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SDSU researchers part of new national transportation center

A double-tee girder, which was 50-ft long and was salvaged from a 45-year-old bridge, is monotonically tested to failure at the Jerome J. Lohr Structures Laboratory. As part of a new national U.S. Department of Transportation center, South Dakota State University researchers will determine how to retrofit and extend the life of existing bridges and roads and develop new construction techniques.

South Dakota State University researchers will develop innovative techniques to repair and construct bridges and roadways through a new U.S. Department of Transportation-funded research center, according to Mostafa Tazarv, assistant professor of civil and environmental engineering.

SDSU is part of a consortium of 11 universities working to improve the durability and extend the life of transportation infrastructure through the National Center for Transportation Infrastructure Durability and Life-Extension. The center is one of seven national university transportation centers created through the 2015 FAST Act—Fixing America’s Surface Transportation, which provided $350 billion in funding for transportation research.

Mostafa Tazarv
Mostafa Tazarv

The new center, which involves 30 researchers, will receive $7.5 million through the three-year U.S. DOT grant. South Dakota State researchers will get approximately $140,000 per year in federal funding that will be matched with regional and state transportation funding. Tazarv, who leads the SDSU team, estimated the project will provide research funding for three civil engineering faculty members and three graduate students.

“Our focus will be on developing techniques to repair and replace bridges, roads and even pipelines,” said Tazarv. His research examines ways to enhance the performance of bridges and bridge components by using innovative materials that reduce damage due to severe events, such as earthquakes and flooding.

A 2016 American Society of Civil Engineers Infrastructure assessment reported that more than 9% of the nation’s bridges are considered structurally deficient and 1 out of every 5 miles of highway pavement is in poor condition. This year, South Dakota transportation officials are also coping with damage due to spring flooding.

Rouzbeh Ghabchi using pneumatic pullout device
Assistant professor Rouzbeh Ghabchi adjusts the pneumatic pullout device as part of work to determine how moisture impacts the adhesion of the binder to the aggregate.

“These aging structures are more vulnerable to extreme climatic events, such as heavy precipitation, flooding and frosting,” said assistant professor Rouzbeh Ghabchi, who is the project co-investigator. “The research conducted through this center is expected to help improve the serviceability and life cycle of these structures, which are critical to farmers being able to move their machinery to the field and haul their crops to elevators and processing plants.”

Ghabchi, who is in charge of the asphalt and concrete laboratories, has been conducting research to improve the durability of South Dakota roads. He has looked at the effect of moisture and freezing on South Dakota asphalt mixes and developed guidelines for tack coat application.

Tazarv and Ghabchi will collaborate with researchers from Washington State University, which leads the center, and other participating institutes, such as Case Western Reserve University in Cleveland, to address issues related to protecting transportation infrastructure against multiple hazards and improving system response and resilience.

As coordinator of the Jerome J. Lohr Structures Laboratory, Tazarv has done full-scale testing of five bridges. He developed a cost-effective method of rehabilitating the longitudinal joints in double-tee bridge girders and recently conducted strength testing on a concrete girder salvaged from a 45-year-old decommissioned bridge.

“We can bring a specimen into the lab, use a repair technique on it and test it again to see how much extra strength it has and determine whether it can meet current requirements,” Tazarv explained.

In addition to determining how to retrofit and extend the life of existing bridges and roads, Tazarv said, “We will work on developing new construction techniques that will reduce the time it takes to replace a bridge.” For instance, he continued, “If you can replace a bridge and, rather than working two years on the site, construct that bridge in six months, how much will you save?”

Precast components are more expensive but using them reduces labor costs. “In the Dakotas, it is also difficult to find construction workers. If we can reduce the time on-site, we can make better use of our resources,” Tazarv noted. In addition, he will use a lifetime cost analysis that considers, not only construction costs, but also how bridge or road closures impact residents. “It gives a big picture view of cost,” he added.