The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform

Damian N Grant - One of the best experts on this subject based on the ideXlab platform.

  • response spectral matching of two Horizontal Ground Motion components
    Journal of Structural Engineering-asce, 2011
    Co-Authors: Damian N Grant
    Abstract:

    Accurate performance-based earthquake engineering analysis requires that engineering seismologists and structural analysts employ consistent characterizations of bidirectional seismic demand. In current design, the seismic demand is generally given as a geometric mean response spectrum, which does not give a direct measure of the maximum spectral demand for all possible orientations of the Ground Motion with respect to the axes of the structure. Although this may be appropriate for most applications, it is shown that for some structures in which the lateral-load resisting system is not decoupled into two orthogonal subsystems, the maximum rotated spectral demand (major axis demand) may be the most appropriate characterization of bidirectional seismic hazard. On the basis of this observation, a new program is developed for matching the major and minor axis spectra of two Horizontal Ground-Motion components simultaneously to two target spectra, using wavelets. The program, RspMatchBi, is based on the origin...

Dimitrios Vamvatsikos - One of the best experts on this subject based on the ideXlab platform.

M R Kianoush - One of the best experts on this subject based on the ideXlab platform.

  • dynamic analysis of flexible rectangular fluid containers subjected to Horizontal Ground Motion
    Earthquake Engineering & Structural Dynamics, 2013
    Co-Authors: S Hashemi, M M Saadatpour, M R Kianoush
    Abstract:

    In this paper, an analytical method is proposed to determine the dynamic response of 3-D rectangular liquid storage tanks with four flexible walls, subjected to Horizontal seismic Ground Motion. Fluid–structure interaction effects on the dynamic responses of partially filled fluid containers, incorporating wall flexibility, are accounted for in evaluating impulsive pressure. The velocity potential in which boundary conditions are satisfied is solved by the method of separation of variables using the principle of superposition. The impulsive pressure distribution is then computed. Solutions based on 3-D modeling of the rectangular containers are obtained by applying the Rayleigh–Ritz method using the vibration modes of flexible plates with suitable boundary conditions. Trigonometrical functions that satisfy boundary conditions of the storage tank such that the flexibility of the wall is thoroughly considered are used to define the admissible vibration modes. The analysis is then performed in the time domain. Moreover, an analytical procedure is developed for deriving a simple formula that evaluates convective pressure and surface displacements in a similar rigid tank. The variation of dynamic response characteristics with respect to different tank parameters is investigated. A mechanical model, which takes into account the deformability of the tank wall, is developed. The parameters of such a model can be obtained from developed charts, and the maximum seismic loading can be predicted by means of a response spectrum characterizing the design earthquake. Accordingly, a simplified but sufficiently accurate design procedure is developed to improve code formulas for the seismic design of liquid storage tanks. Copyright © 2013 John Wiley & Sons, Ltd.

Armen Der Kiureghian - One of the best experts on this subject based on the ideXlab platform.

  • simulation of orthogonal Horizontal Ground Motion components for specified earthquake and site characteristics
    Earthquake Engineering & Structural Dynamics, 2012
    Co-Authors: Sanaz Rezaeian, Armen Der Kiureghian
    Abstract:

    SUMMARY A method for generating an ensemble of orthogonal Horizontal Ground Motion components with correlated parameters for specified earthquake and site characteristics is presented. The method employs a parameterized stochastic model that is based on a time-modulated filtered white-noise process with the filter having time-varying characteristics. Whereas the input white-noise excitation describes the stochastic nature of the Ground Motion, the forms of the modulating function and the filter and their parameters characterize the evolutionary intensity and nonstationary frequency content of the Ground Motion. The stochastic model is fitted to a database of recorded Horizontal Ground Motion component pairs that are rotated into their principal axes, a set of orthogonal axes along which the components are statistically uncorrelated. Model parameters are identified for each Ground Motion component in the database. Using these data, predictive equations are developed for the model parameters in terms of earthquake and site characteristics and correlation coefficients between parameters of the two components are estimated. Given a design scenario specified in terms of earthquake and site characteristics, the results of this study allow one to generate realizations of correlated model parameters and use them along with simulated white-noise processes to generate synthetic pairs of Horizontal Ground Motion components along the principal axes. The proposed simulation method does not require any seed recorded Ground Motion and is ideal for use in performance-based earthquake engineering. Copyright © 2011 John Wiley & Sons, Ltd.

Sanaz Rezaeian - One of the best experts on this subject based on the ideXlab platform.

  • Stochastic Modeling and Simulation of Ground Motions for Performance-Based Earthquake Engineering
    2020
    Co-Authors: Sanaz Rezaeian
    Abstract:

    A site-based fully-nonstationary stochastic model for strong earthquake Ground Motion is developed. The model employs filtering of a discretized whit-noise process. Nonstationarity is achieved by modulating the intensity and varying the filter properties in time. The formulation has the important advantage of separating the temporal and spectral nonstationary characteristics of the process, thereby allowing flexibility and ease in modeling and parameter estimation. The model is fitted to recorded Ground Motions by matching a set of statistical characteristics, including the mean-square intensity, the mean zero-level up-crossing rate, and a measure of the bandwidth, all expressed as functions of time. These characteristics represent the evolving intensity and time-varying frequency content of the Ground Motion. Post-processing by a second filter assures zero residual velocity and displacement, and improves the match to response spectral ordinates for long periods.The proposed stochastic model is employed to develop a method for generating an ensemble of synthetic Ground Motion time-histories for specified earthquake and site characteristics. The stochastic model is fitted to a large number of recorded Ground Motions taken from the PEER NGA database. Strong Ground Motions recorded on firm Ground with source-to-site distance of at least 10 km are selected. Fitting to recorded Ground Motions results in sample observations of the stochastic model parameters. Using this sample, predictive equations are developed for the model parameters in terms of the faulting mechanism, earthquake magnitude, source-to-site distance and the site shear-wave velocity. For any specified set of these earthquake and site characteristics, sets of the model parameters are generated, which are in turn used in the stochastic model to generate an ensemble of synthetic Ground Motions. The resulting synthetic accelerations as well as corresponding velocity and displacement time-histories capture the main features of real earthquake Ground Motions, including the intensity, duration, spectral content, and peak values. Furthermore, the statistics of their resulting elastic response spectra closely agree with both the median and the variability of response spectra of recorded Ground Motions, as reflected in existing prediction equations based on the NGA database. The proposed method can be used in seismic design and analysis in conjunction with or instead of recorded Ground Motions.The method of Ground Motion simulation for specified earthquake and site characteristics is extended to simulate orthogonal Horizontal Ground Motion components. Two stochastic processes are considered, each representing one component. Assuming statistical independence between the underlying white-noise processes, the two Horizontal components are simulated on a set of orthogonal principal axes, along which the components are statistically uncorrelated. A database of principal component Ground Motion pairs is developed by rotating the as-recorded Horizontal Ground Motion component pairs into their principal axes. The stochastic model is fitted to the recorded Motions in the principal component database. Using the resulting sample observations for the model parameters, regression models are developed to empirically relate each model parameter to the earthquake and site characteristics. Correlations between parameters of the two Ground Motion components are empirically determined. Given earthquake and site characteristics, the results of this study allow one to generate realizations of correlated model parameters for the two Horizontal Ground Motion components. Each set of these model parameter realizations along with two statistically independent white-noise processes are used in the stochastic model to generate an orthogonal pair of Horizontal Ground Motion components along the principal axes. The simulated components, while being statistically independent, have overall characteristics, i.e., evolution of intensity and frequency content, that are similar to each other in the same way that the characteristics of a pair of real recorded Ground Motion components along their principal axes are similar. The simulated principal components may be rotated into any desired direction, such as the coordinate axes of a structure, through a simple orthogonal transformation.

  • simulation of orthogonal Horizontal Ground Motion components for specified earthquake and site characteristics
    Earthquake Engineering & Structural Dynamics, 2012
    Co-Authors: Sanaz Rezaeian, Armen Der Kiureghian
    Abstract:

    SUMMARY A method for generating an ensemble of orthogonal Horizontal Ground Motion components with correlated parameters for specified earthquake and site characteristics is presented. The method employs a parameterized stochastic model that is based on a time-modulated filtered white-noise process with the filter having time-varying characteristics. Whereas the input white-noise excitation describes the stochastic nature of the Ground Motion, the forms of the modulating function and the filter and their parameters characterize the evolutionary intensity and nonstationary frequency content of the Ground Motion. The stochastic model is fitted to a database of recorded Horizontal Ground Motion component pairs that are rotated into their principal axes, a set of orthogonal axes along which the components are statistically uncorrelated. Model parameters are identified for each Ground Motion component in the database. Using these data, predictive equations are developed for the model parameters in terms of earthquake and site characteristics and correlation coefficients between parameters of the two components are estimated. Given a design scenario specified in terms of earthquake and site characteristics, the results of this study allow one to generate realizations of correlated model parameters and use them along with simulated white-noise processes to generate synthetic pairs of Horizontal Ground Motion components along the principal axes. The proposed simulation method does not require any seed recorded Ground Motion and is ideal for use in performance-based earthquake engineering. Copyright © 2011 John Wiley & Sons, Ltd.