Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Distance, azimuth and site dependence of the frequency-dependent stochastic nonstationarity of the seismic acceleration at the 1989 Loma Prieta earthquake
AbstractThe strong motion records of the Loma Prieta earthquake of 17 October 1989 were analysed by the evolutionary power spectrum (EPS) method in order to investigate the nature of the stochastic nonstationarity. The EPSs show that the stochastic nonstationarity of the acceleration process is highly frequency-dependent. The great variation of the station soil conditions, distance and azimuth, allowed for the study of the influence of: firstly, the azimuth, i.e. the source's directivity and radiation pattern; secondly, the site, i.e. soil amplification and soil resonance effects; and finally, the distance, e.g. the path, on the stochastic nonstationarity. The EPSs illustrate the evolution of the wave fields with increasing distance and therefore the distance dependence of the nonstationarity. Also, the dependence of the evolutionary spectral shape on the incidence of the wave field and on the local and the intermediate soil conditions is demonstrated. Although the azimuth dependence is not so obvious, at some stations indications are present. In a simplified manner the nonstationarity can be explained by direct and surface wave subprocesses. Therefore, the EPSs are first interpreted by using these three wave types and then the results are discussed according to source, site and distance effects. For structural analysis purposes, each wave subprocess may be approximately modelled by a uniformly modulated stationary random process, a special kind of a nonstationary random process, and superposed to the total process.
Distance, azimuth and site dependence of the frequency-dependent stochastic nonstationarity of the seismic acceleration at the 1989 Loma Prieta earthquake
AbstractThe strong motion records of the Loma Prieta earthquake of 17 October 1989 were analysed by the evolutionary power spectrum (EPS) method in order to investigate the nature of the stochastic nonstationarity. The EPSs show that the stochastic nonstationarity of the acceleration process is highly frequency-dependent. The great variation of the station soil conditions, distance and azimuth, allowed for the study of the influence of: firstly, the azimuth, i.e. the source's directivity and radiation pattern; secondly, the site, i.e. soil amplification and soil resonance effects; and finally, the distance, e.g. the path, on the stochastic nonstationarity. The EPSs illustrate the evolution of the wave fields with increasing distance and therefore the distance dependence of the nonstationarity. Also, the dependence of the evolutionary spectral shape on the incidence of the wave field and on the local and the intermediate soil conditions is demonstrated. Although the azimuth dependence is not so obvious, at some stations indications are present. In a simplified manner the nonstationarity can be explained by direct and surface wave subprocesses. Therefore, the EPSs are first interpreted by using these three wave types and then the results are discussed according to source, site and distance effects. For structural analysis purposes, each wave subprocess may be approximately modelled by a uniformly modulated stationary random process, a special kind of a nonstationary random process, and superposed to the total process.
Distance, azimuth and site dependence of the frequency-dependent stochastic nonstationarity of the seismic acceleration at the 1989 Loma Prieta earthquake
Scherer, R.J. (Autor:in)
Engineering Structures ; 16 ; 470-484
01.01.1994
15 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
1989 Loma Prieta earthquake summary report
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