University of South Carolina

Engineers involved in national study on aging bridges

Researchers at the University of South Carolina’s College of Engineering and Computing are part of a national team that will develop technologies to assess the structural health of the nation’s aging bridges.

The National Institute of Standards and Technology (NIST) awarded the $14 million project through its Technology Innovation Program (TIP) that links the Physical Acoustics Corp. (PAC) of Princeton, N.J., the University of Miami, Virginia Tech and the University of South Carolina, with $4 million for its part of the study.

“The technology being developed involves combining data from a host of electronic sensors – including embeddable low-profile piezo-electric sensors – and new methods that analyze and rapidly assess data on bridge corrosion, cracking due to fatigue and other defects, even before they’re visible to the eye,” said Dr. Paul Ziehl, an associate professor in the department of civil and environmental engineering and the lead investigator for Carolina’s research.

“This study addresses a critical need in the nation’s infrastructure,” he said. “Many of our bridges were built 50 years ago, and many of these structures have a life expectancy of about 50 years. This project focuses on steel and concrete bridges. What we learn will help us to more quickly determine the health of a bridge and the length of time that it can be used.”

The Federal Highway Administration estimates that more than 70,000 bridges in the United States are structurally deficient. According to NIST, about 10,000 bridges are built, replaced or repaired annually.

“This underscores the need for a system that will give us ongoing, reliable information about the structural health of the existing bridges so that repairs can be prioritized and accidents averted,” he said.

At the heart of the research is a network of high-tech sensors, including passive piezo-electric monitoring (acoustic emission), which Ziehl has been developing for assessing civil infrastructure. Dr. Victor Giurgiutiu, a professor in the university’s department of mechanical engineering, will lead the research in active piezo-electric sensing, which brings a new and critical dimension to the project.

Passive acoustic emission sensors can detect cracks in steel bridges and measure damage caused by corrosion, for example, in reinforced bridges. Active sensors have the ability to study the structure at will and image damage remotely. Active emission monitoring has been used to detect the structural safety of jets and on railroad tank cars carrying chemicals but has not been used widely in civil engineering.

“Most bridge failures occur in a localized region from degradation mechanisms, such as fatigue and corrosion,” Ziehl said. “This research will enable us to strategically place sensors on bridges, collect data from the sensor network and analyze that data with the development of new computer software and models.”

Ultimately, the study will give bridge owners a high-tech system to detect problems early.

“Bridge owners will be able to make informed decisions, set priorities and determine where remote monitoring will be cost effective,” Ziehl said.

The S.C. Department of Transportation is collaborating with the University of South Carolina and has contributed several bridge girders for the study.

The research team also includes Dr. Juan Caicedo (numerical modeling and bridge prognostics); Dr. Sarah Gassman (foundations), and Dr. Nathan Huynh (assessment of the transportation network) from the department of civil and environmental engineering; and Dr. Lingyu Yu (active sensing) from the department of mechanical engineering.

Extending lifespans

  • What: $14 million NIST project.
  • Who: Three universities and one research lab; College of Engineering and Computing to work with $4 million of the grant.
  • Why: To identify potentially dangerous flaws in the nation's aging bridges.

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By Office of Media Relations

Posted: 05/28/09 @ 12:00 AM | Updated: 06/24/09 @ 4:11 PM | Permalink