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.

为了规范设计风荷载，必须考虑基于风洞实验的统计不确定性，这些统计不确定性必须从密封的集合中获得。满足所选置信区间的基本策略使用调整因子，尤其取决于整体尺寸。实施相应的过程，例如在Eurocode Din-en 1990：2010-12中，在附件设计中测试了电阻的设计值的规格。该项目旨在开发一种调整因子，以估计空气动力系数的设计值的最佳方法。尽管这些调整因子确保不安全溶液的比率保持恒定与整体大小无关，但根据大量高估的设计风负载增加了不经济解决方案的比率，以减小整体尺寸。从根本上开始，该比率是为了获得有关遵循基本原则所需数量的最少跑步和尽可能多的运行的风洞数量的决策的援助。与电阻侧相反，空气动力系数的设计值没有均匀的目标分裂值。目标值取决于极端的变化系数。因此，根据整体尺寸和变化系数，需要调整因子。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端，要么是从单次运行或从子集中挑选的。使用子集的基本优势在于整体的扩大，基本上导致统计稳定性提高。但是，对于子集，目标分裂值增加，导致统计稳定性下降。此外，对于子集变得越来越短，基本危险是该子集不再是代表性的。从根本上讲，新的合奏大小是通过阈值峰值采样获得的。尤其是根据最佳线性无偏估计器（蓝色）进行估计。第二种方法使用水稻方法基于等效的正态分布估算了设计值。这种方法的基本要素是使用CDF映射或HERMITE多项式对翻译规则的估计，以及使用时间导数的方差或估计光谱密度函数的频率加权整合进行循环速率的估计。最佳方法是通过比较通过不同方法获得的估计的质量特征获得的，尤其是相当不经济估计的比率。