scholarly journals Analysis of a Frame-Shear Wall Concrete Structure by Using Base Isolation and Evaluation of Structure-Soil Interaction

2017 ◽  
Vol 7 (6) ◽  
pp. 2282-2287
Author(s):  
H. I. Polat
Keyword(s):  
Cross Sections ◽  
Base Isolation ◽  
Shear Wall ◽  
Structure Design ◽  
Mode Shapes ◽  
Earthquake Response ◽  
Response Analysis ◽  
Seismic Load ◽  
Isolation System ◽  
Base Isolation System

A base isolation system is a type of earthquake-resistant structure design approach based on the principle of reducing a structure’s earthquake response rather than increasing the structure’s earthquake resistance capacity. Seismic base isolated structures have the ability to make large displacements relative to the level of insulation elements. This means that a large structure performs very small displacements between floors during an earthquake and exhibits a rigid body behavior. At this point, the earthquake forces acting on the structure decrease along with the floors. In this article a school building composed of frame-shear wall is resolved primarily with the traditional fixed base structure system, mode shapes are found and periods are obtained. For earthquake response analysis, earthquake loads are distributed to the floors using the equivalent seismic load method and structural elements experiencing capacity problems are found. Then, using the earthquake record, larger failure of cross sections and capacity problems are obtained compared to the first method. In the second stage, the same structure is dissolved again by placing the lead core rubber base isolators between the base and the vertical structural members. The periods of structures under earthquake load have increased significantly by utilizing base isolation, as a result of that spectral accelerations decreased. Thus, large decreases in the shear forces acting to the structure are determined and failures of cross sections are removed.

scholarly journals Influence at Mass of the Base Isolation System in Affecting the Higher Modes of Vibration

2021 ◽  
Vol 12 (2) ◽  
pp. 1809-1815
Author(s):  
Cici Jennifer Raj J, Et. al.
Keyword(s):  
Seismic Waves ◽  
Base Isolation ◽  
Mode Shapes ◽  
Isolation System ◽  
Higher Modes ◽  
Remarkable Effect ◽  
Base Isolator ◽  
Key Factor ◽  
Modes Of Vibration ◽  
Base Isolation System

Base Isolation is a technology of mitigating the effects due to earthquakes with the aspect of dissipating the seismic waves away from the superstructure, by isolating the superstructure from the ground.This concept is widely essential to be implemented in structures(buildings) irrespective of many factors. There are several materials which could be implemented as base isolator, however the need in reduction of the number of the isolators is essential dueto various factors which a developing country finds difficult to implement. In this paper, a three-storey unsymmetrical building to be considered for the study is isolated by varying the mass of the foundation beam, (Transfer beam) thereby reducing the number of isolators in the building.Furthermore,the mode shapes and  frequencies of the structure without base isolation and with base isolation considering mass of the base isolation system as a key factor were analysed and compared and hence the variation in the mass of the isolation system has a promising effect in altering the higher modes of vibration. The analysis is prolonged using  another methd using UBC-1997 provisions and compared. In both the methods, the influence of the mass of the isolation system has a remarkable effect in altering the higher modes of vibration.

Study on the Seismic Load Coupling Effects Due to Horizontal and Vertical Excitation for the Newly Developed 3-Dimensional Base Isolation System

2005 ◽  
Author(s):  
Tomohiro Ito ◽  
Katsuhisa Fujita ◽  
Takeshi Ohkubo
Keyword(s):  
Friction Force ◽  
Base Isolation ◽  
Seismic Load ◽  
Seismic Excitations ◽  
Coupling Effects ◽  
Isolation System ◽  
Vertical Excitation ◽  
3 Dimensional ◽  
Base Isolation System ◽  
Isolation Systems

Recently, many huge earthquakes occurred in many places, such as Hyogo-ken Nambu earthquake in 1995, Kocaeli earthquake and Chi-Chi earthquake in 1999 and Niigata Chuetsu earthquake in 2004 etc., and huge earthquakes are also considered to occur in near future. Therefore, many horizontal isolation structures have been proposed and constructed. In addition to the horizontal isolation, 3-dimensional isolation systems are under development as well. For these reasons, the authors also have developed a new 3-dimensional base isolation system and evaluated the effectiveness of the system. This isolation system employs sliding pads and laminated rubber bearings for horizontal isolation as some other isolation systems do. Thus, the vibration response of the upper structure depends on the friction force between sliding pads and the floor. In the actual seismic events, these sliding type isolation systems suffer from both horizontal and vertical seismic excitations simultaneously. For these reasons, the friction force in the horizontal direction has two components; one depends on the self weight and the other depends on the vertical seismic response. The latter will change time-dependently. Therefore, it can be said that the coupling effects between the horizontal and vertical seismic excitations become predominant. In this study, the coupling effects of the horizontal and vertical seismic excitations are investigated analytically as for the rocking motion, response displacement and response acceleration for the various seismic wave inputs. The effects of the phase difference between the horizontal and vertical seismic input and the amplitude of the vertical excitation are clarified and the design guide lines for the sliding type base isolation systems exposed to the horizontal and vertical simultaneous seismic excitations are proposed.

Bracing Systems for Seismic and Wind Performance of Tall Buildings

2013 ◽  
Vol 650 ◽  
pp. 667-672 ◽  
Author(s):  
Dong Keon Kim ◽  
Jong Wan Hu
Keyword(s):  
Base Isolation ◽  
Tall Buildings ◽  
Wind Load ◽  
Tall Building ◽  
Structural Safety ◽  
Seismic Load ◽  
Isolation System ◽  
Seismic Codes ◽  
The World ◽  
Base Isolation System

Occurrence of frequency of earthquakes around the world has been increased including Sendai earthquake in Japan and magnitude of earthquake has also increased. Recently, many tall buildings using local seismic codes can be exposed to the risk of an earthquake and wind. Also, some buildings, which was planned to be built, were foundered as a result of lack of finance. Therefore, for tall buildings, structural safety such as earthquake and wind resistant performance, and financing issue are very important to progress the huge project. So we need to find another optimum alternative other than damping devices and base isolation system. In this study, four types of test specimens are used, which are fifty-story base tall building, tall building that was reinforced with diagonal brace, x-brace, and Chevron brace. And all of these cases, are subjected to the seismic load and wind load, finally analyzed and compared for seismic and wind performances.

Nonlinear Seismic Response Analysis of Parallel Base-Isolated System

2012 ◽  
Vol 256-259 ◽  
pp. 2254-2257
Author(s):  
Q. Rong
Keyword(s):  
Base Isolation ◽  
Time History ◽  
Treatment Method ◽  
Response Analysis ◽  
Hysteretic Model ◽  
Isolation System ◽  
Nonlinear Seismic Response ◽  
History Analysis ◽  
Base Isolation System ◽  
Single Mass

Based on the bilinear hysteretic model, the elastic-plastic time history analysis of single mass point for parallel base isolation system is carried out. The approximate treatment method of the inflexion point is introduced and the formula of each energy consumption for parallel base-isolated structure is given. Through an engineering example, the time history curve of each energy dissipation for parallel base-isolated system is drawn, and the isolation effect is given.

Study on Multifunctional Base Isolation System Using Air-Floating Technique

2020 ◽  
Author(s):  
Osamu Furuya ◽  
Kiyotaka Takito ◽  
Hiroshi Kurabayashi ◽  
Kunio Sampei ◽  
Koji Yamazaki
Keyword(s):  
Performance Evaluation ◽  
Seismic Isolation ◽  
Vibration Isolation ◽  
Shaking Table Test ◽  
Base Isolation ◽  
Shaking Table ◽  
Response Analysis ◽  
Vibration Isolator ◽  
Isolation System ◽  
Base Isolation System

Abstract Vibration isolation devices are generally applied to equipment that dislikes vibration installed in buildings. Since the vibration isolator is intended for small vibration input, the damage has been frequently confirmed with excessive vibration input such as an huge earthquake motion. Therefore, the development of a seismic isolation device with a vibration isolation function is desired for important equipment and expensive manufacturing equipment. However, the vibration region targeted by the vibration isolator and the vibration region of the seismic input are at completely different levels. In this study, the authors propose a seismic isolation system using air floating technique to cope with such different vibration levels. In this paper, basic concept, basic performance, preliminary performance evaluation by nonlinear time response analysis, and performance evaluation by shaking table test.

21109 Excitation Experiment and Response Analysis for Small Base Isolation System using Friction Bearing

2013 ◽  
Vol 2013.19 (0) ◽  
pp. 513-514
Author(s):  
Mikito KEZUKA ◽  
Katsumi KURITA ◽  
Shigeru AOKI ◽  
Yuji NAKANISHI ◽  
Kazutoshi TOMINAGA ◽  
...  
Keyword(s):  
Base Isolation ◽  
Response Analysis ◽  
Isolation System ◽  
Friction Bearing ◽  
Base Isolation System ◽  
Small Base

Feasibility Tests on a Three-Dimensional Base Isolation System Incorporating Hydraulic Mechanism

2002 ◽  
Author(s):  
Akihiro Kashiwazaki ◽  
Takahiro Shimada ◽  
Tatsuya Fujiwaka ◽  
Katsuhiko Umeki
Keyword(s):  
Seismic Isolation ◽  
Base Isolation ◽  
Three Dimensional ◽  
Scale Model ◽  
Response Analysis ◽  
Isolation System ◽  
Actual Structure ◽  
Load Carrying ◽  
Base Isolation System ◽  
The Government

In Japan, a number of three-dimensional base isolation systems have been studied for application to new nuclear plant concepts such as the FBR, but these efforts have not so far yielded practically applicable results. The impeding factor has been the difficulty of obtaining an adequate capacity on the vertical isolator for supporting the mass of an actual structure and for suppressing rocking motion. In this paper, we propose a new three-dimensional base isolation system that should solve the foregoing problem. The system is constituted of a set of hydraulic load-carrying cylinders connected to accumulator units containing a compressed gas, another set of rocking-suppression cylinders connected in series, and a laminated rubber bearing laid under each load-carrying cylinder. The present paper covers a basic examination for applying the proposed system to a commercialized FBR now under development in Japan, together with static and dynamic loading tests performed on a scale model to verify expected system performance. Response analysis reflecting the test results has indicated the proposed system to be well applicable to the envisaged commercialized FBR. The study was undertaken as part of an R&D project sponsored by the government for realizing a three-dimensional seismic isolation system applicable to future FBR’s.

scholarly journals Seismic Response Analysis of Fully Base-Isolated Adjacent Buildings with Segregated Foundations

2018 ◽  
Vol 2018 ◽  
pp. 1-21 ◽  
Author(s):  
Khaled Ghaedi ◽  
Zainah Ibrahim ◽  
Mohammed Jameel ◽  
Ahad Javanmardi ◽  
Hamed Khatibi
Keyword(s):  
Base Isolation ◽  
Separation Distance ◽  
Response Analysis ◽  
Seismic Gap ◽  
Base Shear ◽  
Earthquake Excitation ◽  
Isolation System ◽  
Adjacent Buildings ◽  
Construction Methods ◽  
Base Isolation System

In populous cities, construction of multistorey buildings close to each other due to space limitation and increased land cost is a dire need. Such construction methods arise several problems during earthquake excitation. The aim of this study is to investigate the bidirectional seismic responses of fully base-isolated (FBI) adjacent buildings having different heights and segregated foundations. Therefore, two scenarios, namely, (a) investigation of the responses of FBI adjacent buildings compared to those with fixed base (FFB) and (b) the effects of separation distance on FBI adjacent buildings, were studied. Based on these investigations, the results showed that isolation system significantly enhances the overall responses of the BI buildings. Spectacularly, the base isolation system was further efficient to decrease displacement rather than the acceleration. In addition, increase of the seismic gap changed the acceleration, pounding, base shear, base moment, and storey drift, as well as the force-deformation performance of the isolators. Therefore, it seems a need to focus on the effect of the separation distances for the design of base isolators for FBI adjacent buildings in future works.

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