1st Edition

Spatial Variation of Seismic Ground Motions Modeling and Engineering Applications

By Aspasia Zerva Copyright 2009
    486 Pages 174 B/W Illustrations
    by CRC Press

    The spatial variation of seismic ground motions denotes the differences in the seismic time histories at various locations on the ground surface. This text focuses on the spatial variability of the motions that is caused by the propagation of the waveforms from the earthquake source through the earth strata to the ground surface, and it brings together the various aspects underlying this complicated phenomenon.

    Topics covered include:

    • Evaluation of the spatial variability from seismic data recorded at dense instrument arrays by means of signal processing techniques
    • Presentation of the most widely used parametric coherency models, along with brief descriptions of their derivation
    • Illustration of the causes underlying the spatial variation of the motions and its physical interpretation
    • Estimation of seismic ground-surface strains from single station data, spatial array records, and analytical methods
    • Introduction of the concept of random vibrations as applied to discrete-parameter and continuous structural systems on multiple supports
    • Generation of simulations and conditional simulations of spatially variable seismic ground motions
    • Overview of the effects of the spatial variability of seismic motions on the response of long structures, such as pipelines, bridges and dams, with brief descriptions of select seismic codes that incorporate spatial variability issues in their design recommendations

    This book may serve as a tutorial and/or reference for graduate students, researchers and practicing engineers interested in advancing the current state of knowledge in the analysis and modeling of the spatial variation of the seismic ground motions, or utilizing spatially variable excitations in the seismic response evaluation of long structures.

    Introduction

    Stochastic estimation of spatial variability

    Basic definitions

    Stochastic processes

    Bi-variate stochastic processes

    Coherency

    Multi-variate stochastic processes and stochastic fields

    Parametric modeling of spatial variability

    Parametric power spectral densities

    Early studies on spatial variability

    Dependence of coherency on physical parameters

    Parametric coherencymodeling

    Parametric cross spectrum modeling

    Physical characterization of spatial variability

    Frequency-wavenumber (F-K) spectra

    Amplitude and phase variability

    Seismic ground-surface strains

    Semi-empirical estimation of the propagation velocity

    Estimation of the surface strain field

    Accuracy of single-station strain estimation

    Incoherence vs propagation effects in surface strains

    Displacement gradient estimation from array data

    Considerations in the estimation of seismic ground strains

    Random vibrations for multi-support excitations

    Introduction to random vibrations

    Discrete-parameter systems

    Distributed-parameter systems

    Analysis of rms lifeline response

    Additional random vibration considerations

    Simulations of spatially variable ground motions

    Simulation of random processes

    Simulation of random fields

    Simulation ofmulti-variate stochastic vector processes

    Conditionally simulated ground motions

    Conditional simulation of random processes

    Processing of simulated acceleration time series

    Example applications

    Engineering Applications

    Large, mat, rigid foundations

    Dams

    Suspension and cable-stayed bridges

    Highway bridges

    Some concluding remarks

    References

    Biography

    Aspasia Zerva