The Contrast of Reduction of Seismic Response in Seismic Specification between China and Japan Caused by Equivalent Damping Ratio

2013 ◽  
Vol 740 ◽  
pp. 721-727
Author(s):  
Wen Jing Nie ◽  
Yu Bai ◽  
Hao Wei Kuang
Keyword(s):  
Seismic Response ◽  
Damping Ratio ◽  
Structural Damping ◽  
Calculation Methods ◽  
Equivalent Damping ◽  
China And Japan

The increase in the structural damping ratio can make the degree of seismic response lower, while the damping ratio causes the seismic response differently in the different national specification. The paper first introduces the principle of equivalent damping ratio of the seismic response calculation methods in seismic specification of China and Japan, then analyzes and compares reduction of seismic response caused by the equivalent damping ratio in seismic specification of China and Japan by calculating data.

scholarly journals Influence of Vertical Equivalent Damping Ratio on Seismic Isolation Effectiveness of Nuclear Reactor Building

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4602
Author(s):  
Xiuyun Zhu ◽  
Jianbo Li ◽  
Gao Lin ◽  
Rong Pan
Keyword(s):  
Seismic Response ◽  
Seismic Isolation ◽  
Nuclear Reactor ◽  
Damping Ratio ◽  
Response Spectra ◽  
Horizontal Displacement ◽  
Vertical Displacement ◽  
Vertical Acceleration ◽  
Equivalent Damping ◽  
Reactor Building

This paper aimed at evaluating the influence of different vertical equivalent damping ratios of a 3-dimensional combined isolation bearing (3D-CIB) as regards seismic response and isolation effectiveness. A comparative study of the seismic response in terms of acceleration floor response spectra (FRS), peak acceleration, displacement response of the nuclear reactor building, and dynamic response of the 3D-CIB was carried out. The results showed that: (1) the horizontal FRS is slightly influenced by the vertical equivalent damping ratio of 3D-CIB, whereas the increase of the vertical equivalent damping ratio has a significant effect on reducing the vertical FRS; (2) the peak vertical acceleration increased with the decrease in the vertical equivalent damping ratios of 3D-CIB and the difference of peak accelerations calculated by the damping ratio of 20 and 25% is within 10%; (3) the increase of the vertical equivalent damping ratio is capable of reducing the horizontal displacement and the rocking effect of the superstructure, and effectively controlling the vertical displacement amplitude; and (4) the vertical equivalent damping ratio of 3D-CIB has a slight effect on its axial force. Consequently, it is demonstrated that the increase of the vertical equivalent damping ratio is advantageous for isolation effectiveness. From the view of displacement control, it is suggested that the 3D-CIB with the vertical an equivalent damping ratio of 15~20% is appropriate and acceptable.

Beneficial performance of a quasi-zero stiffness vibration isolator with generalized geometric nonlinear damping

2020 ◽  
pp. 095745652097238
Author(s):  
Chun Cheng ◽  
Ran Ma ◽  
Yan Hu
Keyword(s):  
Damping Ratio ◽  
Nonlinear Damping ◽  
Vibration Isolator ◽  
Equivalent Damping ◽  
Frequency Responses ◽  
Geometric Nonlinear ◽  
Resonant Region ◽  
Force Transmissibility ◽  
Isolation Performance ◽  
Force And Displacement Transmissibility

Generalized geometric nonlinear damping based on the viscous damper with a non-negative velocity exponent is proposed to improve the isolation performance of a quasi-zero stiffness (QZS) vibration isolator in this paper. Firstly, the generalized geometric nonlinear damping characteristic is derived. Then, the amplitude-frequency responses of the QZS vibration isolator under force and base excitations are obtained, respectively, using the averaging method. Parametric analysis of the force and displacement transmissibility is conducted subsequently. At last, two phenomena are explained from the viewpoint of the equivalent damping ratio. The results show that decreasing the velocity exponent of the horizontal damper is beneficial to reduce the force transmissibility in the resonant region. For the case of base excitation, it is beneficial to select a smaller velocity exponent only when the nonlinear damping ratio is relatively large.

scholarly journals Estimation of Additional Equivalent Damping Ratio of the Damped Structure Based on Energy Dissipation

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Xiuyan Hu ◽  
Qingjun Chen ◽  
Dagen Weng ◽  
Ruifu Zhang ◽  
Xiaosong Ren
Keyword(s):  
Energy Dissipation ◽  
Damping Ratio ◽  
Theoretical Concept ◽  
Estimation Methods ◽  
External Excitation ◽  
Single Degree Of Freedom ◽  
Equivalent Damping ◽  
Seismic Motion ◽  
Practical Engineering ◽  
Energy Dissipation Capacity

In the design of damped structures, the additional equivalent damping ratio (EDR) is an important factor in the evaluation of the energy dissipation effect. However, previous additional EDR estimation methods are complicated and not easy to be applied in practical engineering. Therefore, in this study, a method based on energy dissipation is developed to simplify the estimation of the additional EDR. First, an energy governing equation is established to calculate the structural energy dissipation. By means of dynamic analysis, the ratio of the energy consumed by dampers to that consumed by structural inherent damping is obtained under external excitation. Because the energy dissipation capacity of the installed dampers is reflected by the additional EDR, the abovementioned ratio can be used to estimate the additional EDR of the damped structure. Energy dissipation varies with time, which indicates that the ratio is related to the duration of ground motion. Hence, the energy dissipation during the most intensive period in the entire seismic motion duration is used to calculate the additional EDR. Accordingly, the procedure of the proposed method is presented. The feasibility of this method is verified by using a single-degree-of-freedom system. Then, a benchmark structure with dampers is adopted to illustrate the usefulness of this method in practical engineering applications. In conclusion, the proposed method is not only explicit in the theoretical concept and convenient in application but also reflects the time-varying characteristic of additional EDR, which possesses the value in practical engineering.

Effect of guy cable constraint on structural damping of open lattice antenna towers

1980 ◽  
Vol 7 (4) ◽  
pp. 614-620
Author(s):  
J. S. Kennedy ◽  
D. J. Wilson ◽  
P. F. Adams ◽  
M. Perlynn
Keyword(s):  
Natural Frequencies ◽  
Damping Ratio ◽  
Field Tests ◽  
Full Scale ◽  
Structural Damping ◽  
Scale Field ◽  
Modes Of Vibration

This paper presents the results of full-scale field tests on two steel guyed latticed towers. The towers were approximately 83 m in height, were guyed at three levels, and were of bolted angle construction. The observed results consist of the natural frequencies of the first two modes of vibration as well as the damping ratio for the first mode. The observed results are compared with analytical predictions and observations made concerning the contributions of structural and cable action to the damping ratio.

The Influence of Support Hardware and Piping System Seismic Response on Snubber Support Damping

1997 ◽  
Vol 119 (4) ◽  
pp. 451-456 ◽  
Author(s):  
C. Lay ◽  
O. A. Abu-Yasein ◽  
M. A. Pickett ◽  
J. Madia ◽  
S. K. Sinha
Keyword(s):  
Seismic Response ◽  
Fundamental Frequency ◽  
Damping Ratio ◽  
Damping Coefficient ◽  
Piping System ◽  
Nodal Displacement ◽  
Damping Coefficients ◽  
Fundamental Frequencies ◽  
Piping Systems

The damping coefficients and ratios of piping system snubber supports were found to vary logarithmically with pipe support nodal displacement. For piping systems with fundamental frequencies in the range of 0.6 to 6.6 Hz, the support damping ratio for snubber supports was found to increase with increasing fundamental frequency. For 3-kip snubbers, damping coefficient and damping ratio decreased logarithmically with nodal displacement, indicating that the 3-kip snubbers studied behaved essentially as coulomb dampers; while for the 10-kip snubbers studied, damping coefficient and damping ratio increased logarithmically with nodal displacement.

Preparation and Vibration Damping Characteristics of Wide Frequency Domain PVMQ/IIR Foam Materials

2012 ◽  
Vol 538-541 ◽  
pp. 2298-2303
Author(s):  
Shi Kai Luo ◽  
Guo Fang Ding ◽  
Jing Li Li ◽  
Yan Song Sha ◽  
Qing Min Cheng ◽  
...  
Keyword(s):  
Frequency Domain ◽  
Wide Temperature Range ◽  
Damping Ratio ◽  
Vibration Damping ◽  
Simple Equation ◽  
Structural Damping ◽  
Damping Characteristics ◽  
Damping Materials ◽  
Foaming Technology ◽  
Isoprene Rubber

In this paper, we prepared foaming silicon rubber (PVMQ) /isobutylene-isoprene rubber (IIR) composites with chemical foaming technology. The DMA tests results showed that these foaming materials have effective damping characteristics in a wide temperature range. With the special vibrator, we found that the PVMQ/IIR foams that we prepared were the damping materials which has wide frequency domain, because they can keep high damping ratio in a wide frequency domain. When the preloading was between 1.0 mm and 1.7 mm, the structural damping did not change obviously. According to tests, we found that the damping ratio of these foams was fit to the simple equation .

Optimal Design of Vibration Absorber Systems Supported by Elastic Base

1991 ◽  
Author(s):  
Hashem Ashrafiuon
Keyword(s):  
Dynamic Models ◽  
Damping Ratio ◽  
Equations Of Motion ◽  
Elastic Base ◽  
Design Parameters ◽  
Primary System ◽  
Vibration Absorbers ◽  
Equivalent Damping ◽  
System Equations ◽  
Different Levels

Abstract This paper presents the effect of foundation flexibility on the optimum design of vibration absorbers. Flexibility of the base is incorporated into the absorber system equations of motion through an equivalent damping ratio and stiffness value in the direction of motion at the connection point. The optimum values of the uncoupled natural frequency and damping ratio of the absorber are determined over a range of excitation frequencies and the primary system damping ratio. The design parameters are computed and compared for the rigid, static, and dynamic models of the base as well as different levels of base flexibility.

Analysis of Beam-Like Structures With Displacement-Dependent Friction Forces: Part I — Single-Degree-of-Freedom Model

1995 ◽  
Author(s):  
Wayne E. Whiteman ◽  
Aldo A. Ferri
Keyword(s):  
Dry Friction ◽  
Damping Ratio ◽  
Strong Dependence ◽  
Time Integration ◽  
Single Mode ◽  
Stick Slip ◽  
Friction Forces ◽  
Equivalent Damping ◽  
Damping Characteristics ◽  
Parameter Values

Abstract The dynamic behavior of a beam-like structure undergoing transverse vibration and subjected to a displacement-dependent dry friction force is examined. In Part I, the beam is modeled by a single mode while Part II considers multi-mode representations. The displacement dependence in each case is caused by a ramp configuration that allows the normal force across the sliding interface to increase linearly with slip displacement. The system is studied first by using first-order harmonic balance and then by using a time integration method. The stick-slip behavior of the system is also studied. Even though the only source of damping is dry friction, the system is seen to exhibit “viscous-like” damping characteristics. A strong dependence of the equivalent natural frequency and damping ratio on the displacement amplitude is an interesting result. It is shown that for a given set of parameter values, an optimal ramp angle exists that maximizes the equivalent damping ratio. The appearance of two dynamic response solutions at certain system and forcing parameter values is also seen. Results suggest that the overall characteristics of mechanical systems may be improved by properly configuring frictional interfaces to allow normal forces to vary with displacement.

scholarly journals Displacement-Dependent Damping Inerter System for Seismic Response Control

2019 ◽  
Vol 10 (1) ◽  
pp. 257 ◽  
Author(s):  
Zhipeng Zhao ◽  
Ruifu Zhang ◽  
Yiyao Jiang ◽  
Dario De Domenico ◽  
Chao Pan
Keyword(s):  
Energy Dissipation ◽  
Seismic Response ◽  
Early Stage ◽  
Damping Ratio ◽  
Poor Performance ◽  
Linearization Method ◽  
Structural Deformation ◽  
Stochastic Dynamic ◽  
Control Force ◽  
The Time Domain

Various inerter systems utilizing velocity-dependent damping for vibration control have been developed. However, a velocity-dependent damping element may exhibit relatively poor performance compared to a displacement-dependent damping element (DDE) of equivalent damping ratio, when the structural deformation is small in the early stage of the seismic response. To address this issue, the advantage of DDE in generating a larger control force in the early stage of excitation is promoted here and enhanced by a supplemental inerter-spring-system, thus realizing a proposed novel displacement-dependent damping inerter system (DDIS). First, the influence of various DDIS-parameters is carried out by resorting to the stochastic linearization method to handle non-linear terms. Then, seismic responses of the DDIS-controlled system are evaluated in the time domain taking the non-linearity into account, thus validating the accuracy of the stochastic dynamic analysis. Several design cases are considered, all of which demonstrated damping enhancement and timely control achieved by the DDIS. The results show that the energy dissipation as well as reduction of structural displacement and acceleration accomplished by the proposed system are significant. DDIS suppresses structural responses in a timely manner, as soon as the peak excitation occurs. In addition, it is demonstrated that interactions among the inerter, spring, and DDE, which constitute the damping-enhancement mechanism, lead to a higher energy-dissipation efficiency compared to the DDE alone.

Theoretical and experimental studies of a novel nested oscillator with a high-damping characteristic

2020 ◽  
pp. 107754632094378
Author(s):  
Haiping Liu ◽  
Kaili Xiao ◽  
PengPeng Zhao ◽  
Dongmei Zhu
Keyword(s):  
Resonant Frequency ◽  
Vibration Suppression ◽  
Damping Ratio ◽  
Experimental Studies ◽  
Harmonic Balance Method ◽  
Design Parameters ◽  
Base Excitation ◽  
Oscillation System ◽  
Equivalent Damping ◽  
Vibration Transmissibility

Stiffness and damping of a structure usually show the opposite change so that the resonant frequency and the static load bearing capacity of a mechanical system often exhibit contradiction. To solve this dilemma, a novel high-damping oscillator which is constructed by a nested diamond structure with the purpose of enhancing the damping property is proposed in this study without reducing the overall systematic stiffness. The mathematical model and geometrical relationships are established at first. And then, the steady-state solutions under base excitation are derived by using the harmonic balance method and further verified by numerical simulation. In addition, the effects of some design parameters on the equivalent damping ratio for the high-damping oscillator are studied to reveal the nonlinear characteristic. Besides, the natural frequency of the nonlinear oscillator is also presented and investigated. By using the displacement transmissibility and comparing with the traditional linear isolator with the same overall stiffness, the vibration suppression performance of the high-damping oscillator is addressed. The obtained calculating results demonstrate that the vibration control performance of the high-damping oscillator outperforms the linear counterpart around resonant frequency. Moreover, the influences of systematic parameters of the high-damping oscillator for the base excitation case on the vibration transmissibility are also discussed, respectively. Finally, an experimental campaign is conducted on an in-house-built test rig to corroborate the accuracy of the analytical solutions of the high-damping oscillation system. The results discussed in this study provide a useful guideline, which can help to design this class of high-damping oscillation system.

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