结构的大气结冰

[中文适用范围]： 本文件描述了确定本条款所列结构类型上冰载荷的一般原则。 如果某个结构未被本文件或其他标准或建议直接涵盖，设计者可以使用本文件的意图。然而，用户有责任仔细考虑本文件对所讨论结构的适用性。 本文件中所有数据的实际使用基于对结构现场的一定了解。使用有关现场“正常”结冰量（=冰等级）程度的信息。然而，对于许多地区，没有可用的信息。 即使在这样情况下，本文件也可以有用，因为当地气象学家或其他有经验的人应该能够安全地估计一个适当的冰等级。在结构设计中使用这样的估计将比不考虑冰问题设计出更安全的结构。 警告—设计考虑一些冰而不是没有冰是极其重要的，然后冰量是否正确的问题就不那么重要了。特别是，由于暴露面积增加和阻力系数增加，风的动作可以显著增加。 本文件旨在用于确定以下类型结构上的冰质量和风载荷： —桅杆； —塔； —天线和天线结构； —电缆、拉索、绳索等； —索道（缆车铁路）； —滑雪缆车结构； —建筑物或其部分暴露于潜在结冰； —特殊类型结构的塔，如输电线路、风力涡轮机等。 电气架空线上的大气结冰由IEC（国际电工委员会）标准涵盖。 本文件旨在与ISO 2394一起使用。 注：提到了一些典型的结构类型，但设计者也可以通过考虑哪些类型的结构对不可预见的冰敏感来考虑其他类型。 此外，在许多情况下，只有结构的一部分需要设计用于冰载荷，因为它们比整个结构更容易受到不可预见的冰的影响。 即使电气架空线由IEC标准涵盖，设计者也可以根据需要将本文件用于架空线的桅杆结构（这些不在IEC标准范围内）。 [外文原描述]： ISO 12494:2017 describes the general principles of determining ice load on structures of the types listed in this clause. In cases where a certain structure is not directly covered by this or another standard or recommendation, designers can use the intentions of this document. However, it is the user's responsibility to carefully consider the applicability of this document to the structure in question. The practical use of all data in this document is based upon certain knowledge of the site of the structure. Information about the degree of "normal" icing amounts (= ice classes) for the site in question is used. For many areas, however, no information is available. Even in such cases, this document can be useful because local meteorologists or other experienced persons should be able to, on the safe side, estimate a proper ice class. Using such an estimate in the structural design will result in a much safer structure than designing without any considerations for problems due to ice. CAUTION It is extremely important to design for some ice instead of no ice, and then the question of whether the amount of ice was correct is of less importance. In particular, the action of wind can be increased considerably due to both increased exposed area and increased drag coefficient. ISO 12494:2017 is intended for use in determining ice mass and wind load on the iced structure for the following types of structure: - masts; - towers; - antennas and antenna structures; - cables, stays, guy ropes, etc.; - rope ways (cable railways); - structures for ski-lifts; - buildings or parts of them exposed to potential icing; - towers for special types of construction such as transmission lines, wind turbines, etc. Atmospheric icing on electrical overhead lines is covered by IEC (International Electrotechnical Commission) standards. This document is intended to be used in conjunction with ISO 2394. NOTE Some typical types of structure are mentioned, but other types can also be considered by designers by thinking in terms of which type of structure is sensitive to unforeseen ice, and act thereafter. Also, in many cases, only parts of structures are to be designed for ice loads because they are more vulnerable to unforeseen ice than is the whole structure. Even if electrical overhead lines are covered by IEC standards, designers can use this document for the mast structures to overhead lines (which are not covered by IEC standards) if they so wish.