re:building bridges

FRP bridge of the future
Fiber-reinforced polymer decks offer durability and easy installation and may become key to the development of very long bridges, where being lightweight is a critical feature. Illustration by Jeff Harper.

Last summer’s collapse of the Interstate 35W bridge in Minneapolis served as a stark reminder that the nation’s infrastructure is aging, and was a dramatic example of the type of disaster researchers at Missouri S&T are working to prevent.

Long before the collapse occurred, Missouri S&T researchers were busy developing new materials and testing methods to preserve and protect the nation’s roads, bridges and buildings.
As one of only 10 national university transportation centers in the United States, Missouri S&T’s Center for Transportation and Infrastructure Safety is bringing together researchers from a variety of disciplines to address some of the nation’s most pressing transportation issues.
As a result of their research, we may one day find ourselves driving across bridges made from soybeans and reinforced with glass, carbon or steel fibers. While we travel across these cutting-edge structures, sensors will monitor the impact of our vehicles and warn technicians at the first signs of trouble.
Nearly 30 percent of the country’s bridges are structurally deficient or functionally obsolete, according to a 2006 report from the U.S. Department of Transportation. Developments at Missouri S&T in alternative building materials and methods of monitoring the structural “health” of roads and bridges could be the keys to safer and stronger transportation systems. In addition, faculty members are training today’s students for a world in which these new approaches to bridge- and road-building will become commonplace.
“We want to educate the next generation of transportation engineers,” says John Myers, associate professor of civil, architectural and environmental engineering and director of Missouri S&T’s transportation center.
Myers and his colleagues are creating and testing alternatives to traditional building materials like steel and concrete. Polymers reinforced with carbon, glass and steel fibers already have been tested on 26 bridges in Missouri and surrounding states. A polymer made from soybeans is even being developed, and K. Chandrashekhara, Curators’ Professor of mechanical and aerospace engineering and director of Missouri S&T’s Composite Manufacturing Laboratory, said the material could be used to build bridge decks that are strong, corrosive-resistant and environmentally friendly.
Many of the bridges where new materials are tested are also being monitored by devices invented by Missouri S&T faculty. One such device is a sensor developed by Genda Chen, professor of civil, architectural and environmental engineering. The sensor can provide a three-dimensional model of cracks in a structure, as well as information about where and when the crack occurred.
Another device developed at Missouri S&T, called a Flood Frog, is being used to test bridges for health indicators such as strain, humidity, water level and vibration. The “frog” is an inexpensive, battery-powered device inside a waterproof case. It can easily be fixed to the outside of a structure.
“The Flood Frog can measure pretty much any quantity,” says its developer Sahra Sedigh, assistant professor of electrical and computer engineering. By exposing a bridge’s weaknesses in their early stages, “it opens a lot more doors to securing bridges than any other technology around.”
Although it might seem like something straight out of science fiction, Missouri S&T researchers have even invented an inspection method that uses microwaves to see through sheets of reinforced polymer.
When researchers aren’t working in the field, they can still conduct large-scale tests at Missouri S&T’s high-bay lab, where it’s possible to simulate the stress an earthquake puts on a bridge. Much of the testing is part of a larger project for the Network of Earthquake and Engineering Simulation.
“We are unique because we are one of only about 10 schools in the nation that can take the entire body of a bridge and test it,” says Abdeldjelil Belarbi, Curators’ Teaching Professor of civil, architectural and environmental engineering. “We are trying to duplicate exactly what happens to a bridge in the real world.”
Belarbi and his colleagues hope their work will lead to the development of a new design code for transportation infrastructure that will aid engineers in building bridges with life spans of up to 100 years.

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