توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱SCALING OF LONG–TERM SEISMICITY IN ZAGROS, IRAN
نویسنده(ها): ، ، ،
اطلاعات انتشار: ششمین کنفرانس بین المللی زلزله شناسی و مهندسی زلزله، سال
تعداد صفحات: ۸
the long – term precursory scale increase y phenomenon is used for relating minor seismicity tomajor shallow earthquakes in zagros the y phenomenon involves an increase in the magnitude and rate of occurrence of minor earthquakes in an area near to the location of major event by the modeling of long term seismogenesis as a three –stage faulting process against a background of self–organized criticality the precursory scale increase y phenomenon can be inferred<\div>

۲assessment of uncertainty in seismic hazard analysis of dams using fuzzy mathematics
نویسنده(ها): ، ،
اطلاعات انتشار: سمپوزیوم برآورد عدم قطعیت در مهندسی سد، سال
تعداد صفحات: ۹
Our knowledge about earthquake, which is considered as a natural hazard, is highly conjugated with uncertainty. This uncertainty could be categorized into two classes. First, earthquake is a random event. It means that predicting the characteristics of the future seismic motion based on the current information is a matter of randomness, because there is not a comprehensive data from all influencing factors involved in generating seismic motion. From another point of view, not only there is very limited information, but also the available data are not precise. It means that our knowledge about earthquake is vague. This vagueness is not like randomness. For years, probability theory was the only mathematical framework for considering all kind of uncertainties. But by progressing of engineering knowledge and increasing the complexity of problems, it is necessary to study the influence of information fuzziness in the response of dynamic systems. Concerning with the problem of assessment of seismic hazard in dams, there are different sources of uncertainty. The data, upon which the seismicity of a region (i.e. earthquake catalogs and geological information) is determined, have different level of vagueness. For example, the accuracy of magnitude is not identical for all span of the catalog and on the other hand, the geological information is often qualitative and quantifying them brings a great deal of uncertainty. In the present paper, uncertainty of different parameters in magnitude probability density function is modeled by the help of fuzzy mathematics. In this regard, the effects of uncertainty of maximum and minimum magnitude in the catalog in addition to the effect of vagueness of earthquake magnitudes are studied separately. It is concluded that the influence of mmax uncertainty is negligible while this is not the case for m0 which is minimum or threshold magnitude and for magnitude of each event. There is also some kind of uncertainty for the seismicity parameter β which is due to the selection of estimation method. This uncertainty is crucial important and it is shown that it has a drastic influence on the magnitude distribution function. It is also demonstrated that the effect of different parameters’ uncertainty is considerable in the low and moderate magnitude range of the catalog.<\div>

۳Estimation of Site Effect in Zagros on the Basis of Horizontal–to–Vertical Spectral Ratio
نویسنده(ها): ، ،
اطلاعات انتشار: نهمین کنگره بین المللی مهندسی عمران، سال
تعداد صفحات: ۸
The consequences of recent earthquakes show the importance of site conditions. This means that, as well as source and path effects, the recorded data on the ground surface may be affected by site conditions. In general, the overall site effect is the site and crustal amplification functions combined with the nearsurfaceattenuation. Site amplification is estimated by the H\V ratio. Diminishing of the amplitude in the high frequency band may be modeled in terms of the Kappa factor. In this study, two datasets areconsidered for determining the H\V ratio and the Kappa factor. Using the best available information, recording sites are classified into two main geologic categories: rock (VS30>500m\s) and soil (VS30<500m\s). Correcting the records is done by using the modified wavelet de–noising method. In the frequency domain, this method can attenuate the noise in the whole frequency range of engineering interest while in the time domain it can detect and remove non– stationary noise. Using the modified wavelet de–noising method, it is possible to retrieve a large number of analog acceleration records which was not possible to correct using conventional methods of correction. A linear regression of the κ0v estimates compiled in this study indicates that κ0v about 0.027, 0.025 for the vertical component, for soil and rock site, respectively. Finally, after determining the Kappa factor and site amplification for the rock and soil sites, total site effect was estimated by multiplying two terms<\div>
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