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۱Design Earthquake Based on Probabilistic Seismic Hazard Analyses
نویسنده(ها):
اطلاعات انتشار: سومین کنفرانس ملی بهسازی و مقاوم سازی ایران، سال
تعداد صفحات: ۵
The solutions of many earthquake engineering problems involve dynamic analyses using time series. It is often desirable to base the selection of such motions on a probabilistic estimate of the seismic hazard. Probabilistic seismic hazard analyses (PSHA) is a technique for estimating the annual rate of exceedance of a specified ground motion at a site due to known and suspected earthquake sources. The disadvantage of PSHA is that the concept of a “design earthquake” is lost; i.e. there is no single event that for design or retrofit. The relative contributions of the various sources to the total seismic hazard are determined as a function of their occurrence rates and their ground–motion potential. This study describes a method wherein a design earthquake can be obtained that accurately represents the uniform Fourier hazard spectrum from a PSHA. Seismic hazard can be deaggregated to show the contribution by magnitude, distance and ground motion uncertainty.<\div>

۲Design Earthquake Based on Deaggregation of Seismic Hazard
نویسنده(ها):
اطلاعات انتشار: هشتمین کنگره بین المللی مهندسی عمران، سال
تعداد صفحات: ۷
The disadvantage of probabilistic seismic hazard analysis is that the concept of a “design earthquake” is lost; i.e. there is no single event that for design or retrofit. The relative contributions of the various sources to the total seismic hazard are determined as a function of their occurrence rates and their ground–motion potential. This study describes a method wherein a design earthquake can be obtained that accurately represents the uniform Fourier hazard spectrum from a PSHA. If different seismic sources dominate the hazard at different frequencies, then contributions to the hazard come from significantly different magnitudes, distances, and ε’s. In this case, a single design earthquake is not appropriate and it is necessary to represent design earthquake for short and long periods.<\div>

۳Calculation Stochastic Input energy Spectra from Frequency Amplitude Spectra
نویسنده(ها):
اطلاعات انتشار: هشتمین کنگره بین المللی مهندسی عمران، سال
تعداد صفحات: ۷
A theoretically relation is presented between the seismological Fourier amplitude spectrum and the elastic input energy spectrum. The presented relationship provides an important basis for better understanding of the relationship between input energy spectra and other seismological variables, such as magnitude, focal distance, path, and site effects. In this study, the contribution of these sources of variability to the uncertainty in input energy is examined using stochastic analysis, Monte Carlo simulation, to compare the effect of these earthquake ground motion parameters. Analytical results show that the influence of earthquake magnitude, focal distance, and soil condition are important for the shape and amplitude of input energy spectra.<\div>

۴Earthquake duration effect on the nonlinear response of MDOF system using a new version of Incremental Dynamic Analysis (IDA)
نویسنده(ها): ، ،
اطلاعات انتشار: پنجمین کنگره ملی مهندسی عمران، سال
تعداد صفحات: ۷
In this article we introduce a new version of Incremental Dynamic Analysis (IDA) by which the effect of earthquake duration on the nonlinear dynamic response of the structure seems to be more obvious. We believe that the input energy of earthquakes is a better Intensity Measure (IM) than the spectral acceleration in first mode of the structure vibration (Sa(T1,5%)) for the study of duration effects. We used artificial acceleration time–histories simulated by the specific barrier model modified slightly for this study as well as real records apropriately selcted. Results confirm our proposed aproach.<\div>

۵Sensitivity analysis of steel frame considering uncertainty
اطلاعات انتشار: نهمین کنگره بین المللی مهندسی عمران، سال
تعداد صفحات: ۵
One of the challenging issues in modern civil engineering analysis is the typically large number of random quantities defining the input and system parameters. One approach to making such problems tractable is to identify the most important sources of uncertainty. The influence of uncertainties of input and system parameters on the uncertainty of system response expressed by mathematical models is studied using sensitivity and uncertainty analyses. The stochastic sensitivity analysis will be carried out with the aim of assessing the relative sensitivity of the random variability of a monitored event to the random variability of individual input variables. The objective of the study is to assessment the influence of initial imperfections and excitation uncertainties on the response of a single storey steel plane frame. The influence of the variance of initial imperfections and excitation uncertainties on the variance of the response was calculated by Monte Carlo based procedure<\div>

۶Probabilistic Quantification of Incremental Dynamic Analysis Results
نویسنده(ها): ،
اطلاعات انتشار: هشتمین کنگره ملی مهندسی عمران، سال
تعداد صفحات: ۶
Incremental Dynamic Analysis (IDA) is a parametric analysis method that has recently emerged in several different forms to estimate more thoroughly structural performance under seismic load. It involves subjecting a structural model to one or more ground motion records. This method considers both inherent randomness and model uncertainty, so it used to probabilistic analysis of structures at high seismic loading. The objective of this study is to improve efficient, but accurate procedures for probabilistic analysis of nonlinear seismic behavior of structure. According to the three–parameter Log–normaldistribution more rationally describe maximum story drift ratio at a higher value of spectral acceleration. The traditional method based on two–parameter Log–normal distribution is compared with the presented procedure based on three–parameter Log–normal distribution on analytical data. Improvement in the probabilistic estimation of maximum story drift ratio demand are illustrate with a SAC–9 story, moment resisting frame building exposed to a set of 20 ground motion.<\div>

۷Assessment of the Effect of Content Frequency of Ground Motions on Input Energy
نویسنده(ها): ،
اطلاعات انتشار: هشتمین کنگره ملی مهندسی عمران، سال
تعداد صفحات: ۸
Input Energy that produced by ground motions in structures, is an important factor in structural analysis. In this study, wavelet transform is used as one of the useful tools in engineering for evaluating input energy and its effect on structure. Ground motion with specified frequency content are decomposed intodifferent signals with the help of wavelet transform that each new signal covers specified frequency content of the main signal. As a result of this transform, input energy as one of the most important factors that effects on structural damage is studying using different signals with different frequency bandwidth.Input energy of 5–story structure under different near to far distance ground motions are studied using this procedure. The results illustrated the relationship of input energy and frequency content of earthquakes.<\div>

۸An Artificial Statistical Method to Estimate Seismicity Parameter from Incomplete Earthquake Catalogs, a Case Study in Metropolitan Tehran, Iran
اطلاعات انتشار: Scientia Iranica، بيست و دوم،شماره۲، ۲۰۱۵، سال
تعداد صفحات: ۱۰
Uncertainties in earthquake catalogs, earthquake recurrence parameters, and in the variation of ground motion parameters are often considered in the evaluation of seismic hazard analysis. The purpose of this study is to develop an artificial statistical procedure based on Bayes’ formulation and weighted bootstrap sampling to estimate seismicity parameter (b–value of the Gutenberg–Richter law) from both historical and instrumental data in a given region. The procedure allows for uncertainty in the period of completeness, and assigns different weights to historical seismicity as compared to instrumental seismicity. Variation of seismicity within seismic sources is allowed with this procedure. This variation generalizes the condition of spatially homogeneous seismicity within seismic sources and permits accurate representation of historical seismicity. As a case study, the earthquake catalog of the greater Tehran, Iran is considered to estimate seismicity parameters as well as probabilistic seismic hazard analysis (PSHA) using the proposed procedure, and then the results are compared with those obtained from a conventional PSHA method. This comparison confirms the applicability of the procedure used in this study.
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