Behaviour and design procedures for transmission towers under high intensity wind loads

包括龙卷风和暴雨在内的高强度风（HIW）是造成全球80%以上与天气有关的输电线路故障的原因。尽管如此，输电线路的设计规范是基于与大型事件相关的传统风廓线。HIW有不同的轮廓，这影响了风荷载在塔和线路上的分布。UWO与马尼托巴水电（MH）和其他公用事业公司合作开展了一项研究计划。开发了一种预测输电线路对高温高压响应的数值工具。它结合了从计算流体动力学分析中获得的模拟HIW的风场。该数值模型的各个组成部分分别进行了验证。研究表明，位于塔楼不同区域的结构构件可能具有特定的临界HIW特征，这些特征由事件的大小和位置定义，从而导致这些构件中的最大力。在目前的研究中，将对输电线路系统的风速和振动进行连续监测。研究结果将提供更多关于高强度辐射场和塔对这些事件的反应的见解。它们还将用于验证整个数值模型。许多具有不同结构配置的输电线路系统将进行数值模拟。研究结果将用于提出一组设计荷载案例，模拟各种结构系统的关键HIW案例的包络。数值模型将纳入输电线路各部件的精确失效模型。这将有助于研究高塔在高温下的逐渐倒塌。这个扩展的模型，连同现有的HIW气候数据，将导致设计程序的发展，其中将包括推荐的风速和设计负载情况。设计程序将确保输电线路在中度高温下不受损，同时防止在强高温下完全坍塌。这将有助于减轻高温天气期间输电线路故障造成的经济和社会损失。本提案将涉及三名博士和两名硕士学生。

High Intensity Winds (HIW), which include tornadoes and downbursts, are responsible for more than 80% of all the world's weather-related transmission line failures. Despite this fact, the codes of design for transmission lines are based on a conventional wind profile associated with large scale events. HIW have different profiles, which impact the distribution of wind loads over the towers and lines. A research program was conducted at UWO in collaboration with Manitoba Hydro (MH) and other utility companies. A numerical tool was developed to predict the response of transmission lines to HIW. It incorporates wind field simulating HIW obtained from a computational fluid dynamic analysis. Various components of this numerical model were validated separately. The study revealed that structure members located at various regions of a tower can have specific critical HIW characteristics, defined by the size and location of the event, that lead to maximum forces in these members. In the current study, continuous monitoring for the wind velocity and the vibrations of a transmission line system will be conducted. The results will provide more insight about the HIW fields and the response of the towers to those events. They will also be used to validate the entire numerical model. A number of transmission line systems, having various structural configurations, will be numerically modeled. The results will be used to propose a set of design load cases simulating an envelope for the critical HIW cases for various structural systems. An accurate failure model for various components of the transmission lines will be incorporated into the numerical model. This will allow studying the progressive collapse of the towers during HIW. This extended model, together with available climate data for HIW, will lead to the development of a design procedure that will include recommended wind speeds and design load cases. The design procedure will ensure that transmission lines remain undamaged during moderate HIW, while preventing a total collapse during strong HIW. This will help in mitigating the economical and social losses associated with the failures of transmission lines during HIW. Three Ph.D. and two M.Sc. students will be involved in this proposal.