POWER-GRID RESILIENCETowers in the Storm

Published 5 January 2023

The problem with the U.S. electrical grid is that many transmission towers have exceeded their design life by about 50 years, which means the aging grid today faces bigger chances of failure. One threat to the grid is from damaging winds of extreme storms such as hurricanes.

Most people in the U.S. don’t give a second thought to flipping a switch for light. The U.S. made big investments in the mid-20th-century on the transmission side of the national electric grid to provide reliable electricity to society. The problem is that many transmission towers have exceeded their design life by about 50 years, which means the aging grid today faces bigger chances of failure.

One threat to the grid is from damaging winds of extreme storms such as hurricanes. Case in point — over $25 billion dollars in wind damage from Hurricane Michael, which in 2018 toppled about 100 transmission towers in Florida.

A new set of laboratory experimental data aims to help scientists and engineers understand and avert the threat of gale-force winds on electric transmission structures. The project  (PRJ-1379) won a 2022 DesignSafe Dataset Award , which recognized the dataset’s diverse contributions to natural hazards research.

The researchers used one of the world’s most powerful hurricane simulators, the Natural Hazards Engineering Research Infrastructure (NHERIWall of Wind Experimental Facility at Florida International University (FIU) and funded by the National Science Foundation (NSF). Realistic 1:50 scale models of transmission towers and a multi-span transmission electrical cable system were worked over by the Wall of Wind, capable of generating Category 5 hurricane-force winds of 157 miles per hour.

Different wind speeds and directions were tested to simulate the chaos and complexity of real hurricanes. The tests, conducted in July 2019, measured the elastic forces induced by motions of the structure, the wind and different components of this structure under wind-structure interaction effects.

The science team published parts of their results in July 2021 in the journal Engineering Structures. Several other papers based on the generated data from this project are currently under review.

“One of the main outcomes so far, and the reason it’s still ongoing after the project has ended, is the identification and characterization of the most important parameters for analysis and design of these structures,” said Abdollah Shafieezadeh, Lichtenstein Associate Professor in the Department of Civil, Environmental and Geodetic Engineering at The Ohio State University (OSU).