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1.
本文用确定性和随机概率的方法研究了Ｗｕ工桥墩台和小跨拱拱桥在恒载及活载（包括地震效应）作用下决定某截面上的偏心距，以便使其在设计规范规定的限度时所能通过的活载最大等级是什么，由于地震随机性强裂，故基于概率理论的结构可靠性方法优于确定性的方法，但在本文中的结果显示，这两种方法的最终结果十分接近。 相似文献
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本文讨论了巴基斯坦的地震构造，潜在震源和历史与现代地震，并在此基础上使用确定性和概率性两种方法计算了各发展断层５０年内最大可能的地震在卡拉奇和海得拉巴两城市将引起的地面峰值加速度以及５０年内超越概率为１４％的等加速度区划图。 相似文献
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巴基斯坦卡拉奇─海得拉巴区域地震危险性预测 总被引：1，自引：0，他引：1
Shahid A. Khan 《地震研究》1995,(3)
本文讨论了巴基斯坦的地震构造，潜在震源和历史与现代地震活动性，并在此基础上使用确定性和概率性两种方法计算了各发震断层５０年内最大可能的地震在卡拉奇和海得拉巴两城市将引起的地面峰值加速度以及５０年内超越概率为１４％的等加速度区划图。 相似文献
4.
地震危险性分析中的不确定性处理和表征,一直是核电厂厂址地震安全性评价中倍受关注的重要问题,尤其是日本福岛核事故后,无论是确定核电厂厂址的设计基准地震动,还是进行核电厂地震风险评价,都更加重视地震危险性分析中的不确定性.本文通过理论分析重点说明了衰减关系的不确定性,包括标准差和截断水平对核电厂地震安全性评价的影响,并在此基础上,通过算例和讨论说明了概率性方法截断水平的选取问题,探讨了现行确定性方法和概率性方法在截断水平选取上的差异.分析计算结果表明,在地震活动较弱的区域,概率性方法截断水平为3,确定性方法截断水平为0的现行做法是恰当的.但是,对于发震构造大震复发间隔较小的区域,为了使二者在超越概率方面协调,恰当提高确定性方法的截断水平更为合理. 相似文献
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设定地震及其烈度影响判别 总被引：1，自引：0，他引：1
设定地震常用于震害预测、地震小区划和重大工程选址,烈度衰减模型反映了地震引起的地面震动及其影响的强弱程度分布。设定地震包括确定性和非确定性设定两种方法,确定性方法基于构造或历史地震,非确定性方法是基于概率危险性方法,用于估计区域或城市未来可能遭遇的地震危险。缺失等震线或震害记载不详的历史地震和概率设定地震都不能确切地反映地震破坏影响,借助于烈度衰减关系模型和GIS,可直观地判别其影响分布情况,便于设定地震的取舍。 相似文献
7.
地震危险性分析方法的回顾 总被引：1，自引：0，他引：1
地震危险性分析方法的回顾［伊朗］米尔扎依引言地震危险性分析可以分成经验的－统计的、确定性的和概率的等几类方法。经验的方法直接根据历史地震资料和古地震资料来确定地震活动性和评定场点的地震危险性；在确定性分析方法里，表示第四纪或近代地壳活动证据的断层或者... 相似文献
8.
华北北部地区年前地震危险性预测研究组 《地震》1995,(4):391-395
综述了利用确定性和概率性相结合的预测方法，对华北北部地区２００５年前的地震危险性进行了概率预测研究。研究表明，该区在２００年前发生６级以上地震的概率为０．４５，其中涿鹿－怀来一带地区内每个计算单元中的发展概率最高，达到０．０２。 相似文献
9.
讨论了地震造成人员伤亡的相关因素，分析了地震强度、建筑物抗震性能、人口密度、发震时间、地震引起发生灾害及地震预报与地震人员伤亡的相关性。按照确定性方法和概率性方法阐述了国内外地震人员伤亡预测方法，分析了它们的适用条件。并用确定性方法中的建筑物破坏程度与人员伤亡关系法对鲁南地区进行了地震人员伤亡预测。 相似文献
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围绕对地震活动时间和空间不确定性的不同认识和处理方法,分析了地震区划中现有的确定性方法和概率分析方法的不足.分析、总结了地震之间相互关系随时间、空间和震级的变化特征,认为时间和空间不确定性是相互联系、相互制约的,并用最多地震数来反映这种变化特征,进而推导出二项式模型.二项式模型能够反映不同程度的时间和空间不确定性认识.分析了二项式模型与确定性方法和概率分析方法中泊松模型的异、同之处,指出确定性方法和泊松模型分别是二项式模型的两个极限,在时间和空间不确定程度极小和很大两种情况下,二项式模型分别趋近于确定性方法和泊松模型.给出了一种估算隐含概率的方法,具体分析了1977年全国烈度区划图中华北地区5个高烈度区隐含概率的上限值. 相似文献
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A modal-based analysis of the dynamic response variability of multiple degree-of-freedom linear structures with uncertain parameters subjected to either deterministic or stochastic excitations is considered. A probabilistic methodology is presented in which random variables with specified probability distributions are used to quantify the parameter uncertainties. The uncertainty in the response due to uncertainties in the structural modelling and loading is quantified by various probabilistic measures such as mean, variance and coefficient of excess. The computation of these probabilistic measures is addressed. A series expansion involving orthogonal polynomials in terms of the system parameters is first used to model the response variability of each contributing mode. Linear equations for the coefficients of each series expansion are derived using the weighted residual method. Mode superposition is then used to derive analytical expressions for the variability and statistics of the uncertain response in terms of the coefficients of the series expansions for all contributing modes. A primary–secondary system and a ten-story building subjected to deterministic and stochastic loads are used to demonstrate the methodology, as well as evaluate its performance by comparing it to existing methods, including the computationally cost-efficient perturbation method. 相似文献
12.
Deterministic and probabilistic floor response spectra 总被引：1，自引：0，他引：1
The paper presents a comparative study for computing floor response spectra (FRS) for complex structures. For the purpose of validation and evaluation of the methods for practical application, a systematic comparison of two concepts, classical deterministic and probabilistic, was carried out as an example of a nuclear power plants structure. The deterministic method utilizes time history analyses compatible with the prescribed design response spectrum. The probabilistic method uses an analysis of random vibrations for defining the probabilistic FRS influenced by random seismic soil movement. The seismic input is a power spectral density function (PSDF) compatible with the design response spectrum. The probabilistic approach based on PSDF provides satisfying FRS with far less effort and time consumption needed for calculation. 相似文献
13.
Probabilistic SWE reanalysis as a generalization of deterministic SWE reconstruction techniques 
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下载免费PDF全文 Snow accumulation and melt is highly variable in space and time in complex mountainous environments. Therefore, it is necessary to provide high‐resolution spatially and temporally distributed estimates of sub‐basin snow water equivalent (SWE) to accurately predict the timing and magnitude of snowmelt runoff. In this study, we compare two reconstruction techniques (a commonly used deterministic reconstruction vs a probabilistic data assimilation framework). The methods retrospectively estimate SWE from a time series of remotely sensed maps of fractional snow‐covered area (FSCA). In testing both methods over the Tokopah watershed in the Sierra Nevada (California), the probabilistic reconstruction approach is shown to be a more robust generalization of the deterministic reconstruction. Under idealized conditions, both probabilistic and deterministic approaches perform reasonably well and yield similar results when compared with in situ verification data, whereas the probabilistic reconstruction was found to be in slightly better agreement with snow‐pit observations. More importantly, the probabilistic approach was found to be more robust: unaccounted for biases in solar radiation impacted the probabilistic SWE estimates less than the deterministic case (4% vs 7% errors for water year (WY)1997 and 0% vs 3% errors for WY1999); the probabilistic reconstruction was found to be less sensitive to the number of available observations (6% vs 10% errors in WY1997 and 13% vs 44% errors in WY1999 from the nominal cases when four fewer FSCA images were available). Finally, results from the probabilistic reconstruction approach, which requires precipitation inputs (unlike the deterministic approach), were found to be relatively robust to bias in prior precipitation estimates, where the nominal case mean estimates were recovered even when an underestimated prior precipitation was used. The additional robustness of the probabilistic SWE reconstruction technique should prove useful in future applications over larger basins and longer periods in mountainous terrain. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
14.
A. Chaudhuri M. Sekhar 《Stochastic Environmental Research and Risk Assessment (SERRA)》2006,21(2):159-173
During probabilistic analysis of flow and transport in porous media, the uncertainty due to spatial heterogeneity of governing parameters are often taken into account. The randomness in the source conditions also play a major role on the stochastic behavior in distribution of the dependent variable. The present paper is focused on studying the effect of both uncertainty in the governing system parameters as well as the input source conditions. Under such circumstances, a method is proposed which combines with stochastic finite element method (SFEM) and is illustrated for probabilistic analysis of concentration distribution in a 3-D heterogeneous porous media under the influence of random source condition. In the first step SFEM used for probabilistic solution due to spatial heterogeneity of governing parameters for a unit source pulse. Further, the results from the unit source pulse case have been used for the analysis of multiple pulse case using the numerical convolution when the source condition is a random process. The source condition is modeled as a discrete release of random amount of masses at fixed intervals of time. The mean and standard deviation of concentration is compared for the deterministic and the stochastic system scenarios as well as for different values of system parameters. The effect of uncertainty of source condition is also demonstrated in terms of mean and standard deviation of concentration at various locations in the domain. 相似文献
15.
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《Journal of Hydrology》2006,316(1-4):28-42
This paper presents a synthesis of a probability-based approach and the underpinning, mathematical and philosophical foundations that have evolved to date, as well as applications in modeling of vertical and two-dimensional velocity distributions that have direct implications to measurements and estimation of transport of mass, momentum and energy in fluid flows. The approach draws inferences from a probability law identified by maximizing the information entropy under the constraints imposed by the available information. It gives predictions considered to be the most probable or objective on the basis of the available information. The probabilistic approach complements the deterministic approach of hydrodynamics. The difference in the point of view between the two approaches creates a different view about the available information. Some information, such as the location and magnitude of maximum velocity, the ratio of mean and maximum velocities, that may not appear to have direct use to the deterministic approach in flow predictions become important and useful to the probabilistic approach. 相似文献
17.
总结了地震安全性估计方法的现状与发展趋势,指出我国在用确定性方法确定设计地震动时,有些不确定性并未考虑,不少主观决定并非总是足够安全的。文中推荐了概率方法。场地影响分析中,特别是座落于软基上的核设施,需要对输入面的选择及土层反应分析中的多种不确定因素进行考虑。最后指出场地地震相关反应谱对座落于软基上的核设施的重要意义,以及大远震与小近震对反应谱的不同影响 相似文献
18.
In the linear seismic design of buildings, the (deterministic) substructure method is a customary and efficient approach. However, the existence of spatial variability in the parameters of the mechanical model of the soil, as well as parametric errors, calls for the use of probabilistic approaches in order to provide a reliable design of the structure. The construction of probabilistic models of the soil impedance matrix provides a natural path to such approaches within the context of the substructure method. Two main techniques are described in this paper: a parametric one, typically using the stochastic finite element method, and a nonparametric one, which was introduced more recently. The latter is explored more specifically, and the possibilities it offers in terms of seismic design are presented. In particular, it is shown that it allows for the estimation of quantiles of the quantities of interest, rather than confidence intervals, which lead to highly conservative design. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
19.
Assessing the impact of land use change on hydrology by ensemble modeling (LUCHEM) III: Scenario analysis 总被引：1，自引：0，他引：1
J.A. Huisman L. Breuer H. Bormann A. Bronstert B.F.W. Croke H.-G. Frede T. Gräff L. Hubrechts A.J. Jakeman G. Kite J. Lanini G. Leavesley D.P. Lettenmaier G. Lindström J. Seibert M. Sivapalan N.R. Viney P. Willems 《Advances in water resources》2009
An ensemble of 10 hydrological models was applied to the same set of land use change scenarios. There was general agreement about the direction of changes in the mean annual discharge and 90% discharge percentile predicted by the ensemble members, although a considerable range in the magnitude of predictions for the scenarios and catchments under consideration was obvious. Differences in the magnitude of the increase were attributed to the different mean annual actual evapotranspiration rates for each land use type. The ensemble of model runs was further analyzed with deterministic and probabilistic ensemble methods. The deterministic ensemble method based on a trimmed mean resulted in a single somewhat more reliable scenario prediction. The probabilistic reliability ensemble averaging (REA) method allowed a quantification of the model structure uncertainty in the scenario predictions. It was concluded that the use of a model ensemble has greatly increased our confidence in the reliability of the model predictions. 相似文献