Photo courtesy of USC News Wireless sensors, such as the one held here by Dr. Paul Ziehl, are being developed by the College of Engineering and Computing to red flag potentially dangerous flaws in the nation's aging bridges.

The National Institute of Standards and Technology (NIST) awarded a $14 million grant to study the structural health of the country's aging bridges. USC will get $4 million of the total, and the rest is distributed among the Physical Acoustics Corp. of Princeton, N.J., the University of Miami, and Virginia Tech.

"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 USC's research.

"This study addresses a critical need in the nation's infrastructure," said Ziehl. "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 more quickly determine the health of a bridge and the length of the time that it can be used."

Dr. Victor Giurgiutiu, a professor in the universi- ty's department of mechanical engineering, will lead the research in active piezo- electric sensing.

Of interest in Columbia, for example, is the Gervais Street Bridge, completed in 1927, which is upstream from the McMillan Bridge, built in the early 1950s, connecting Blossom Street and Knox Abbott Drive.

A 50- year structural life can be expected with highway bridges designed and built under low- ball budgets, but the Brooklyn Bridge opened for traffic in 1883, and the Ponte Vecchio (Florence, Italy) still stands over the Arno River with its structure intact since 1348.

The research team includes Dr. Juan Calcedo (numerical modeling and bridge prognostics), Dr. Sarah Gassman (foundations), and Dr. Nathan Huyah (assessment of the transportation network) from the department of civil and environmental engineering. Also on the team is Dr. Lingyu Yu (active sensing) from the department of mechanical engineering.