A time‐frequency dependent coherence model for seismic ground motions

2020 ◽  
Author(s):  
X.Z. Cui ◽  
H.P. Hong
Keyword(s):  
Ground Motions ◽  
Frequency Dependent ◽  
Time Frequency

scholarly journals Simulation of non-stationary stochastic ground motions based on recent Italian earthquakes

2021 ◽  
Author(s):  
Fabio Sabetta ◽  
Antonio Pugliese ◽  
Gabriele Fiorentino ◽  
Giovanni Lanzano ◽  
Lucia Luzi
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Strong Motion ◽  
Stochastic Simulations ◽  
Model Parameters ◽  
Motion Model ◽  
Arias Intensity ◽  
Time Frequency ◽  
Ground Motion Model ◽  
Ground Motion Records

AbstractThis work presents an up-to-date model for the simulation of non-stationary ground motions, including several novelties compared to the original study of Sabetta and Pugliese (Bull Seism Soc Am 86:337–352, 1996). The selection of the input motion in the framework of earthquake engineering has become progressively more important with the growing use of nonlinear dynamic analyses. Regardless of the increasing availability of large strong motion databases, ground motion records are not always available for a given earthquake scenario and site condition, requiring the adoption of simulated time series. Among the different techniques for the generation of ground motion records, we focused on the methods based on stochastic simulations, considering the time- frequency decomposition of the seismic ground motion. We updated the non-stationary stochastic model initially developed in Sabetta and Pugliese (Bull Seism Soc Am 86:337–352, 1996) and later modified by Pousse et al. (Bull Seism Soc Am 96:2103–2117, 2006) and Laurendeau et al. (Nonstationary stochastic simulation of strong ground-motion time histories: application to the Japanese database. 15 WCEE Lisbon, 2012). The model is based on the S-transform that implicitly considers both the amplitude and frequency modulation. The four model parameters required for the simulation are: Arias intensity, significant duration, central frequency, and frequency bandwidth. They were obtained from an empirical ground motion model calibrated using the accelerometric records included in the updated Italian strong-motion database ITACA. The simulated accelerograms show a good match with the ground motion model prediction of several amplitude and frequency measures, such as Arias intensity, peak acceleration, peak velocity, Fourier spectra, and response spectra.

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

A Time–Frequency Representation Model for Seismic Ground Motions

2020 ◽  
Author(s):  
Xi Zhong Cui ◽  
Han Ping Hong
Keyword(s):  
Ground Motions ◽  
Seismic Source ◽  
Model Parameters ◽  
Time Frequency ◽  
Motion Models ◽  
Power Spectral ◽  
Frequency Representation ◽  
Site Characteristics ◽  
S Transform ◽  
Proposed Model

ABSTRACT A probabilistic model of the time–frequency power spectral density (TFPSD) is presented. The model is developed, based on the time–frequency representation of records from strike-slip earthquakes, in which the time–frequency representation is obtained by applying the S-transform (ST). The model for the TFPSD implicitly considers the amplitude modulation and frequency modulation for the nonstationary ground motions; this differs from the commonly used evolutionary PSD model. Predicting models for the model parameters, based on seismic source and site characteristics, are developed. The use of the model to simulate ground motions for scenario seismic events is illustrated, in which the simulation is carried out using a recently developed model that is based on the discrete orthonormal ST and ST. The illustrative example highlights the simplicity of using the proposed model and the physical meaning of some of the model parameters. A model validation analysis is carried out by comparing the statistics of the pseudospectral acceleration obtained from the simulated records to those obtained using a few ground-motion models available in the literature and considered actual records. The comparison indicates the adequacy of the proposed model.

A Study on Maximum Responses and Their Variances of Elasto-Plastic Structures Subjected to Synthesized Ground Motions

2014 ◽  
Author(s):  
Akira Sone ◽  
Ichiro Ichihashi ◽  
Arata Masuda
Keyword(s):  
Wavelet Transform ◽  
Coefficient Of Variation ◽  
Response Spectrum ◽  
Ground Motions ◽  
Frequency Characteristics ◽  
Target Response ◽  
Maximum Displacement ◽  
Time Frequency ◽  
Earthquake Ground Motions ◽  
The Given

A number of artificial earthquake ground motions compatible with time-frequency characteristics of recorded actual earthquake ground motions as well as the given target response spectrum are generated using wavelet transform. The coefficient of variation (C.O.V..) of maximum displacement on elasto-plastic SDOF systems excited by these artificial ground motions are numerically evaluated.

Robust Empirical Time–Frequency Relations for Seismic Spectral Amplitudes, Part 2: Model Uncertainty and Optimal Parameterization

2020 ◽  
Author(s):  
Maryam Safarshahi ◽  
Igor B. Morozov
Keyword(s):  
Measurement Errors ◽  
Nonparametric Model ◽  
Model Parameters ◽  
Geometrical Spreading ◽  
Model Quality ◽  
Frequency Dependent ◽  
Time Frequency ◽  
Trade Offs ◽  
Frequency Independent ◽  
Seismic Amplitudes

ABSTRACT In a companion article, Safarshahi and Morozov (2020) argued that construction of distance- and frequency-dependent models for seismic-wave amplitudes should include four general elements: (1) a sufficiently detailed (parametric or nonparametric) model of frequency-independent spreading, capturing all essential features of observations; (2) model parameters with well-defined and nonoverlapping physical meanings; (3) joint inversion for multiple parameters, including the geometrical spreading, Q, κ, and source and receiver couplings; and (4) the use of additional dataset-specific criteria of model quality, while fitting the logarithms of seismic amplitudes. Some of these elements are present in existing models, but, taken together, they are poorly understood and require an integrated approach. Such an approach was illustrated by detailed analysis of an S-wave amplitude dataset from southern Iran. The resulting model is based on a frequency-independent Q, and matches the data closer than conventional models and across the entire epicentral-distance range. Here, we complete the analysis of this model by evaluating the uncertainties and trade-offs of its parameters. Two types of trade-offs are differentiated: one caused by a (possibly) limited model parameterization and the second due to statistical data errors. Data bootstrapping shows that with adequate parameterization, attenuation properties Q, κ, and geometrical spreading parameters are resolved well and show moderate trade-offs due to measurement errors. Using the principal component analysis of these trade-offs, an optimal (trade-off free) parameterization of seismic amplitudes is obtained. By contrast, when assuming theoretical values for certain model parameters and using multistep inversion procedures (as commonly done), parameter trade-offs increase dramatically and become difficult to assess. In particular, the frequency-dependent Q correlates with the distribution of the source and receiver-site factors, and also with biases in the resulting median data residuals. In the new model, these trade-offs are removed using an improved parameterization of geometrical spreading, constant Q, and model quality constraints.

scholarly journals Interactions of monovalent cations with sodium channels in squid axon. II. Modification of pharmacological inactivation gating.

1985 ◽  
Vol 85 (4) ◽  
pp. 603-620 ◽  
Author(s):  
J Z Yeh ◽  
G S Oxford
Keyword(s):  
Dissociation Constants ◽  
Mutual Exclusion ◽  
Na Channels ◽  
Frequency Dependent ◽  
Time Frequency ◽  
Drug Molecules ◽  
Voltage Dependent ◽  
Na Ions ◽  
Time Courses ◽  
A Site

The time-, frequency-, and voltage-dependent blocking actions of several cationic drug molecules on open Na channels were investigated in voltage-clamped, internally perfused squid giant axons. The relative potencies and time courses of block by the agents (pancuronium [PC], octylguanidinium [C8G], QX-314, and 9-aminoacridine [9-AA]) were compared in different intracellular ionic solutions; specifically, the influences of internal Cs, tetramethylammonium (TMA), and Na ions on block were examined. TMA+ was found to inhibit the steady state block of open Na channels by all of the compounds. The time-dependent, inactivation-like decay of Na currents in pronase-treated axons perfused with either PC, 9-AA, or C8G was retarded by internal TMA+. The apparent dissociation constants (at zero voltage) for interaction between PC and 9-AA with their binding sites were increased when TMA+ was substituted for Cs+ in the internal solution. The steepness of the voltage dependence of 9-AA or PC block found with internal Cs+ solutions was greatly reduced by TMA+, resulting in estimates for the fractional electrical distance of the 9-AA binding site of 0.56 and 0.22 in Cs+ and TMA+, respectively. This change may reflect a shift from predominantly 9-AA block in the presence of Cs+ to predominantly TMA+ block. The depth, but not the rate, of frequency-dependent block by QX-314 and 9-AA is reduced by internal TMA+. In addition, recovery from frequency-dependent block is not altered. Elevation of internal Na produces effects on 9-AA block qualitatively similar to those seen with TMA+. The results are consistent with a scheme in which the open channel blocking drugs, TMA (and Na) ions, and the inactivation gate all compete for a site or for access to a site in the channel from the intracellular surface. In addition, TMA ions decrease the apparent blocking rates of other drugs in a manner analogous to their inhibition of the inactivation process. Multiple occupancy of Na channels and mutual exclusion of drug molecules may play a role in the complex gating behaviors seen under these conditions.

A Study of Elasto-Plastic Response of Single Degree of Freedom System Using Artificial Ground Motions With Given Time-Frequency Characteristics

2010 ◽  
Author(s):  
Ichiro Ichihashi ◽  
Akira Sone ◽  
Arata Masuda ◽  
Daisuke Iba
Keyword(s):  
Ground Motion ◽  
Response Spectrum ◽  
Ground Motions ◽  
Frequency Characteristics ◽  
Earthquake Ground Motion ◽  
Time Frequency ◽  
Displacement Response ◽  
Earthquake Ground Motions ◽  
Design Response Spectrum ◽  
The Given

In this paper, a number of artificial earthquake ground motions compatible with time-frequency characteristics of recorded actual earthquake ground motion as well as the given target response spectrum are generated using wavelet transform. The maximum non-dimensional displacement of elasto-plastic structures excited these artificial earthquake ground motions are calculated numerically. Displacement response, velocity response and cumulative input energy are shown in the case of the ground motion which cause larger displacement response. Under the given design response spectrum, a selection manner of generated artificial earthquake ground motion which causes lager maximum displacement response of elasto-plastic structure are suggested.

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