The metal poles that carry power lines across the country, which measure up to 12 feet in diameter and 100 feet in height, are built to take whatever blows at them. But transmission poles still can fail under the stress of extreme ice and wind, and they could be vulnerable to an infrastructure attack. When one falls, others are pulled down until heavy dead-end structures stop the cascading collapse. Jon “Matt” Rouse, assistant professor of civil, construction, and environmental engineering at Iowa State University, and civil engineering graduate student Casey Faber designed a pole that not only resists cascading failures but also is cheaper and easier to use. The hinged poles don’t require a crane for installation, and if they’re exposed to an extreme load they could be repaired rather than replaced. They would resist cascading failures so utilities could eliminate expensive dead-end structures. And they would allow power companies to provide better and more reliable service.
The key to the technology is a new approach to structural design based primarily on deformation ability rather than strength, resulting in a nominally rectangular pole with a built-in hinge near the base. Metal plates on either side of the hinge act as replaceable structural fuses that stretch and buckle when the pole sustains an extreme load, allowing it to deflect while shielding the rest of the pole from damage. Tendon cables run up and down the inside of the pole to resist stretching and keep the pole upright. When a failure occurs, the fuses bend, the hinge pivots, the interior cables tighten, and nearby poles pick up some of the load. The researchers have successfully tested a prototype pole and are working to secure a patent. Utility and power structure industries have expressed interest in their technology, they add.
Source: PhysOrg.com