scholarly journals Near-surface frequency-dependent nonlinear damping ratio observation of ground motions using SMART1

2021 ◽  
Vol 147 ◽  
pp. 106798
Author(s):  
Chun-Hsiang Kuo ◽  
Jyun-Yan Huang ◽  
Che-Min Lin ◽  
Chun-Te Chen ◽  
Kuo-Liang Wen
Keyword(s):  
Ground Motions ◽  
Damping Ratio ◽  
Nonlinear Damping ◽  
Frequency Dependent ◽  
Near Surface

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.

Spectral damping scaling factors for horizontal components of ground motions from subduction earthquakes using NGA-Subduction data

2021 ◽  
pp. 875529302110279
Author(s):  
Sanaz Rezaeian ◽  
Linda Al Atik ◽  
Nicolas M Kuehn ◽  
Norman Abrahamson ◽  
Yousef Bozorgnia ◽  
...  
Keyword(s):  
Ground Motions ◽  
Damping Ratio ◽  
Spectral Shape ◽  
Parametric Models ◽  
Scaling Factors ◽  
Global Models ◽  
Motion Models ◽  
Subduction Earthquakes ◽  
Crustal Earthquakes ◽  
Subduction Zone Earthquakes

This article develops global models of damping scaling factors (DSFs) for subduction zone earthquakes that are functions of the damping ratio, spectral period, earthquake magnitude, and distance. The Next Generation Attenuation for subduction earthquakes (NGA-Sub) project has developed the largest uniformly processed database of recorded ground motions to date from seven subduction regions: Alaska, Cascadia, Central America and Mexico, South America, Japan, Taiwan, and New Zealand. NGA-Sub used this database to develop new ground motion models (GMMs) at a reference 5% damping ratio. We worked with the NGA-Sub project team to develop an extended database that includes pseudo-spectral accelerations (PSA) for 11 damping ratios between 0.5% and 30%. We use this database to develop parametric models of DSF for both interface and intraslab subduction earthquakes that can be used to adjust any subduction GMM from a reference 5% damping ratio to other damping ratios. The DSF is strongly influenced by the response spectral shape and the duration of motion; therefore, in addition to the damping ratio, the median DSF model uses spectral period, magnitude, and distance as surrogate predictor variables to capture the effects of the spectral shape and the duration of motion. We also develop parametric models for the standard deviation of DSF. The models presented in this article are for the RotD50 horizontal component of PSA and are compared with the models for shallow crustal earthquakes in active tectonic regions. Some noticeable differences arise from the considerably longer duration of interface records for very large magnitude events and the enriched high-frequency content of intraslab records, compared with shallow crustal earthquakes. Regional differences are discussed by comparing the proposed global models with the data from each subduction region along with recommendations on the applicability of the models.

An Energy-Based Approach to the Generalized Optimal Locations of Viscous Dampers in Two-Way Asymmetrical Buildings

2014 ◽  
Vol 30 (2) ◽  
pp. 867-889 ◽  
Author(s):  
Jui-Liang Lin ◽  
Manh-Tien Bui ◽  
Keh-Chyuan Tsai
Keyword(s):  
Strain Energy ◽  
Ground Motions ◽  
Damping Ratio ◽  
Intrinsic Property ◽  
Simple Approach ◽  
Engineering Practice ◽  
Viscous Dampers ◽  
Response Parameter ◽  
Control Target ◽  
Target Performance

This paper proposes a simple approach to the generalized optimal locations of linear viscous dampers in elastic two-way asymmetrical buildings under bi-directional ground excitations. The control target used in this optimization process is to maximize the average dissipation rate of the overall strain energy of the two-way asymmetrical building under the ground excitation of two bi-directional unit impulses. The proposed control target, referred to as the smeared damping ratio, is an intrinsic property of the building system. Two advantages of the proposed approach appeal to engineering practice. First, the proposed approach does not require a complicated optimization algorithm. Second, due to the employment of an intrinsic property rather than a certain response parameter as the target performance index, the optimal damper locations resulting from the proposed approach are generalized, which are independent on the characteristics of input ground motions.

The influence of the frequency-dependent spherical-wave effect on the near-surface attenuation estimation

2019 ◽  
Vol 67 (2) ◽  
pp. 577-587 ◽  
Author(s):  
Yongzhen Ji ◽  
Shangxu Wang ◽  
Sanyi Yuan ◽  
Binpeng Yan
Keyword(s):  
Spherical Wave ◽  
Wave Effect ◽  
Frequency Dependent ◽  
Near Surface ◽  
Attenuation Estimation

Investigations on a mega–sub isolation system under near-fault ground motions

2021 ◽  
pp. 136943322110262
Author(s):  
Xiangxiu Li ◽  
Ping Tan ◽  
Aiwen Liu ◽  
Xiaojun Li
Keyword(s):  
Failure Mechanism ◽  
Ground Motion ◽  
Failure Probability ◽  
Structural Parameters ◽  
Ground Motions ◽  
Damping Ratio ◽  
Correlation Coefficients ◽  
Isolation System ◽  
Isolation Layer ◽  
Near Fault

The failure mechanism of the mega–sub isolation system under near-fault ground motions is studied in this article. 90 suites of near-fault ground motions collected from 23 earthquakes are adopted to investigate the ground motion intensity indices applicable for the mega–sub isolation system. Then, the sensitivities of the stochastic responses to the structural parameters are analyzed to determine the representative random structural parameters. Furthermore, considering the uncertainties of ground motion characteristics and structural parameters, the seismic fragility is analyzed by the response surface method in order to obtain the failure mechanism of this system under near-fault ground motions. Results show that different intensity indices have various correlation coefficients with the peak responses of the mega–sub isolation system. The correlations of acceleration-related intensity indices are the worst, whereas the correlations of displacement-related intensity indices show high linearity. The sensitivities of the structural responses are weaker to the sub-structure story stiffness but more sensitive to the sub-structure story mass and the stiffness and damping ratio of the isolation layer. The failure probability of the sub-structure is higher than that of the mega-structure under near-fault ground motion. While in the collapse state, the failure probability of the isolation layer is greater than that of the sub-structure.

On Treatment of Nonlinear Damping for Occurrence of Damping-Controlled Fluid-Elastic Instability

2006 ◽  
Author(s):  
Tomomichi Nakamura
Keyword(s):  
Vibration Amplitude ◽  
Damping Ratio ◽  
Nonlinear Damping ◽  
Critical Flow ◽  
Elastic Instability ◽  
Structural Damping ◽  
Critical Flow Velocity ◽  
Great Problem ◽  
Increasing Trend ◽  
Negative Damping

An estimated damping ratio is used to evaluate the occurrence of the fluid-elastic instability. However, many structures contain some nonlinearity, especially in their damping ratios. Then, it is a great problem what damping value should be used for the estimation of the critical flow velocity. As the nonlinear damping usually shows an increasing trend with the vibration amplitude of tubes, vibrations of a tube with the negative damping due to the fluid flow are calculated for some parametric cases, where the structural damping component has a linear relation to the tube-amplitude. The results show the tube plays as a kind of limit cycle in a few seconds, and the final amplitude depends on the nonlinear trend of the structural damping. It is suggested that this nonlinear damping trend should be used for the design estimation of the fluid-elastic instability.

scholarly journals A Truncated Low Approach of Intrinsic Linear and Nonlinear Damping in Thin Structures

2006 ◽  
Vol 129 (1) ◽  
pp. 32-38
Author(s):  
Yves Gourinat ◽  
Victorien Belloeil
Keyword(s):  
Experimental Data ◽  
Damping Ratio ◽  
Vibrational Analysis ◽  
Nonlinear Damping ◽  
Thin Structures ◽  
Adaptive Approach ◽  
Equivalent Damping ◽  
Linear And Nonlinear ◽  
Algebraic Representations

An adaptive approach of vibrating thin structures is proposed here. The method consists in applying an equivalent adimensional damping ratio to each potential resonance. This ratio is deduced from experimental data obtained in vacuum facility, in relation with frequencies, for several structural technologies. Consequently, it is possible to calculate the structure in a linear nondissipative context, valid out of resonance bands, and truncated in those bands. Thus, the equivalent damping ratio is directly used to define adimensional resonance truncation bandwith and level. The contribution consists in tested and applied modal methodology and algebraic representations of damping including several dissipations—viscous and internal microfrictions—inducing a nonmonotonous model. The here aim is to provide realistic recommendations for simple vibrational analysis of aerospace thin structures—panels and stiffeners.

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