Resilience of Transmission Line Structures to Extreme Weather Events

所有基础设施运行对电力的依赖使电力成为现代生活的重要组成部分。因此，灾害事件期间的电力中断可能对安全、经济保障和公共卫生产生破坏性影响。拟议的工作将侧重于极端风事件对输电线路（TL）结构的影响，输电线路是最容易受到风危害的电网要素。在加拿大和其他国家，涉及这些结构在极端大风条件下损坏的事件每年都会发生，气候变化的影响正在加剧这种事件发生的频率和强度。申请人的开创性研究导致了世界上第一个规范的创建，该规范能够有效地设计新的TL结构，以抵抗龙卷风和倾盆大雨（雷暴风），该规范被纳入2020年美国土木工程师协会指南。然而，最大的挑战在于评估现有结构的结构性能。拟议的工作将涉及开发和验证一个最先进的数值模型，该模型将包括TL段中塔的同时模拟，同时考虑塔之间通过中间导体发生的相互作用。该模型能够准确预测大风作用下塔架的破坏模式，计算破坏机制对相邻塔架的动力作用，模拟塔架间的倒塌过程，预测层叠倒塌的程度。该模型将结合由计算流体动力学（CFD）模拟确定的天气动态风荷载，再加上下击和龙卷风荷载。该数值模型的所有组成部分将在世界上唯一的三维风室——造价3000万美元的windee穹顶上进行实验验证。这项研究将在各种极端风事件下与TL结构行为相关的知识方面取得突破性进展，并将为公用事业公司特别是整个社会提供非常有益的工具。升级整个TL网络是不可能的。开发的工具将能够最准确地评估单个网络段的故障风险，并根据线路的重要性、冗余水平以及与其他公用设施的连接，促进明智和经济有效的升级决策。由于电力是城市系统的支柱，考虑到基础设施组件之间的依赖关系，拟议的研究代表了实现申请人长期目标的关键里程碑，即创建工具来评估社区对天气相关灾害的恢复能力。这些研究将为8名研究生提供最先进的数值和实验技术培训，同时解决一个严重的实际和紧迫的问题。

The reliance of all infrastructure operation on electrical power has made electricity a vital component of modern life. Power disruptions during a hazard event can thus have devastating effects on safety, economic security, and public health. The proposed work will focus on the impact of extreme wind events on transmission line (TL) structures: the grid elements most vulnerable to wind hazards. In Canada and other countries, incidents involving the failure of those structures during extreme wind conditions are annual events, and the effects of climate change are exacerbating the frequency and intensity of their occurrence. The applicant's pioneer research led to the creation of the world's first specification that enables the effective design of new TL structures to resist tornadoes and downbursts (thunderstorm wind), which was incorporated into the 2020 American Society of Civil Engineers guidelines. However, the greatest challenge lies in assessing the structural behaviour of existing structures. The proposed work will involve developing and validating a state-of-the-art numerical model that will include the simultaneous simulation of the towers in a TL segment while considering the interaction that happens between the towers through the in-between conductors. The model will accurately predict the failure mode of a tower during a wind event, compute the dynamic forces induced on adjacent towers during the failure mechanism, simulate the collapse as it progresses from tower to tower, and forecast the extent of the cascading collapses. The model will incorporate synoptic dynamic wind loads determined from computational fluid dynamics (CFD) simulations of real conditions at the line area plus downburst and tornado loads. All components of this numerical model will be validated experimentally at the $30M WindEEE dome, the world's only three-dimensional wind chamber. This research will provide a breakthrough advance in knowledge related to TL structural behaviour under various types of extreme wind events and will produce highly beneficial tools for utility companies in particular and society in general. Upgrading an entire TL network is impossible. The developed tool will enable the most accurate assessment of the failure risk for individual network segments and will facilitate informed and cost-effective upgrade decisions based on the importance of the line, the level of redundancy, and the connectivity with other utilities. Since electricity forms the backbone of an urban system, the proposed studies represent a key milestone in achieving the applicant's long-term goal of creating tools for evaluating community resilience to weather-related hazards, taking into account the dependencies among infrastructure components. The studies will provide eight graduate students with training in state-of-the-art numerical and experimental techniques, while addressing a serious practical and pressing problem.