Specification of the design wind load based on wind tunnel experiments considering the statistical uncertainties due to limited ensemble sizes

考虑到有限集合尺寸导致的统计不确定性，基于风洞实验的设计风荷载规范

基本信息

批准号：
282761584
负责人：
Privatdozent Dr.-Ing. Michael Kasperski
金额：
--
依托单位：
Forschungsteam EKIB - Entwurfsgrundlagen im Konstruktiven Ingenieurbau
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2015
资助国家：
德国
起止时间：
2014-12-31 至 2021-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/282761584?language=en
关键词：
Specification design wind load based

项目摘要

For the specification of the design wind load based on wind tunnel experiments statistical uncertainties have to be considered which are obtained from confined ensembles. The basic strategy for meeting a chosen confidence interval uses an adjusting factor which especially depends on the ensemble size. A corresponding procedure is implemented e.g. in the Eurocode DIN-EN 1990:2010-12 in the annex Design by testing for the specification of the design value of the resistance. The project aims in developing the adjusting factors for an optimal method for the estimation of the design value of the aerodynamic coefficient. While these adjusting factors guarantee that the ratio of unsafe solutions remains constant independent of the ensemble size, the ratio of uneconomic solutions in terms of considerable overestimated design wind loads increases for decreasing ensemble size. Fundamentally new, this ratio is developed to obtain an aid to decision-making in regard to the required number of wind tunnel runs following the basic principle as few runs as possible and as many runs as necessary. Opposite to the resistance side, there is no uniform target fractile value for the design value of the aerodynamic coefficients; the target value rather depends on the variation coefficient of the extremes. Consequently, adjusting factors are required depending on the ensemble size and the variation coefficient. Two alternative approaches are available for the estimation of the design value. The first approach directly uses independent extremes, either picked from single runs or from subsets. The basic advantage of using subsets lies in an enlarged ensemble size, basically leading to an increased statistical stability. However, for subsets the target fractile value increases, leading to decreasing statistical stability. Furthermore, for subsets becoming shorter and shorter there is the basic danger that the subset is no longer representative. Fundamentally new, an enlarged ensemble size is obtained by peaks-over-threshold sampling. Estimations especially are performed based on the Best Linear Unbiased Estimator (BLUE). The second approach estimates the design values based on an equivalent normal distribution using the Rice method. The fundamental elements of this approach are the estimation of the translation rule using CDF-mapping or Hermite polynomials, and the estimation of the cycling rate either using the variance of the time derivative or the frequency-weighted integration of the estimated spectral density function. The optimal method is obtained by comparing quality features of the estimations obtained by the different methods, especially the ratio of considerable uneconomic estimations.

对于基于风洞实验的设计风荷载规范，必须考虑从受限系综中获得的统计不确定性。满足所选置信区间的基本策略使用调整因子，该因子尤其取决于整体大小。实施相应的程序，例如在欧洲规范 DIN-EN 1990:2010-12 的附件中，通过测试来确定电阻设计值的规范。该项目旨在开发用于估计空气动力系数设计值的最佳方法的调整因素。虽然这些调整因素保证了不安全解决方案的比例保持恒定，与整体尺寸无关，但随着整体尺寸的减小，在相当高估的设计风荷载方面，不经济解决方案的比例会增加。该比率是全新的，旨在为有关所需风洞运行次数的决策提供帮助，遵循尽可能少的运行和尽可能多的运行的基本原则。与阻力侧相反，气动系数的设计值没有统一的目标分位值；目标值更取决于极值的变异系数。因此，需要根据集合大小和变异系数调整因子。有两种替代方法可用于估计设计值。第一种方法直接使用独立的极值，从单次运行或子集中选取。使用子集的基本优点在于扩大了整体规模，基本上提高了统计稳定性。然而，对于子集，目标分位数值增加，导致统计稳定性降低。此外，对于变得越来越短的子集，存在子集不再具有代表性的基本危险。全新的是，通过峰值阈值采样获得了扩大的集合大小。估计尤其是基于最佳线性无偏估计器（BLUE）来执行。第二种方法使用 Rice 方法根据等效正态分布估计设计值。该方法的基本要素是使用 CDF 映射或 Hermite 多项式来估计平移规则，以及使用时间导数的方差或估计的谱密度函数的频率加权积分来估计循环速率。通过比较不同方法获得的估计的质量特征，特别是相当大的不经济估计的比例，得出最优方法。