Download or read book Simulating and Analyzing Artificial Non stationary Earthquake Ground Motions written by Robert F. Nau and published by . This book was released on 1980 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nonstationary Analysis and Simulation of Earthquake Ground Motions written by Gustavo Rodolfo Saragoni and published by . This book was released on 1972 with total page 207 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Non stationary Modelling and Simulation of Near source Earthquake Ground Motion written by P. S. Skjærbæk and published by . This book was released on 1996 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Simulating and Analyzing Artifical Non stationay Earthquake Ground Motions written by Robert F. Nau and published by . This book was released on 1980 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Stochastic Modeling and Simulation of Near Fault Ground Motions for Performance Based Earthquake Engineering written by Mayssa Dabaghi and published by . This book was released on 2014 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive parameterized stochastic model of near-fault ground motions in two orthogonal horizontal directions is developed. The proposed model uniquely combines several existing and new sub-models to represent major characteristics of recorded near-fault ground motions. These characteristics include near-fault effects of directivity and fling step; temporal and spectral non-stationarity; intensity, duration and frequency content characteristics; directionality of components, as well as the natural variability of motions for a given earthquake and site scenario. By fitting the model to a database of recorded near-fault ground motions with known earthquake source and site characteristics, empirical "observations" of the model parameters are obtained. These observations are used to develop predictive equations for the model parameters in terms of a small number of earthquake source and site characteristics. Functional forms for the predictive equations that are consistent with seismological theory are employed. A site-based simulation procedure that employs the proposed stochastic model and predictive equations is developed to generate synthetic near-fault ground motions at a site. The procedure is formulated in terms of information about the earthquake design scenario that is normally available to a design engineer. Not all near-fault ground motions contain a forward directivity pulse, even when the conditions for such a pulse are favorable. The proposed procedure produces pulselike and non-pulselike motions in the same proportions as they naturally occur among recorded near-fault ground motions for a given design scenario. The proposed models and simulation procedure are validated by several means. Synthetic ground motion time series with fitted parameter values are compared with the corresponding recorded motions. The proposed empirical predictive relations are compared to similar relations available in the literature. The overall simulation procedure is validated by comparing suites of synthetic ground motions generated for given earthquake source and site characteristics to the ground motion prediction equations (GMPEs) developed as part of phase 2 of the Next Generation Attenuation (NGA) program, (NGA-West2, see, e.g., Campbell and Bozorgnia, 2014). Comparison is made in terms of the estimated median level and variability of elastic ground motion response spectra. The use of synthetic motions in addition to or in place of recorded motions is desirable in performance-based earthquake engineering (PBEE) applications, particularly when recorded motions are scarce or when they are unavailable for a specified design scenario. As a demonstrative application, synthetic motions from the proposed simulation procedure are used to perform probabilistic seismic hazard analysis (PSHA) for a near-fault site. The analysis shows that the hazard at a near-fault site is underestimated when the ground motion model used does not properly account for the possibility of pulselike motions due to the directivity effect.

Download or read book Image based Modeling and Prediction of Non stationary Ground Motions written by Yildiz Dak Hazirbaba and published by . This book was released on 2015 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nonlinear dynamic analysis is a required step in seismic performance evaluation of many structures. Performing such an analysis requires input ground motions, which are often obtained through simulations, due to the lack of sufficient records representing a given scenario. As seismic ground motions are characterized by time-varying amplitude and frequency content, and the response of nonlinear structures is sensitive to the temporal variations in the seismic energy input, ground motion non-stationarities should be taken into account in simulations. This paper describes a nonparametric approach for modeling and prediction of non-stationary ground motions. Using Relevance Vector Machines, a regression model which takes as input a set of seismic predictors, and produces as output the expected evolutionary power spectral density, conditioned on the predictors. A demonstrative example is presented, where recorded and predicted ground motions are compared in time, frequency, and time-frequency domains. Analysis results indicate reasonable match between the recorded and predicted quantities.

Download or read book Analysis and Modeling of Nonstationary Ground Motion Coherency written by Habeeb Fadhel Abbas and published by . This book was released on 2018 with total page 550 pages. Available in PDF, EPUB and Kindle. Book excerpt: Conventional coherency models which rely on Fourier-based tools do not consider the nonstationary character of ground motions. Accurate understanding for nonstationary coherency can motivate accurate modeling and simulation of spatially incoherent ground motions. In this work, a nonstationary ground motion coherency analysis and modeling are performed using wavelet analysis and relevance vector machine regression. To perform the analysis, earthquake ground motion data from four events recorded at dense seismograph SMART-1 array in north-south and east-west horizontal directions are used to investigate the lagged coherency behavior. Continuous Wavelet Transform (CWT) is used to compute the nonstationary lagged coherency that characterizes the space-time variation of seismic ground motion. Complex Morlet wavelet is chosen as the mother wavelet as it is quite well localized in both time and frequency space. Wavelet transform with significance tests have been used to distinguish the strong motions S-wave window with the corresponding frequency band. Based on these S-wave windows, wavelet transform is used to compute the nonstationary lagged coherency of ground motions. A homogeneous isotropic field is assumed. Lagged coherency behavior with frequency, distance, and time is examined. It is shown that the lagged coherency is not constant and evolves with time. The results implied that the lagged coherency on uniform soil depends mainly on time, frequency, and separation distance. The wavelet transform results from the four events are compared with two conventional lagged coherency models. The comparisons showed the difference between the evolving behavior of the lagged coherency with the stationary prediction of the conventional coherency models. To perform the modeling, Relevance Vector Machines (RVM) regression is used to develop a model for the nonstationary lagged coherency that characterizes the space-time variation of seismic ground motion. Earthquake ground motion data from dense seismograph SMART-1 array is used to determine the lagged coherency model in the north-south and the first principal directions. Frequencies and separation distances for the estimated nonstationary lagged coherency represent the trained data for the RVM set to construct the model and estimate the lagged coherency values. The RVM model results are compared with two conventional lagged coherency models. The proposed model does not require a fixed parametric functional form; it can estimate the lagged coherency for different separation distances at different time instants and frequencies. Finally, in this study, the developed nonstationary lagged coherency model is used to generate incoherent artificial spatial ground motions. The simulation of ground motion stochastic process is performed using specified evolutionary power and cross spectral densities. The simulation results are compared with generated ground motion using conventional stationary coherency model. The phase and phase difference from both simulations are compared to show the difference between the results.

Download or read book Wavelet Analyses for Seismic Ground Motion Simulation and Stochastic Site Response written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The response of soil masses during an earthquake is governed by the characteristics of the ground motions and the soil material properties. The ground motions generated during earthquakes are random and nonstationary with respect to both amplitude and frequency. Different methods of analysis for time-frequency characteristics of the ground motions have been reviewed and the merits and disadvantages of each are explained. The methods considered here are: Fourier Transform (FT), Short Term Fourier Transform (STFT), Wigner-Ville (WV) Distribution, Hilbert-Huang Transform (HHT), and Wavelet Transform (WT). WT method with a modified version of Littlewood-Paley mother wavelet is found most suitable to analyze the nonstationary characteristics of the seismic ground motion. This method is used to identify some of the nonlinear and nonstationary characteristics of the ground motions recorded during some important earthquakes, namely Northridge-California 1994, Kocaeli-Turkey 1999, and Chi-Chi-Taiwan, 1999. The effect of site distance and site softening on the ground motion characteristics are studied. The information on redistribution of the energy among various frequency ranges as well as its temporal variation is revealed. Responses of Clay and Sand sites with different stiffness-thickness-saturation combinations to different excitations are studied with the use of a computer code for nonlinear analysis of site response (Cyclic1D) and wavelet analysis. Observations for amplification, deamplification, and pore pressure build up are given in both time and frequency domains. A wavelet based formulation to generate earthquake ground motions is also developed. This method uses a seed acceleration history and a selected design response spectrum to produce many motions that retain the main time-frequency characteristics of the original motion, yet are all different from each other. Finally, a wavelet based method to evaluate non-stationary stochastic response of a soil site, idea.

Download or read book NUREG CR written by U.S. Nuclear Regulatory Commission and published by . This book was released on 1980 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Analog Simulation of Earthquake Motions written by Paul H. Wirsching and published by . This book was released on 1968 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ground Motion Simulation Validation Based on Loss Metrics written by Poojitha Shashi and published by . This book was released on 2017 with total page 59 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effect of the earthquake ground motion parameters on the probabilistic loss estimation of buildings is the major interest of this study. For the seismic performance assessment, real ground motion records from the past earthquakes are required. Estimation of repair costs in future earthquakes is the major component for seismic loss analysis. This study addresses the sensitivity of the statistical characteristics of ground motions contributing to the building loss. Among these characteristics are the ground-shaking intensity (Arias Intensity), duration, and frequency at the middle of strong-shaking phase of the ground motion. These parameters are vital in determining the seismic response of the building structure. A fine study on the sensitivity of the seismic response and corresponding loss of the building structure to ground motions model parameters is carried out using Performance-based Earth- quake Engineering and Performance Assessment Computational Tool, respectively. But due to the scarcity of moderate to large earthquakes, the real records fail to match the required characteristics of motions, as there are insufficient set of data available for analysis to be carried out. Even, the of technique scaling ground motions results in overall unrealistic properties. This has led to the simulation of ground motions which will provide the additional and hopefully accurate predicted information on characteristics of the moderate to large earthquakes. Hence, a fully non-stationary stochastic model for strong earthquake ground motion model is considered which employs the statistical characteristics (waveform parameters) as model parameters matched with those of identified for a large sample of recorded ground motions for specified earthquake and site characteristics, to deliver simulated ground motions to examine the building loss metrics, which depends on the uncertainties in various analysis process starting from obtaining Intensity Measure (IM), Demand parameters (EDPs) to the repair cost estimates. From the predictive equations, specified earthquake and site characteristics results in the model parameters.Further, the validity of simulated ground motion time series representing the real ground shaking during future earthquakes is a crucial step. This study employs the hybrid broad- band ground motion simulation applied simulations to validate against the real records. With the help of hybrid approach, making use of wave propagation phenomena and site response characterization, effort has been taken for validation of these simulated ground motions is conducted for the sensitivity of seismic response and loss for these simulated ground motions.

Download or read book Image based Modeling and Prediction of Non stationary Ground Motions written by Yildiz Dak Hazirbaba (‡e author) and published by . This book was released on 2015 with total page 133 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nonlinear dynamic analysis is a required step in seismic performance evaluation of many structures. Performing such an analysis requires input ground motions, which are often obtained through simulations, due to the lack of sufficient records representing a given scenario. As seismic ground motions are characterized by time-varying amplitude and frequency content, and the response of nonlinear structures is sensitive to the temporal variations in the seismic energy input, ground motion non-stationarities should be taken into account in simulations. This paper describes a nonparametric approach for modeling and prediction of non-stationary ground motions. Using Relevance Vector Machines, a regression model which takes as input a set of seismic predictors, and produces as output the expected evolutionary power spectral density, conditioned on the predictors. A demonstrative example is presented, where recorded and predicted ground motions are compared in time, frequency, and time-frequency domains. Analysis results indicate reasonable match between the recorded and predicted quantities.

Download or read book Ground Motion Simulations written by Lynne Schleiffarth Burks and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Engineers use earthquake ground motions for a variety of reasons, including seismic hazard assessment, calibration of ground motion prediction equations (GMPEs), and input to nonlinear response history analysis. These analyses require a significant number of ground motions and for some scenarios, such as earthquakes with large magnitudes and short distances, it may be difficult to obtain a sufficient number of ground motion recordings. When sufficient recordings do not exist, engineers modify available recordings using scaling or spectrum matching, or they use ground motion simulations. Ground motion simulations have existed for decades, but recent advances in simulation methods due to improved source characterization and wave propagation, coupled with increased computing power, have increased potential benefits for engineers. But before simulations can be used in engineering applications, simulations must be accessible and consistent with natural observations. This dissertation contributes to the latter issue, and it investigates the application of simulations to specific engineering problems. The Southern California Earthquake Center (SCEC) Broadband Platform (BBP) is an open-source software distribution that enables third-party users to simulate ground motions using research code contributed by model developers. Because the BBP allows users to compute their own simulations with little knowledge of the underlying implementation and it ensures that all calculations are reproducible, it is extremely valuable for simulation validation and engineering applications. In this dissertation, the BBP is evaluated as a simulation generation tool from an engineering perspective. Ground motions are simulated to study parameters of engineering interest, such as high-frequency variability, near-fault ground motions, and local site response. Though some parameters need further development, such as site response (which is currently implemented using simple empirical amplification), the BBP proves to be an effective tool for facilitating these types of engineering studies. This dissertation proposes a simulation validation framework based on simple and robust proxies for the response of more complicated structures. We compile a list of proxies with robust empirical models that are insensitive to changes in earthquake scenario and do not rely on extrapolation for rarely observed events. Because predictions of these proxies are reliable under a variety of earthquake events, we can confidently compare them with simulations. The proposed proxies include correlation of epsilon across periods, ratio of maximum to median response across horizontal orientations, and ratio of inelastic to elastic displacement. The validation framework is applied to example simulations and successfully exposes some parameters that need work, such as variability and correlation of spectral acceleration. Finally, this dissertation investigates the application of simulations to response history analysis and fling-step characterization. A 3D nonlinear structural model is analyzed using recordings and simulations with similar elastic response spectra. The structural performance and resulting design decisions are similar, indicating that simulations are effective for response history analysis subject to certain conditions. To investigate fling-step, we extract fling pulses from a large set of simulations. Extracted fling properties such as amplitude and period are then compared to specially-processed recordings and relevant empirical models for surface displacement and pulse period. Reasonably good agreement is found between simulations, recordings, and empirical models. In general, ground motion simulations are found to be an effective alternative or supplement to recordings in several engineering applications. Because simulation methods are still developing, this work is not intended as an evaluation of existing methods, but rather as a development of procedures that can be used in ongoing work.

Download or read book Non ergodic Probabilistic Seismic Hazard Analysis and Spatial Simulation of Variation in Ground Motion written by Melanie Anne Walling and published by . This book was released on 2009 with total page 526 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Estimation of Response Spectra and Simulation of Nonstationary Earthquake Ground Motions written by Fabio Sabetta and published by . This book was released on 1995 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Stochastic Model for Earthquake Ground Motion Using Wavelet Packets written by Yoshifumi Yamamoto and published by Stanford University. This book was released on 2011 with total page 329 pages. Available in PDF, EPUB and Kindle. Book excerpt: For performance-based design, nonlinear dynamic structural analysis for various types of input ground motions is required. Stochastic (simulated) ground motions are sometimes useful as input motions, because unlike recorded motions they are not limited in number and because their properties can be varied systematically to study the impact of ground motion properties on structural response. This dissertation describes an approach by which the wavelet packet transform can be used to characterize complex time-varying earthquake ground motions, and it illustrates the potential benefits of such an approach in a variety of earthquake engineering applications. The proposed model is based on Thr´ainsson and Kiremidjian (2002), which use Fourier amplitudes and phase differences to simulate ground motions and attenuation models to their model parameters. We extend their model using wavelet packet transform since it can control the time and frequency characteristic of time series. The time- and frequency-varying properties of real ground motions can be captured using wavelet packets, so a model is developed that requires only 13 parameters to describe a given ground motion. These 13 parameters are then related to seismological variables such as earthquake magnitude, distance, and site condition, through regression analysis that captures trends in mean values, standard deviations and correlations of these parameters observed in a large database of recorded strong ground motions. The resulting regression equations then form a model that can be used to predict ground motions for a future earthquake scenario; this model is analogous to widely used empirical ground motion prediction models (formerly called "attenuation models") except that this model predicts entire time series rather than only response spectra. The ground motions produced using this predictive model are explored in detail, and are shown to have elastic response spectra, inelastic response spectra, durations, mean periods, etc., that are consistent in both mean and variability to existing published predictive models for those properties. That consistency allows the proposed model to be used in place of existing models for probabilistic seismic hazard analysis (PSHA) calculations. This new way to calculate PSHA is termed "simulation-based probabilistic seismic hazard analysis" and it allows a deeper understanding of ground motion hazard and hazard deaggregation than is possible with traditional PSHA because it produces a suite of potential ground motion time histories rather than simply a distribution of response spectra. The potential benefits of this approach are demonstrated and explored in detail. Taking this analysis even further, this suite of time histories can be used as input for nonlinear dynamic analysis of structures, to perform a risk analysis (i.e., "probabilistic seismic demand analysis") that allows computation of the probability of the structure exceeding some level of response in a future earthquake. These risk calculations are often performed today using small sets of scaled recorded ground motions, but that approach requires a variety of assumptions regarding important properties of ground motions, the impacts of ground motion scaling, etc. The approach proposed here facilitates examination of those assumptions, and provides a variety of other relevant information not obtainable by that traditional approach.

Download or read book Influence Quantification of Non stationary Frequency Content of Earthquake Ground Motions to Performance based Earthquake Engineering written by Alessandro Margnelli and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: