Students and faculty work to ensure bridge safety
Campus group partners with KDOT to extend life of older structures and save money
The group works with engineers to develop new technologies that can prolong the life of bridges and signal when they need repairs.
By Dylan Sands
Friday, September 7th, 2007
A group of students and faculty at the University of Kansas has thousands of pounds of pressure at its command and is using that pressure to help ensure the safety of drivers in Kansas. The team of engineers is working to prolong the lives of steel bridges and is saving taxpayers millions of dollars in the process.
The Fatigue and Fracture Research Group uses computer simulations, field work, lab tests and experimental composite materials to study steel bridges’ strength and susceptibility toward breakage. One machine in the group’s lab is capable of applying thousands of pounds of pressure to steel bridge parts to simulate the repeated passage of large trucks.
Photo by Sarah Leonard
Benjamin Kaan, Wheatridge, Col. graduate student, tests a steel specimen on the hydrolic test frame in Learned Hall. The steel specimens are being tested in a study to retrofit existing bridges to improve fatigue performance. "We're trying to figure out ways to keep cracks from forming," Kaan said.
The American Society of Civil Engineers reports that more than 75,422 bridges throughout the U.S. are structurally deficient. It estimates that more than $180 billion will need to be spent during the next 20 years to fix the bridges.
“‘Structurally deficient’ does not mean the bridge is going to fall down tomorrow,” said Caroline Bennett, assistant professor of engineering and member of the bridge team. “It only means that Congress needs to put more money into bridge research.”
The group works with the Kansas Department of Transportation to extend the life of older bridges instead of spending the time and money to construct entirely new ones. The latest example is the Tuttle Creek Bridge on K-16 near Manhattan. KDOT asked the group to look at the 5,350-foot steel bridge and its fatigue cracks. Initial estimates found that the state would have to pay $50 million to replace the bridge, but the research team proposed repairs that were made for $15 million. The bridge has not developed new cracks since, and it is estimated to have 100 more years of life.
Ben Kaan, Wheatridge, Colo., graduate student and member of the group, said many bridges were designed correctly at the time they were built, but now more is known about bridge fatigue, and the bridges need repairs.
“The majority of our infrastructure is getting old, and many bridges were only built to last a certain amount of time,” Kaan said.
Much attention has been thrust upon the state of U.S. bridges since the collapse of the I-35W bridge in Minneapolis that resulted in 13 deaths.
“Whenever there is such a tragedy, people understand the consequences of not paying attention to these issues,” said Adolfo Matamoros, associate professor of engineering. “This is a very significant problem and this is never going away.”
The group also is developing ways to let the bridges signal their own fatigue before it is too late. They are working with aerospace engineers to develop indicators that could be placed within steel bridges.
“Some composites can show fatigue with indicators that pop out and emit a red dye when the bridge is at risk,” said Ron Barrett-Gonzalez, associate professor of aerospace engineering. “There is a flow of technology that has a place in civil engineering.”
— Edited by Amelia Freidline
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