This study addresses the topic of the spatial variation of seismic ground motions as evaluated from data recorded at dense instrument arrays. It concentrates on the stochastic description of the spatial variation, and focuses on spatial coherency. The estimation of coherency from recorded data and its interpretation are presented. Some empirical and semi-empirical coherency models are described, and their validity and limitations in terms of physical causes discussed. An alternative approach that views the spatial variation of seismic motions as deviations in amplitudes and phases of the recorded data around a coherent approximation of the seismic motions is described. Simulation techniques for the generation of artificial spatially variable seismic ground motions are also presented and compared. The effect of coherency on the seismic response of extended structures is highlighted. This review article includes 133 references. @DOI: 10.1115/1.1458013#

http://www.pages.drexel.edu/~zervaa/Zerva&Zervas.pdf

Spatial variation of seismic ground motions: An overview

Design strategies of viscous dampers for seismic protection of building structures: A review

Optimal design and seismic performance of tuned mass damper inerter (TMDI) for structures with nonlinear base isolation systems

Results of stationary and transient response analyses of the Golden Gate suspension bridge, and the New River Gorge and Cold Spring Canyon deck arch bridges, to a general spatially varying earthquake ground motion (SVEGM) model are presented. The results are compared with responses computed using identical and delayed excitations. The use of identical excitations is in general unacceptable for these long-span bridges, and the use of delayed excitations is acceptable only for the longitudinal response of short arch bridges. Surprisingly, the transient lateral displacements of the suspension bridge center span significantly overshoot the corresponding stationary displacements for the filtered Kanai-Tajimi excitation power spectrum; this spectrum may therefore be unsuitable for analyzing very flexible structures. The qualitative effects of SVEGM on stationary and transient force responses are found to be similar.

Response of long-span bridges to spatially varying ground motion

Accurate and highly efficient algorithms for structural stationary/non-stationary random responses

A new response spectrum method is developed for seismic analysis of linear multi-degree-of-freedom, multiply supported structures subjected to spatially varying ground motions. Variations of the ground motion due to wave passage, loss of coherency with distance and variation of local soil conditions are included. The method is based on fundamental principles of random vibration theory and properly accounts for the effects of correlation between the support motions as well as between the modes of vibration of the structure.

Ansgar Neuenhofer

Papers

Response spectrum method for multi‐support seismic excitations

Seismic Random-Vibration Analysis of Multisupport-Structural Systems

Discussion of "Seismic Random-Vibration Analysis of Multisupport-Structural Systems"