Software for progressive failure analysis of transmission line structures under the action of downbursts and tornadoes

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Downbursts and tornadoes belong to a category of localized windstorms that are called High Intensity Wind (HIW) events. Among structures that have suffered significant damage due to HIW events in the past are transmission lines. Because of their extended length, the probability of a tornado or a downburst hitting one of the towers, which supports such lines, is very high. Moreover, the failure of one tower can trigger the collapse of many towers in a domino effect. Researchers at Western University are taking the lead worldwide in the area of HIW events in general and the impact of such events on transmission line structures in particular. The research at Western started about 15 years ago through collaboration with Manitoba Hydro after the failure of 19 towers due to a downburst that occurred in 1999 near Winnipeg. Triggered by the failure of many Ontario towers, Hydro One Ontario subsequently funded the first phase of a related research program; this funding was leveraged by NSERC and the Ontario Center of Excellence. This research led to the only software available in the world that can predict the forces acting on a transmission tower and the response of such a tower to an HIW event. The first experiment in the world involving the testing of a multi-span transmission line system under downbursts was also carried-out in the project at the unique WindEEE facility. In the current study, the research will be taken to a higher level by considering the behaviour of entire line rather than that of an individual tower. The software will be further developed so that it will have the capacity to predict the progression of failure from one tower to another during an HIW event. This numerical development will be validated using a novel test to be conducted at WindEEE. The output of this research will provide Hydro One with unique tools that will allow that company to make the most optimum engineering decisions in either upgrading an existing line or in designing a new line in order to minimize the devastating losses associated with HIW events. Other North American utility companies will benefit as well. In fact, the impact will be global as the applicant serves on numerous international committees related to this subject.