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.

scholarly journals Pengaruh Penggunaan Base Isolation High Damping Rubber Bearing Pada Struktur Beton Bertulang

2020 ◽  
Vol 6 (2) ◽  
pp. 181-194
Author(s):  
Syahnandito ◽  
Reni Suryanita ◽  
Ridwan
Keyword(s):  
Base Isolation ◽  
Isolation System ◽  
Rubber Bearing ◽  
High Damping Rubber Bearing ◽  
Base Isolator ◽  
Base Isolation System ◽  
High Damping Rubber

Salah satu cara yang dapat dilakukan adalah menggunakan peredam beban gempa dengan sistem isolasi dasar (base isolation system). Penggunaan base isolation system  pada bangunan dapat mengisolasi perambatan getaran akibat gempa dari tanah ke struktur atas bangunan menggunakan komponen berbahan karet. Tujuan penelitian ini adalah untuk menganalisis pengaruh penggunaan sistem isolasi dasar berupa High Damping Rubber Bearing pada periode dan gaya geser dasar  struktur beton bertulang. Objek penelitian adalah bangunan hotel 15 lantai dengan ketinggian 62,9 m. Penelitian diawali dengan pemodelan struktur menggunakan aplikasi ETABS v2016 sehingga didapatkan periode dan gaya geser dasar struktur fixbase. Tahap selanjutnya memberikan gaya pada model struktur dengan isolasi dasar High Dumper Rubber Bearing sehingga didapatkan periode dan gaya geser dasar struktur dengan base isolator. Hasil analisis pada struktur fixbase didapatkan periode sebesar 4,212 detik, dengan gaya geser dasar didapatkan sebesar 1470,725 ton. Sedangkan hasil analisis pada struktur dengan base isolator didapatkan periode sebesar 5,500 detik, dengan gaya geser dasar didapatkan sebesar 1286,071 ton. Maka dapat disimpulkan bahwa pada struktur dengan base isolator terjadi peningkatan periode sebesar 30,58 %, sedangkan gaya geser dasar terjadi penurunan 12,56 %.

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.

A Novel Seismic Base Isolation System Consisting of a Lead Rubber Bearing in Series with a Friction Slider. Part I: Nonlinear Modeling of the System

2012 ◽  
Vol 256-259 ◽  
pp. 2185-2192
Author(s):  
Donato Cancellara ◽  
Fabio de Angelis ◽  
Mario Pasquino
Keyword(s):  
Base Isolation ◽  
Nonlinear Modeling ◽  
Isolation System ◽  
Nonlinear Finite Elements ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
Base Isolator ◽  
Base Isolation System ◽  
In Series ◽  
Seismic Base Isolation

In this paper a new seismic base isolator, called High Damping Hybrid Seismic Isolator (HDHSI), is proposed. It is obtained by the assembly in series of a Lead Rubber Bearing (LRB) and a Friction Slider (FS) with a high friction coefficient. The HDHSI device is in contrast with the Resilient-Friction Base Isolator (R-FBI) with the aim of optimizing the Electricité De France (EDF) system. The mathematical model of a structure base isolated by a HDHSI system is analyzed with a two Degree of Freedom System (2-DOF) in which the superstructure is assimilated to a rigid body. Nonlinear finite elements are adopted for modeling the HDHSI device. A dynamic nonlinear analysis is performed and the hysteretic cycles are derived and evaluated for the single components and for the innovative HDHSI device.

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.

Optimization of Yield Shear Coefficient for Parallel Base Isolation System

2012 ◽  
Vol 166-169 ◽  
pp. 363-366
Author(s):  
Qiang Rong ◽  
Yan Sheng
Keyword(s):  
Objective Function ◽  
Seismic Waves ◽  
Base Isolation ◽  
Energy Scale ◽  
Scale Factor ◽  
Base Shear ◽  
Optimal Range ◽  
Isolation System ◽  
Shear Coefficient ◽  
Base Isolation System

The optimization of yield shear coefficient for parallel base isolation system is investigated systematically. The maximum dissipative energy scale factor is used as the objective function, the maximum sliding displacement of a base-isolated layer, the residual displacement and the maximum base shear coefficient are considered the constraining factors. The optimal range of the yield shear coefficient is proposed by inputting the seismic waves of the different sites.

scholarly journals Influence of Elastomeric Bearings in Tension on the Seismic Performance of Base-Isolated r.c. Buildings

2020 ◽  
Vol 11 (1) ◽  
pp. 82
Author(s):  
Fabio Mazza ◽  
Mirko Mazza
Keyword(s):  
Base Isolation ◽  
Nonlinear Models ◽  
Vertical Component ◽  
Computer Code ◽  
Nonlinear Phenomena ◽  
Isolation System ◽  
Elastomeric Bearings ◽  
Near Fault ◽  
Base Isolation System ◽  
Near Fault Earthquakes

Elastomeric bearings are commonly used in base-isolation systems to protect the structures from earthquake damages. Their design is usually developed by using nonlinear models where only the effects of shear and compressive loads are considered, but uncertainties still remain about consequences of the tensile loads produced by severe earthquakes like the near-fault ones. The present work aims to highlight the relapses of tension on the response of bearings and superstructure. To this end, three-, seven- and ten-storey r.c. framed buildings are designed in line with the current Italian seismic code, with a base-isolation system constituted of High-Damping-Rubber Bearings (HDRBs) designed for three values of the ratio between the vertical and horizontal stiffnesses. Experimental and analytical results available in literature are used to propose a unified nonlinear model of the HDRBs, including cavitation and post-cavitation of the elastomer. Nonlinear incremental dynamic analyses of the test structures are carried out using a homemade computer code, where other models of HDRBs considering only some nonlinear phenomena are implemented. Near-fault earthquakes with comparable horizontal and vertical components, prevailing horizontal component and prevailing vertical component are considered as seismic input. Numerical results highlight that a precautionary estimation of response parameters of the HDRBs is attained referring to the proposed model, while its effects on the nonlinear response of the superstructure are less conservative.

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