共查询到20条相似文献，搜索用时 15 毫秒
1.
IntroductionAccordingtoEarthquakeResistanceandDisasterReductionLawforthePeoplesRepublicofChina,twomethodsareadoptedforseismicdesignoftheconstructionprojectsinChina.Forkeyprojectsandtheprojectseasytocauseserioussecondarydisasters,seismicsafetyevaluationsmustbecarriedout.Andbasedontheresults,seismicfortificationstandardsaredeterminedtomakeseismicdesign.Forgeneralindustrialandcivilbuildings,seismicdesignsarecarriedoutaccordingtotheseismicfortificationstandardsstipulatedbyseismiczonationmap(Ch… 相似文献
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Conventional design practice aims at obtaining optimal estimates of floods with specified exceedance probabilities. Such estimates are, however, known on the average to be exceeded more frequently than expected. Alternatively, methods focusing on the expected exceedance probability can be used. Two different methods are considered here; the first is based on the sample distribution of true exceedance probabilities. The second is a Bayesian analogue using the likelihood function and a noninformative prior to describe the variability of exceedance probabilities. Appropriate analytical solutions are presented in both cases using the partial duration series approach. 相似文献
4.
P. F. Rasmussen D. Rosbjerg 《Stochastic Environmental Research and Risk Assessment (SERRA)》1991,5(1):1-16
Conventional design practice aims at obtaining optimal estimates of floods with specified exceedance probabilities. Such estimates are, however, known on the average to be exceeded more frequently than expected. Alternatively, methods focusing on the expected exceedance probability can be used. Two different methods are considered here; the first is based on the sample distribution of true exceedance probabilities. The second is a Bayesian analogue using the likelihood function and a noninformative prior to describe the variability of exceedance probabilities. Appropriate analytical solutions are presented in both cases using the partial duration series approach. 相似文献
5.
Probabilistic risk assessment of contaminant transport in groundwater and vapour intrusion following remediation of a contaminant source 总被引：1，自引：1，他引：0
Kevin G. Mumford Nizar Mustafa Jason I. Gerhard 《Stochastic Environmental Research and Risk Assessment (SERRA)》2016,30(3):1017-1031
Community-scale simulations were performed to investigate the risk to groundwater and indoor air receptors downgradient of a contaminated site following the remediation of a long-term source. Six suites of Monte Carlo simulations were performed using a numerical model that accounted for groundwater flow, reactive solute transport, soil gas flow, and vapour intrusion in buildings. The model was applied to a three-dimensional, community-scale (250 m × 1000 m × 14 m) domain containing heterogeneous, spatially correlated distributions of the hydraulic conductivity, fraction of organic carbon, and biodegradation rate constant, which were varied between realizations. Analysis considered results from both individual realizations as well as the suite of Monte Carlo simulations expressed through several novel, integrated parameters, such as the probability of exceeding a regulatory standard in either groundwater or indoor air. Results showed that exceedance probabilities varied considerably with the consideration of biodegradation in the saturated zone, and were less sensitive to changes in the variance of hydraulic conductivity or the incorporation of heterogeneous distributions of organic carbon at this spatial scale. A sharp gradient in exceedance probability existed at the lateral edges of the plumes due to variability in lateral dispersion, which defined a narrow region of exceedance uncertainty. Differences in exceedance probability between realizations (i.e., due to heterogeneity uncertainty) were similar to differences attributed to changes in the variance of hydraulic conductivity or fraction of organic carbon. Simulated clean-up times, defined by reaching an acceptable exceedance probability, were found to be on the order of decades to centuries in these community-scale domains. Results also showed that the choice of the acceptable exceedance probability level (e.g., 1 vs. 5 %) would likely affect clean up times on the order of decades. Moreover, in the scenarios examined here, the risk of exceeding indoor air standards was greater than that of exceeding groundwater standards at all times and places. Overall, simulations of coupled transport processes combined with novel spatial and temporal quantification metrics for Monte Carlo analyses, provide practical tools for assessing risk in wider communities when considering site remediation. 相似文献
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Influence of weak trends on exceedance probability 总被引：1，自引：0，他引：1
Studying the hypothetical case of a trend superimposed on a random stationary variable, we highlight the strong influence
of possible non-stationarities on exceedance probability. After a general outline, the subject is analytically developed using
the Gumbel distribution, emphasizing the quick increase of the exceedance probability over time in the presence of weak rising
trends, and its sensitive underestimation where the non-stationarity goes unnoticed or is considered negligible. Finally the
work is applied to hydrological series of rainfall and river flow.
Received: March 27, 1997 相似文献
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工程场地的设计地震动参数,目前多用概率地震危险性分析的方法给出。场地的地震基本烈度以设计基准期T=50年、加速度超越概率P=0.1的标准确定。本文根据广东省数地地震危险性分析结果结合我国常见的砖混结构的地震动参数的优化决策,认为上述标准宜取为T=50年、P=0.05—0.1。 相似文献
8.
A. Porporato L. Ridolfi 《Stochastic Environmental Research and Risk Assessment (SERRA)》1998,12(1):1-14
Studying the hypothetical case of a trend superimposed on a random stationary variable, we highlight the strong influence
of possible non-stationarities on exceedance probability. After a general outline, the subject is analytically developed using
the Gumbel distribution, emphasizing the quick increase of the exceedance probability over time in the presence of weak rising
trends, and its sensitive underestimation where the non-stationarity goes unnoticed or is considered negligible. Finally the
work is applied to hydrological series of rainfall and river flow.
Received: March 27, 1997 相似文献
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湖南中强地震活动地区Ⅱ类场地放大效应研究 总被引：3，自引：1，他引：2
利用工程场地地震安全性评价工作中大量实际钻孔和土工实验资料,建立了实际工程场地模型,在50年超越概率为63%、10%、2%共3种地震动输入下,采用SHAKE91和ELSSRA两种等效线性化方法,研究了湖南省Ⅱ类场地土层的放大效应.计算结果表明:湖南省50年超越概率10%的场地效应放大因子为1.30,若使用<中国地震动参数区划图(GB18306-2001)>认定的1.25系数,将低估湖南中强地震活动地区的场地放大效应.湖南省50年超越概率63%、10%、2%这3个设定水准的场地效应放大因子满足1.10:1.00:0.95的关系.这些结果有益于为湖南省提供更为合理的抗震设防标准. 相似文献
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Probabilistically controlled design values of the nonlinear seismic response of reinforced concrete frames are obtained using a method previously proposed by the authors. The method allows to calculate conservative design values characterized by a predefined non‐exceedance probability, using a limited number of spectrum‐fitting generated accelerograms. Herein the method is applied to elastic‐strain hardening single degree of freedom systems representative of RC framed structures and is then assessed with reference to four reinforced concrete model frames designed according to EC8. The frames are characterized by different natural periods and aspect ratios. The results, compared with those obtained applying current EC8 recommendations, show the effectiveness of the proposed method. EC8 provides for design values of the seismic response of a structure with a nonlinear behavior computed as the mean value of the responses to seven accelerograms or as the maximum value of the responses to three accelerograms. These two criteria lead to design values characterized by very different and uncontrolled non‐exceedance probability levels, while the proposed method allows the analyst to directly control the non‐exceedance probability level of the calculated design values. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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地震危险性概率分析(PSHA)是目前最广泛应用于地震灾害与风险性评估的方法。然而它在计算中却存在着一个错误:把强地面运动衰减关系(一个函数)的条件超越概率等同于强地面运动误差(一个变量)的超越概率。这个错误导致了运用强地面运动误差(空间分布特征)去外推强地面运动的发生(时间分布特征)或称之为遍历性假设,同时也造成了对PSHA理解和应用上的困难。本文推导出新的灾害计算方法(称之为KY-PSHA)来纠正这种错误。 相似文献
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C. C. Smart 《地球表面变化过程与地形》1988,13(3):271-288
Combination of a conduit flow law with the exceedance probability of stream discharge allows the estimation of the exceedance probability of water level in a simple conduit aquifer. The probability of water levels higher than available relief is interpreted as the probability of surface as opposed to underground runoff. Very high probability of surface runoff implies a fluvial environment, whereas very low probabilities define a mature karst or ‘holokarst’, Intermediate probabilities identify ‘fluviokarst’. Overflow probability depends on available relief, mean discharge, and especially conduit radius. Growth rate of the underground conduit depends on saturation deficit which thus controls the rate of evolution of the fluvial landscape, through fluviokarst to holokarst. However, variations of discharge and sedimentation through time can cause dramatic reversion of karst drainage into less mature states. Landscapes experiencing such periodic rejuvenation will have a confused morphology. A functional definition of landscape may be more objective and pertinent than arbitrary interpretation of form. 相似文献
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A probabilistic approach to estimate maximum inelastic displacement demands of single‐degree‐of‐freedom (SDOF) systems is presented. By making use of the probability of exceedance of maximum inelastic displacement demands for given maximum elastic spectral displacement and the mean annual frequency of exceedance of elastic spectral ordinates, a simplified procedure is proposed to estimate mean annual frequencies of exceedance of maximum inelastic displacement demands. Simplifying assumptions are thoroughly examined and discussed. Using readily available elastic seismic hazard curves the procedure can be used to compute maximum inelastic displacement seismic hazard curves and uniform hazard spectra of maximum inelastic displacement demands. The resulting maximum inelastic displacement demand spectra provide a more rational way of establishing seismic demands for new and existing structures when performance‐based approaches are used. The proposed procedure is illustrated for elastoplastic SDOF systems having known‐lateral strength located in a region of high seismicity in California. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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山东地区地震危险性空间分布特征研究 总被引：3，自引：2，他引：1
概述山东省及其周边的地震环境,并以地震危险性概率分析方法研究山东地区峰值地震加速度空间分布特征。分析不同超越概率水准的峰值地震加速度的比值。结果表明,不同超越概率水准的地震危险性分析结果的比例关系对地震环境具有明显的依赖特征,且总体上服从对数正态概率分布。 相似文献
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The balance of a component contained in river water is considered taking into account its input with lateral inflow and decay
in the aquatic environment. Random changes in lateral inflow causes fluctuations in the parameters of component input and
decay. A stochastic equation of component balance is derived and used as the basis for the construction of an equation for
the probability density of component concentration. The solution of this equation shows that the probability density follows
lognormal law. This theoretical result is applicable to the analysis of time series of water salt composition components,
including pH, alkalinity, chlorides, ammonia, iron, and aluminum. The applicability of the lognormal law is proved and distribution
parameters are evaluated. The distributions of three components (pH, alkalinity, and chlorides) are found to split into two
lognormal branches, describing high and low component concentrations. In the case of pH and alkalinity, this splitting is
due to seasonal effects, while in the case of chlorides, it is caused by the difference between concentrations in the surface
runoff at the early and final stages of snow melting and rainfalls. The application of the statistical distributions for probabilistic
forecasting of extreme component concentrations is considered. The exceedance probability of standard limits of the components
is considered. The use of exceedance probability in hydrochemical standardization is demonstrated. 相似文献
16.
基于单一指标的传统地震易损性分析忽略了非结构构件损伤对建筑抗震性能的影响。首先基于多维性能极限状态理论建立了三维性能极限状态方程,并对几种特殊情况下的三维阈值曲面进行了讨论。进而以最大层间位移角作为整体结构与位移敏感型非结构构件的性能指标,以峰值楼面加速度作为加速度敏感型非结构构件的性能指标,对建筑的结构损伤和非结构损伤进行描述。考虑各性能指标之间的相关性和各性能指标所对应的极限状态阈值的不确定性,建立了建筑在地震作用下的三维性能极限状态的超越概率函数。最后,采用Open Sees有限元软件对一7层钢筋混凝土框架填充墙建筑进行增量动力分析,得到其各性能水平下的地震易损性曲线。分析结果表明,当忽略非结构构件损伤时,各性能极限状态的超越概率均降低,从而高估了建筑剩余功能水平,进而导致低估建筑的损失。在考虑各性能指标的极限状态阈值的不确定性时,对任一性能极限状态,不同变异系数取值下的易损性曲线会出现交点,在交点之前超越概率随着变异系数的增大而增大,交点之后则随着变异系数的增大而减小。在考虑性能指标间的相关性时,对任一性能极限状态,超越概率随着相关系数的减小而增大。另外,性能指标阈值的不确定性与性能指标间的相关性对地震易损性的影响随着性能水平的提高而逐渐降低,且对低性能水平下建筑地震易损性有明显影响。 相似文献
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A novel generalized probabilistic formulation is proposed to assess seismicity using earthquake catalogues with uncertain and incomplete data. The seismicity, described by the complete exceedance rate of magnitudes, is estimated starting from a consistent incomplete exceedance rate which is rationally linked to the catalogue data. Complete and incomplete exceedance rates are represented by similar functional forms and they are related by a completeness function, which expresses the probability that an event is included in a data set. Completeness is considered uncertain and it is defined by a suitable, continuous, analytical, magnitude dependent function. The importance of this work lies on its applicability because it can be useful in seismic zones where information about seismic activity is scarce or simply when the catalogue is incomplete in a range of magnitudes that can have a significant influence on the seismic hazard analysis and on the resulting seismic risk assessment. Moreover, it can also be applied in the common case when the catalogue is considered complete above a given magnitude threshold. Numerical examples are presented to illustrate the influence of catalogue incompleteness on the complete exceedance rate estimations. In companion papers, attention is focused on the estimation of completeness probabilities of available catalogues and on parameter estimation of the exceedance rate functions. 相似文献
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依据地震危险性分析的思路，提出一种场地震害预测的方法。依此方法，给出山东地区５０ａ超越概率为１０％的震害预测略图 相似文献
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Optimization and uncertainty analysis of operational policies for multipurpose reservoir system 总被引：1，自引：1，他引：0
Bhola N. S. Ghimire M. Janga Reddy 《Stochastic Environmental Research and Risk Assessment (SERRA)》2014,28(7):1815-1833
This paper presents optimization and uncertainty analysis of operation policies for Hirakud reservoir system in Orissa state, India. The Hirakud reservoir project serves multiple purposes such as flood control, irrigation and power generation in that order of priority. A 10-daily reservoir operation model is formulated to maximize annual hydropower production subjected to satisfying flood control restrictions, irrigation requirements, and various other physical and technical constraints. The reservoir operational model is solved by using elitist-mutated particle swarm optimization (EMPSO) method, and the uncertainty in release decisions and end-storages are analyzed. On comparing the annual hydropower production obtained by EMPSO method with historical annual hydropower, it is found that there is a greater chance of improving the system performance by optimally operating the reservoir system. The analysis also reveals that the inflow into reservoir is highly uncertain variable, which significantly influences the operational decisions for reservoir system. Hence, in order to account uncertainty in inflow, the reservoir operation model is solved for different exceedance probabilities of inflows. The uncertainty in inflows is represented through probability distributions such as normal, lognormal, exponential and generalized extreme value distributions; and the best fit model is selected to obtain inflows for different exceedance probabilities. Then the reservoir operation model is solved using EMPSO method to arrive at suitable operational policies corresponding to various inflow scenarios. The results show that the amount of annual hydropower generated decreases as the value of inflow exceedance probability increases. The obtained operational polices provides confidence in release decisions, therefore these could be useful for reservoir operation. 相似文献
20.
Ground motion evaluation procedures for performance-based design 总被引：1，自引：0，他引：1
Jonathan P. Stewart Shyh-Jeng Chiou Jonathan D. Bray Robert W. Graves Paul G. Somerville Norman A. Abrahamson 《Soil Dynamics and Earthquake Engineering》2002,22(9-12):765-772
The objective of performance-based earthquake engineering (PBEE) is the analysis of performance objectives with a specified annual probability of exceedance. Increasingly undesirable performance is caused by increasing levels of strong ground motion having decreasing annual probabilities of exceedance. Accordingly, the evaluation of ground motion intensity measures is a vital component of PBEE. This paper provides a brief synthesis of ground motion analysis procedures within a performance-based design framework, and is a summary of a recent report to which the reader is referred for details. The principal topics addressed are probabilistic characterizations of source, path, and site effects, with the discussion of these effects focusing principally on applications in active regions such as California. 相似文献