Hillman thinks manufacturers have to think differently. “There’s a tendency when we’re focused on one aspect of an industry to think there’s only one solution, but a lot of the great advances in technology are facilitated by cross-pollination between two industries. I view composites in the same way; they have tremendous properties, but not the perfect properties for everything we need to do. Marrying that with conventional materials can compensate for the deficiencies of FRP and exploit its good characteristics,” he says.
#3: Opportunities Exist Beyond Bridge Decks
Perhaps the most prominent bridge component is the deck – the transportation foundation of the structure. However, composites may not yet be equipped for wide usage in this application. Paul Liles, state bridge engineer for Georgia DOT and chairman of AASHTO’s T6 FRP committee, says heavy truck usages pounds composites. “Heavy truck traffic is very tough on structures. With most building products, you analyze it and it may look fine, but trucks seem to pound it apart. Composite decks suffer from such maladies as splitting along layers of fibers and delaminated overlays. It’s one of those things where you go through the equations and everything looks fine, but there are other factors to consider,” he says.
Still, that doesn’t mean composites don’t have any opportunities in bridges. Pedestrian bridge systems, which are smaller and designed for people to walk across, are incorporating more composites. “The loads for those are less, and lighter systems are needed due to such variables as access to a construction site,” says Witcher.
FRP structural strengthening systems (often called wraps) and repairs are also opportunities. “When a contractor damages a beam, repairing with carbon fiber is the most cost-effective solution for them,” says Liles. Some questions linger about how long the repair will last, though. “The industry tells us different amounts, from 15 to 25 years for exposed conditions, and we don’t know. However, it’s been out for 10 to 15 years and we’ve seen no reports of taking it down,” adds Liles.
#4: University Research Helps the Composites Cause
West Virginia University (WVU) was one of the first schools to research composites in bridge applications and apply that knowledge to real-world applications. Dr. Hota GangaRao, engineering professor at WVU, has helped implement FRP in wraps and decks in approximately 15 bridges in four states since he started researching the area in 1987.
“Education certainly hasn’t hurt,” GangaRao says. He has helped advance industry use of composites through seminars, shop courses and additional field implementation. “Even providing a booklet to undergraduate students in basic terms, not complicated forethought, can help aid their understanding,” he adds.