Specification of the design snow loads for gable roofs based on a consistent probabilistic approach

基于一致概率方法的山墙屋顶设计雪荷载规范

• 批准号: 99264718
• 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: 2009
• 资助国家: 德国
• 起止时间: 2008-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/99264718?language=en
• 关键词: Specification; design; snow; loads; gable

One of the basic tasks of codification in regard to climatologic actions is the area-wide specification of the design values based on observations for single stations. The statistical stability of the estimated values greatly depends on the ensemble size. This is true for the estimates of each single station as well as for the geostatistical interpolation, i.e. the more observations are sampled for the single station ensembles and the more stations are used as input for the geostatistical interpolaten the higher is the statistical stability of the results. For 224 stations in Germany, extreme value statistics can be performed directly based on the observed water equivalents, which are available on average for 37 years. The developed probabilistically equivalent snow density model in combination with the new approach of using independent events instead of yearly extremes leads to considerable larger ensemble sizes with 130 entries on average. The translation of the single station model to regional models allows analysing a further 525 stations which provide only observations of the height of the snow cover. A further improvement, i.e. a reduction of the statistical uncertainties, is obtained by introducing super-stations which combine observations from single stations following a consistent probabilistic strategy. Then, the type of distribution can be identified with a sufficient statistical stability. Aim of the project is the utilization of the observed snow height data in the scope of the extreme value statistics of the snow loads and the statistical optimal specification of the corresponding design values. This requires a consistent strategy for the detection of outliers in terms of very rare events. The actual strategy used in the European snow load research is less appropriate, since too many events are not detected and a large number of events are erroneously classified as outlier. Aim of the project is the development and application of an improved strategy, which especially considers unbiased estimators like BLUE. Thus, it becomes possible to analyse true outliers in a probabilistic consistent way. The accumulation and spatial distribution of snow on roofs greatly depends on the wind speed. The snow-wind climate of Germany can be sub-divided into three basic types. Type I shows for large snow loads virtually deterministic wind speed values. Then, the shape parameters can be specified on the load model which has been developed in the first period of the project. Type II features scattering wind speeds, which requires extensions of the basic convolution integrals. Only for type III storm and snow occur simultaneously. Then, consistent combination rules are required for these two climatologic actions.

关于气候作用的编纂工作的基本任务之一是根据单站的观测结果在整个区域范围内确定设计值。估计值的统计稳定性很大程度上取决于系综的大小。这对于每个单站的估计值以及地质统计插值都是如此，即对单站集合的观测值采样越多，并且用作地质统计插值输入的站越多，结果的统计稳定性就越高。对于德国的224个站点，可以直接根据观测的水当量进行极值统计，平均37年可获得。开发的概率等效的雪密度模型结合使用独立的事件，而不是每年的极端的新方法，导致相当大的合奏大小与平均130个条目。将单站模型转换为区域模型可以分析另外525个站，这些站只提供积雪高度的观测。进一步的改进，即统计不确定性的减少，是通过引入超级站，联合收割机从单个站的观察后，一致的概率策略。然后，分布的类型可以识别具有足够的统计稳定性。该项目的目的是利用观测到的雪高数据的范围内的极值统计雪荷载和相应的设计值的统计优化规范。这就需要一个一致的策略来检测非常罕见的事件中的离群值。在欧洲雪荷载研究中使用的实际策略是不太合适的，因为太多的事件没有被检测到，大量的事件被错误地归类为离群值。该项目的目的是开发和应用一种改进的策略，特别考虑像BLUE这样的无偏估计。因此，可以以概率一致的方式分析真正的离群值。屋顶积雪的积累和空间分布在很大程度上取决于风速。德国的风雪气候可分为三种基本类型。类型I显示了大雪荷载下实际上确定的风速值。然后，可以在项目第一阶段开发的负载模型上指定形状参数。第二类的特点散射风速，这需要扩展的基本卷积积分。仅适用于第三类风暴和降雪同时发生。因此，这两种气候作用需要一致的组合规则。