scholarly journals Dissipation of Hysteretic Energy in Base Isolated Structure

1996 ◽  
Vol 3 (5) ◽  
pp. 353-359 ◽  
Author(s):  
R.S. Jangid ◽  
T.K. Datta
Keyword(s):  
Base Isolation ◽  
Excitation Frequency ◽  
Harmonic Excitation ◽  
Earthquake Ground Motion ◽  
Hysteretic Energy ◽  
Isolation Frequency ◽  
Time Period ◽  
Base Isolator ◽  
Energy Dissipated ◽  
Mass Level

Dissipation of hysteretic energy in the isolator of the base isolated structure under seismic excitation is investigated. The hysteretic force-deformation characteristics of the base isolator is specified by a nonlinear differential equation. The parameters of the equation can be adjusted to obtain various types of hysteretic models of the isolator including the elastoplastic type. The variation of hysteretic energy dissipated in the isolators is obtained for both harmonic and El-Centro 1940 earthquake ground motion for a set of important parameters. They include time period of superstructure, ratio of superstructure mass to base mass, level of yield strength of the isolator, post- to preyielding stiffness ratio, and the ratio of harmonic excitation frequency to base isolation frequency. It is shown that the dissipation of hysteretic energy in the isolator is significantly influenced by the above parameters.

scholarly journals Seismic performance of double skin semi-base-isolated structures

2020 ◽  
Vol 143 ◽  
pp. 01048
Author(s):  
Congqi Fang ◽  
Wenyan Dong ◽  
Mohammad Parsaeimaram
Keyword(s):  
Seismic Performance ◽  
Inner Core ◽  
Base Isolation ◽  
Lateral Force ◽  
Hysteretic Behavior ◽  
Earthquake Ground Motion ◽  
Coupling Beams ◽  
Isolation System ◽  
Time Period ◽  
Double Skin

Base isolation technology is a popular and powerful isolation technology. This technique can greatly reduce the seismic response of the structure, so as to reduce the damage to the structure. Base isolation method decouples the superstructure from the base by installing a flexible layer under each column to reduce dynamic response in the earthquake and elongate the time period of structures due to its inherent flexibility. However, the long time period causes large displacement. In addition, base isolation devices are highly vulnerable due to uplift forces produced by lateral force resisting systems (LFRS). In this study, an adjustable structure with a new configuration, namely double skin semi-base-isolated (SBI) structure is presented to solve the above problems. The LFRS is omitted in the proposed SBI structure and the time period and displacement are reduced compared to the conventional base-isolated structure. The forcedeformation behavior of an isolator is modeled as bi-linear hysteretic behavior which can be effectively used to model all isolation system in practice. This study investigates the seismic performance of 10-story double skin SBI reinforced concrete (RC) structure under far-fault earthquake ground motion by numerical method. Results demonstrate that the SBI system is significantly adjustable with the use of RC coupling beams between the inner core and outer frames. By increasing or reducing the number of connected floors in the SBI system, dynamic behaviors of the SBI system can be changed. The adjusted structure can be created by adding and removing RC coupling beams at every arbitrary floor level.

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 USED TIRE AS BASE ISOLATOR TIRE FOR EARTHQUAKE RESISTANT HOUSES

2011 ◽  
Vol 7 (1) ◽  
pp. 37
Author(s):  
Inggemar Särfors
Keyword(s):  
Base Isolation ◽  
Load Ratio ◽  
Earthquake Resistance ◽  
Horizontal Load ◽  
Hydraulic Jack ◽  
Earthquake Energy ◽  
Base Isolator ◽  
Earthquake Resistant ◽  
Earthquake Load ◽  
Better Than

The investigation of foundation on tires for absorbing the earthquake energy on houses structure is described here. The foundations are cut cone in shape. There are two tests have been conducted to investigate the shaking energy absorption. First, the foundation is placed on the sand filled tire. The second one, the double tires support round foundation. For comparison purpose, the foundation on sand test without tire is also conducted. The laboratory tests are performed using double hydraulic jack to generate the applied loads. The first jack is used to give the vertical load on the top of foundation to simulate the house load. The other jack is used to produce the load in the horizontal direction to replicate the earthquake load. The results of the tests are plotted in the terms of horizontal load and displacement corves. The double tires foundation shows the higher horizontal displacement-load ratio compared to the others. It indicates that the double tire based foundation absorbing the earthquake energy better than the others. It is concluded that the tired based foundation can be installed to support in the earthquake resistant houses. Keywords: foundation, earthquake resistance, base isolation

Nonlinear Dynamics of a Dielectric Elastomer Membrane Under Compressive Loading

2020 ◽  
Author(s):  
Robert L. Lowe ◽  
Christopher G. Cooley
Keyword(s):  
Nonlinear Dynamics ◽  
Dynamic Response ◽  
Frequency Response ◽  
Compressive Loading ◽  
Excitation Frequency ◽  
Harmonic Excitation ◽  
Dielectric Elastomer ◽  
Large Strains ◽  
Membrane Stretch ◽  
Wide Range

Abstract This paper investigates the nonlinear dynamics of square dielectric elastomer membranes under time-dependent, through-thickness compressive loading. The dielectric elastomer is modeled as an isotropic ideal dielectric, with mechanical stiffening at large strains captured using the Gent hyperelastic constitutive model. The equation of motion for the in-plane membrane stretch is derived using Hamilton’s principle. The static response of the membrane is first investigated, with equilibrium stretches calculated numerically for a wide range of compressive pre-loads and applied voltages. Snap-through instabilities are observed, with the critical snap-through voltage decreasing with increasing compressive pre-load. The dynamic response of the membrane is then investigated under forced harmonic excitation. Frequency response plots characterizing the steady-state vibration reveal primary, subharmonic, and superharmonic resonances. Near these resonances, two stable vibration states are possible, corresponding to upper and lower branches in the frequency response. Significant and practically meaningful differences in the dynamic response are observed when the system vibrates at a fixed frequency about the upper and lower branches, a feature not discussed in previous research.

scholarly journals Research on the Resonance Characteristics of Rock under Harmonic Excitation

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Siqi Li ◽  
Shenglei Tian ◽  
Wei Li ◽  
Tie Yan ◽  
Fuqing Bi
Keyword(s):  
Resonance Frequency ◽  
Natural Frequency ◽  
Excitation Frequency ◽  
Harmonic Excitation ◽  
Theoretical Research ◽  
Transform Method ◽  
Factors Affecting ◽  
Least Action ◽  
Principle Of Least Action ◽  
Resonance Frequencies

In order to study the resonance characteristics of rock under harmonic excitation, two vibration models have been presented to estimate the natural frequency of rock encountered during the drilling. The first one is a developed single-DOF model which considers the properties and dimensions of the rock. The second one is a multi-DOF model based on the principle of least action. Subsequently, the modal characteristics, as well as the influence of excitation frequency, the mechanical properties, and dimensions of the rock on its resonance frequency, are analyzed by using FEM. Finally, the ultrasonic test on artificial sandstones and materials of drill tools are carried out indoor, and the FFT transform method is adopted to obtain their resonance frequencies. Based on the analysis undertaken, it can be concluded that the natural frequency of the rock increases with the change of vibration mode. For the same kind of rock, the resonance frequency is inversely proportional to mass, while for the different kinds of rocks, the mechanical parameters, such as density, elastic modulus, and Poisson’s ratio, determine the resonance frequency of the rock together. Besides, the shape of the rock is also one of the main factors affecting its resonance frequency. At last, the theoretical research results are further verified by ultrasonic tests.

scholarly journals Polymeric Bearings as a new base isolation system suitable for mitigating machine-induced vibrations

2018 ◽  
Vol 211 ◽  
pp. 17001 ◽  
Author(s):  
Tomasz Falborski ◽  
Robert Jankowski
Keyword(s):  
Base Isolation ◽  
Excitation Frequency ◽  
Hysteresis Loops ◽  
Shaking Table ◽  
Damping Properties ◽  
Structural Vibrations ◽  
Isolation System ◽  
Equivalent Damping ◽  
Flexible Polymer ◽  
Base Isolation System

The present paper summarizes the preliminary results of the experimental shaking table investigation conducted in order to verify the effectiveness of a new base isolation system consisting of Polymeric Bearings in reducing strong horizontal machine-induced vibrations. Polymeric Bearing considered in the present study is a prototype base isolation system, which was constructed with the use of a specially prepared flexible polymer with improved damping properties. Dynamic oscillatory tests, during which a concrete base slab supported by four Polymeric Bearings was subjected to horizonal sinusoidal excitations characterized by different frequencies and amplitudes, were conducted in order to determine the damping properties of Polymeric Bearings and their effectiveness in mitigating structural vibrations. Equivalent damping ratios for every excitation frequency considered were determined using the experimentally obtained hysteresis loops. Final conclusions are presented and the results discussed.

Noise and Contact in Dynamic AFM Operations

2011 ◽  
Author(s):  
Ishita Chakraborty ◽  
Balakumar Balachandran
Keyword(s):  
White Noise ◽  
Evolution Equations ◽  
Stochastic Dynamics ◽  
Gaussian White Noise ◽  
Excitation Frequency ◽  
Period Doubling ◽  
Harmonic Excitation ◽  
Dynamic Mode ◽  
Grazing Impacts ◽  
Representative System

In this article, the authors study the effects of Gaussian white noise on the dynamics of an atomic force microscope (AFM) cantilever operating in a dynamic mode by using a combination of numerical and analytical efforts. As a representative system, a combination of Si cantilever and HOPG sample is used. The focus of this study is on understanding the stochastic dynamics of a micro-cantilever, when the excitation frequencies are away from the first natural frequency of the system. In the previous efforts of the authors, period-doubling bifurcations close to grazing impacts have been reported for micro-cantilevers when the excitation frequency is in between the first and the second natural frequencies of the system. In the present study, it is observed that the addition of Gaussian white noise along with a harmonic excitation produces a near-grazing contact, when there was previously no contact between the tip and the sample with only the harmonic excitation. Moment evolution equations derived from a Fokker-Planck system are used to obtain numerical results, which support the statement that the addition of noise facilitates contact between the tip and the sample.

Pushover Analysis of Base Isolated RC Frame Buildings With Masonry Infills

2019 ◽  
Vol 10 (2) ◽  
pp. 18-31
Author(s):  
Radhikesh Prasad Nanda ◽  
Subhrasmita Majumder
Keyword(s):  
Base Isolation ◽  
Plastic Hinge ◽  
Pushover Analysis ◽  
Base Shear ◽  
Infilled Frame ◽  
Masonry Infills ◽  
Time Period ◽  
Frame Buildings ◽  
Story Drift ◽  
Rc Frame Buildings

In the present article, the performance of base-isolated infilled frames is studied analytically. The seismic performances of four RC buildings, namely RC bare frame without isolator, RC bare frame with isolator, RC infilled frame without isolator, and RC infilled frame with isolator are analysed. The results show a decrease in base shear value and increase in time period due to base isolated buildings, while these parameters are reversely affected due to infills. The decrease in story drift for the base isolated buildings is in phase while considering infill. Also, it can be inferred that plastic hinge formation is greatly affected by the introduction of masonry infill. Hence, relying on base isolation without considering infills may underestimate the seismic performance.

Use of Mass as a Perturbation Parameter in Vibrations

1967 ◽  
Vol 89 (4) ◽  
pp. 639-644 ◽  
Author(s):  
R. Chicurel ◽  
J. Counts
Keyword(s):  
Perturbation Technique ◽  
Excitation Frequency ◽  
Perturbation Parameter ◽  
Harmonic Excitation ◽  
Power Series Solution ◽  
Continuous Systems ◽  
Linear Vibration ◽  
Denominator Polynomial ◽  
Vibration Problems ◽  
Special Case

Linear vibration problems involving harmonic excitation of discrete and continuous systems are solved by using the classical perturbation technique. The perturbation parameter is proportional to a mass and the square of the excitation frequency. The power series solution for the displacement of some point in the system is converted to the quotient of two polynomials by the use of continued fractions. The eigenvalues (natural frequencies) of the problem are calculated by finding the roots of the denominator polynomial. The situation wherein a quantity which cannot vanish at any frequency can be found is treated as a special case.

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