FRP WRAP GIVES OLD BRIDGE NEW LIFE
By Kevin Wilcox
May 9, 2017—East Lynn Lake, in scenic Wayne County, West Virginia, is a popular destination
for outdoor enthusiasts, drawn by the reservoir's many species of stocked fish as well as
boating and camping opportunities. The reservoir is part of a flood control project completed in
1970 and is operated by the U.S. Army Corps of Engineers district headquartered in Huntington,
The only route to the lake crosses a 126 ft long
concrete bridge founded on steel bents, and over
the decades, those steel H-pile bents have
corroded significantly. In 2013, roughly 44 years
after the bridge was completed, the Corps
reduced the span's capacity from 15 tons to 6
and limited traffic to a single lane.
Replacing the bridge would have been complex
and expensive. It would also have required
discarding a reinforced-concrete deck that was
still in good condition. Instead, a team of
researchers from West Virginia University
(WVU), working with the Corps in an initiative
sponsored by the National Science Foundation
called the Center for the Integration of
Composites into Infrastructure, successfully
rehabilitated the bridge and in the process
validated a process for renewing the rusted steel
bents with fiber-reinforced polymer (FRP) jackets.
The FRP composite used in the project begins with a flexible sheet of glass fiber that is bonded
with a polymer resin. The resulting material is exceptionally strong and airtight, two qualities
needed for the East Lynn Lake bridge.
The team was led by Hota GangaRao, Ph.D., P.E., F.SEI, F.ASCE, the Maurice A. and Joann
Wadsworth Distinguished Professor of Civil and Environmental Engineering in WVU's Benjamin
M. Statler College of Engineering and Mineral Resources. GangaRao directs the school's
composites center and has been experimenting with FRP for decades, but this was the first time
he had used it to rehabilitate rusted steel structural members.
"The challenge was how [we were] going to use this kind of material without disturbing the
basic configuration of the steel bridge structure," GangaRao recalls. "The steel wide-flange
columns were badly corroded. How do I transfer the forces from the bridge deck to the columns
[and] from the columns on down to the foundation? That was a challenge. Then how do I wrap
this inconvenient cross section?"
So he contacted material suppliers and selected a fiber jacket manufactured by Simpson
Strong-Tie Company, Inc., of Pleasanton, California, that could encase a column as a
continuous unit, as well as a fiber wrap from Air Logistics Corporation, of Monrovia, California,
that could be installed around that jacket.
Early exploratory work found that the steel bents were well preserved just 2 ft below the mud
line. The team used a power washer to remove rust scales from the bents, treated them with a