly journals Large-scale experimental investigation of a low-cost PVC ‘sand-wich’ (PVC-s) seismic isolation for developing countries

2020 ◽  
Vol 36 (4) ◽  
pp. 1886-1911 ◽  
Author(s):  
Anastasios Tsiavos ◽  
Anastasios Sextos ◽  
Andreas Stavridis ◽  
Matt Dietz ◽  
Luiza Dihoru ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Developing Countries ◽  
Ground Motion ◽  
Seismic Isolation ◽  
Large Scale ◽  
Low Cost ◽  
Seismic Energy ◽  
Earthquake Ground Motion ◽  
Isolation System ◽  
Seismically Isolated

This study presents a large-scale experimental investigation on the seismic performance of an innovative, low-cost seismic isolation system for developing countries. It is based on the beneficial effect of the encapsulation of sand grains between two PVC surfaces on the initiation of sliding and the dissipation of seismic energy between the surfaces. A three-times scaled-down, idealized, seismically isolated model of a prototype single-story structure located in Nepal is subjected to an ensemble of recorded earthquake ground motion excitations. The experimentally derived response of the seismically isolated structure is compared with the response of the corresponding fixed-base structure. This system is part of a wider hybrid design approach where the structure is designed to resist the seismic forces at the design acceleration level. The seismic isolation system sets an upper bound to the response of the structure for ground motion excitations exceeding the design level.

Full-Scale Dynamic Testing of a Sliding Seismically Isolated Unibody House

2016 ◽  
Vol 32 (4) ◽  
pp. 2245-2270 ◽  
Author(s):  
Ezra Jampole ◽  
Gregory Deierlein ◽  
Eduardo Miranda ◽  
Benjamin Fell ◽  
Scott Swensen ◽  
...  
Keyword(s):  
Seismic Isolation ◽  
Computational Models ◽  
Low Cost ◽  
Ground Motions ◽  
Design Guidelines ◽  
Full Scale ◽  
Shaking Table ◽  
Galvanized Steel ◽  
Isolation System ◽  
Seismically Isolated

Shaking table tests were conducted on a new low cost sliding seismic isolation system aimed at significantly improving the seismic performance of low-rise lightweight residential construction. A two-story, full-scale seismically isolated wood frame house was tested dynamically under multiple ground motions on a shake table. Two different sliding isolation bearings were evaluated, one with flat and another with concave sliding surfaces, both with high-density polyethylene sliders on galvanized steel surfaces with a coefficient of friction of approximately 0.18. Each isolation system was subjected to seven severe recorded earthquake ground motions, which produced peak isolator displacements of up to 41 cm. The maximum induced inertial shear force on the superstructure was on the order of 0.4 g, yet the house remained practically damage-free with story drift ratios less than 0.1%. The study successfully (1) provides a proof-of-concept for design, construction, and behavior of a light-frame house with low-cost high friction sliding seismic isolation, (2) confirms several design assumptions regarding isolation behavior and maximum isolation displacement, and (3) provides data to validate computational models and develop design guidelines for the isolated superstructure.

Shaking Table Tests With Large Test Specimens of Seismically Isolated FBR Plants: Part 1—Response Behavior of Test Specimen Under Design Ground Motions

2009 ◽  
Author(s):  
Seiji Kitamura ◽  
Masaki Morishita ◽  
Shuichi Yabana ◽  
Kazuta Hirata ◽  
Katsuhiko Umeki
Keyword(s):  
Test Specimen ◽  
Seismic Isolation ◽  
Ground Motions ◽  
Shaking Table ◽  
Scale Model ◽  
Seismic Load ◽  
Response Behavior ◽  
Isolation System ◽  
Seismically Isolated ◽  
Behavior Test

The seismic isolation technology is planned to introduce to the next generation’s fast breeder reactor (FBR) plants in order to reduce seismic load subjected to components. To grasp the ultimate behavior of a seismically isolated plant under extremely strong earthquake at a level beyond the design ground motions and to establish ultimate strength design methods of seismic isolators, we made a series of shaking table test with large test specimen of seismically isolated FBR plants. The ultimate behavior test was performed using one of the world largest three-dimensional shaking tables “E-Defense” of National Research Institute for Earth Science and Disaster Prevention of Japan to obtain ultimate behavior data of a technologically-feasible large scale model. Test specimen consists of concrete blocks, reinforced concrete walls and isolation layer with six laminated rubber bearing with lead plug (LBR). The gross mass of upper structure of the test specimen is about 600ton. The diameter of the LRB is 505mm that reduced prototype dimensions to about 1/3. In this study, the following three behaviors were assumed as the ultimate behavior of the seismic isolation system; 1) loss of response reduction function of the isolation system by hardening of rubber, 2) non-linear response behavior by the cracking of the concrete wall and 3) braking of the LRB. When the input acceleration level increased, the test specimen was designed to show the ultimate behavior in the above-mentioned order. The ultimate behavior test of the seismic isolation system was carried out on the condition of two input waves by using two test specimen sets of the same dimensions. In this paper, details of the test specimen including the LRB and loading conditions are described. Response behavior of the test specimen under design ground motions is also reported. The restoring force characteristics of the LRBs were stable. The response acceleration of a horizontal direction measured at the upper structure of the specimen was reduced. Prior to the ultimate behavior tests with strong input waves, the response reduction functions of the test specimen under design ground motions were confirmed.

Current State of Seismic-Isolation Design

2009 ◽  
Vol 4 (3) ◽  
pp. 175-181 ◽  
Author(s):  
Nagahide Kani ◽  
Keyword(s):  
Seismic Isolation ◽  
Structural Safety ◽  
Current Status ◽  
Property Value ◽  
Isolation System ◽  
High Rise ◽  
Current State ◽  
Safety Property ◽  
Seismically Isolated ◽  
Resistance Performance

Japan has the world’s highest number of seismic-isolation structures - a figure that has been gradually increasing since the 1995 South Hyogo earthquake that devastated Kobe and its environs. It is the main reason that two seismically isolated buildings in Kobe have shown good performance during and after earthquakes. As the awareness of the benefits of seismic isolation has grown, it is being accepted more among people, to maintain structural safety and functionality during and after earthquakes. Safety, property value, and functionality must be maintained by the earthquake-resistance performance of buildings. This seismic isolation system is the appropriate earthquake-resistant method in consideration of satisfying these three items, and positive in the design of structures, such as residences, hospitals, and high-rise buildings, then in retrofitting. This paper focuses on the current status of seismically isolated structures and problems in seismic isolation design.

scholarly journals Fragility Assessments of Multi-Story Piping Systems within a Seismically Isolated Low-Rise Building

2018 ◽  
Vol 10 (10) ◽  
pp. 3775 ◽  
Author(s):  
Yonghee Ryu ◽  
Shinyoung Kwag ◽  
Bu‐Seog Ju
Keyword(s):  
Seismic Isolation ◽  
Ground Motions ◽  
Seismic Energy ◽  
Analytical Models ◽  
Piping System ◽  
Building Structure ◽  
Strong Ground Motions ◽  
Piping Systems ◽  
Seismically Isolated ◽  
Strong Ground

A successful, advanced safety design method for building and piping structures is related to its functionality and sustainability in beyond-design-basis events such as extremely strong ground motions. This study develops analytical models of seismically isolated building-piping systems in which multi-story piping systems are installed in non-isolated and base-isolated, low-rise buildings. To achieve the sustainable design of a multi-story piping system subjected to strong ground motions, Triple Friction Pendulum (TFP) elements, specifically TFP bearings, were incorporated into the latter building structure. Then, a seismic fragility analysis was performed in consideration of the uncertainty of the seismic ground motions, and the piping fragilities for the seismically non-isolated and the base-isolated building models were quantified. Here, the failure probability of the piping system in the non-isolated building was greater than that in the seismically isolated building. The seismic isolation design of the building improved the sustainability and functionality of the piping system by significantly reducing the seismic energy of extreme ground motions which was input to the building structure itself.

Improvement of the polyurethane spring isolation device for HV post insulators and its evaluation by fragility curves

2021 ◽  
pp. 875529302098196
Author(s):  
Tansu Gökçe ◽  
Engin Orakdöğen ◽  
Ercan Yüksel
Keyword(s):  
Seismic Isolation ◽  
Base Isolation ◽  
Numerical Models ◽  
Fragility Curves ◽  
Low Cost ◽  
Steel Plates ◽  
Isolation System ◽  
Base Isolation System ◽  
Isolation Device ◽  
Seismic Base Isolation

A novel seismic base isolation system has been developed for high-voltage (HV) porcelain post insulators. The seismic isolation device consists of two steel plates, four polyurethane springs, and a steel rod, which are low-cost components compared to the post insulators. Two alternative designs of the device are experimentally and numerically assessed in this article. A simple and robust numerical model consisting of linear line elements and nonlinear springs was generated, and subsequently validated using the experimental results. Incremental dynamic analyses (IDAs) were then performed to obtain fragility curves. Ten historical earthquake profiles, scaled to intensities between 0.1 and 2.0 g, were then applied to the numerical models. The fragility curves, generated according to the latest version of IEEE-693, demonstrate that the seismic isolation devices are highly effective in diminishing the base moment of the porcelain insulator. It should be noted that relatively large displacements at the top of the pole must be accounted for by ensuring adequate slackness in the flexible conductors.

scholarly journals Analytical and Experimental Overview of Fiber Reinforced Elastomeric Isolator

2021 ◽  
Vol 9 (VII) ◽  
pp. 3906-3911
Author(s):  
Afroz Qureshi
Keyword(s):  
Seismic Isolation ◽  
Seismic Waves ◽  
Base Isolation ◽  
Low Cost ◽  
Fiber Reinforced ◽  
Effective Response ◽  
Isolation System ◽  
Vertical Stiffness ◽  
Base Isolation System ◽  
Fiber Reinforced Elastomeric Isolator

There has been many researches in order to further improve the Base Isolation system by trying various combinations and alternative materials. In that fiber reinforced isometric isolators are emerged as a viable solution, because for the low cost and effective response to seismic waves as compared to the conventional isolators. Studies further shows that it provides high vertical stiffness and low horizontal stiffness, also having effective damping over the conventional one. Developing countries who doesn’t have proper seismic protection solutions have found this convenient as they are comparatively less in cost and doesn’t require complex installation. Studies also shows Un-bonded FREI has lower horizontal stiffness and considerably lower stress demand on rubber material as compared to the B-FREI and hence significantly higher seismic isolation efficiency.

Shaking Table Tests With Large Test Specimens of Seismically Isolated FBR Plants: Part 3—Ultimate Behavior of Upper Structure and Rubber Bearings

2009 ◽  
Author(s):  
Shuichi Yabana ◽  
Kenji Kanazawa ◽  
Seiji Nagata ◽  
Seiji Kitamura ◽  
Takeshi Sano
Keyword(s):  
Seismic Isolation ◽  
Response Spectra ◽  
Shaking Table ◽  
Shaking Table Tests ◽  
Nuclear Facilities ◽  
Restoring Force ◽  
Isolation System ◽  
Seismically Isolated ◽  
Design Earthquake ◽  
Rubber Bearings

This paper describes results of shaking table tests to grasp ultimate behavior of seismic isolation system under extremely strong earthquake motions, including failure of rubber bearings. The results of the shaking table tests are expected to be useful for the design of seismically isolated nuclear facilities, especially fast breeder reactor (FBR) plants. In the test, lead rubber bearings, of which the diameter is 505 mm and about 1/3 scale of a prototype in planning FBR plants, are used; the test specimens are loaded by the largest three-dimensional shaking table in E-defense of National Research Institute for Earth Science and Disaster Prevention (NIED) of Japan. Failure of rubber bearings occurs with amplified tentative design earthquake motions. From the tests, the ultimate responses of the upper structure and rubber bearings are presented. In particular, the change of floor response spectra and restoring force characteristics of rubber bearings according to increase of input motions is discussed. Furthermore, mechanism of the failure of rubber bearings is investigated from the observation of failure surfaces and cut sections, static loading tests, and material tests of rubber bearings. Finally, the function of seismic isolation system after the failure of a part of rubber bearings is confirmed under the tentative design earthquake.

scholarly journals Assessment of Geotechnical Seismic Isolation (GSI) as a Mitigation Technique for Seismic Hazard Events

Geosciences ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 222 ◽  
Author(s):  
Davide Forcellini
Keyword(s):  
Seismic Isolation ◽  
Low Cost ◽  
Soil Layer ◽  
Seismic Energy ◽  
Historical Earthquakes ◽  
Structural Configurations ◽  
Numerical Finite Element ◽  
Isolation Systems ◽  
Seismic Isolation Systems ◽  
Mitigation Technique

Geotechnical seismic isolation (GSI) has emerged as a potential technique to mitigate the effects of earthquakes, with many applications to structural configurations, such as bridges and buildings. It consists of absorbing the seismic energy from the soil to the superstructure by interposing a superficial soil layer in order to reduce the accelerations that filter from the soil to the structure. This mitigation technique is particularly suitable in developing countries since GSIs are low-cost seismic isolation systems that through relatively simple manufacturing processes allow to safe costs and stimulate many applications. The presented study aimed to perform 3D numerical finite element models that overcome the previous contributions by performing several structural configurations. Several historical earthquakes are considered in this paper, and the results may be applied to drive general assessments of the technique in case of future seismic hazards.

Seismic Isolation of the IRIS Nuclear Plant

2009 ◽  
Author(s):  
Massimo Forni ◽  
Alessandro Poggianti ◽  
Fosco Bianchi ◽  
Giuseppe Forasassi ◽  
Rosa Lo Frano ◽  
...  
Keyword(s):  
Seismic Isolation ◽  
Seismic Analysis ◽  
Wide Spectrum ◽  
Seismic Excitation ◽  
Fragility Analysis ◽  
Pressurized Water ◽  
Isolation System ◽  
Order Of Magnitude ◽  
Safety Features ◽  
The Impact

The safety-by-design™ approach adopted for the design of the International Reactor Innovative and Secure (IRIS) resulted in the elimination by design of some of the main accident scenarios classically applicable to Pressurized Water Reactors (PWR) and to the reduction of either consequences or frequency of the remaining classical at-power accident initiators. As a result of such strategy the Core Damage Frequency (CDF) from at-power internal initiating events was reduced to the 10−8/ry order of magnitude, thus elevating CDF from external events (seismic above all) to an even more significant contributor than what currently experienced in the existing PWR fleet. The same safety-by-design™ approach was then exported from the design of the IRIS reactor and of its safety systems to the design of the IRIS Nuclear Steam Supply System (NSSS) building, with the goal of reducing the impact of seismically induced scenarios. The small footprint of the IRIS NSSS building, which includes all Engineered Safety Features (ESF), all the emergency heat sink and all the required support systems makes the idea of seismic isolation of the entire nuclear island a relatively easy and economically competitive solution. The seismically isolated IRIS NSSS building dramatically reduces the seismic excitation perceived by the reactor vessel, the containment structure and all the main IRIS ESF components, thus virtually eliminating the seismic-induced CDF. This solution is also contributing to the standardization of the IRIS plant, with a single design compatible with a variety of sites covering a wide spectrum of seismic conditions. The conceptual IRIS seismic isolation system is herein presented, along with a selection of the preliminary seismic analyses confirming the drastic reduction of the seismic excitation to the IRIS NSSS building. Along with the adoption of the seismic isolation system, a more refined approach to the computation of the fragility analysis of the components is also being developed, in order to reduce the undue conservatism historically affecting seismic analysis. The new fragility analysis methodology will be particularly focused on the analysis of the isolators themselves, which will now be the limiting components in the evaluation of the overall seismic induced CDF.

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