rust inhibitor, and determined the best locations for welding steel studs. These studs would help
transfer loads to the concrete that was to be poured around the bent.
Once the round jacket was slipped around the bents and "zipped up," GangaRao explains, the
team placed a special epoxy concrete into it up to a point above the waterline and then filled the
rest with conventional concrete. Once that was complete, two more layers of FRP were
wrapped around the fiber jacket.
"This provides a huge amount of reserve strength
to each and every one of those columns,"
GangaRao says. "In addition, concrete and the
FRP jacket hermetically sealed the corroded
columns; therefore, there is no oxygen content
going in there. We put some corrosion sensors in
that bridge, and we are not finding any kind of
additional corrosion-related activities progressing.
It is completely arrested."
The team conducted static and dynamic load tests
of the bridge both before and after the
rehabilitation. Those tests revealed that the load-
carrying capacity was 10 times higher under static
loads and 6 times higher under dynamic loads
after the project, GangaRao says. This enabled
the Corps to return the bridge to its original weight
"We expected it to perform that well," GangaRao says, adding that knowing it on paper and
demonstrating it in the field are different experiences. "You always feel good when it performs
the way you expect it to perform based on computational analysis."
The bridge is now outfitted with a series of strain gauges, temperature monitors, and corrosion
sensors. A team under the supervision of Udaya B. Halabe, Ph.D., P.E., F.SEI, F.ASCE, a
professor of civil engineering at WVU, continues to monitor the performance. Mark Skidmore,
P.E., M.ASCE, an engineering scientist at WVU who participated in the rehabilitation, is
responsible for this ongoing effort. The data coming back from the sensors indicate that the
rehabilitation is working as planned.
As an added benefit, the project took just three weeks to complete, compared with perhaps
more than a year for a full replacement.
GangaRao is investigating the longevity of FRP materials in the field, which is an open question
for the relatively new material. He is also exploring how the material might be modularized so
that it could be delivered to jobsites with the resin and polymer already bonded, which would
minimize inconsistencies in on-site application methods.
"FRP renewal is not a panacea, but [when] it can be done—especially coupled with
conventional construction materials—it saves huge sums of money," he says. "Europeans do a
much better job of preserving their infrastructure than we do. Somehow, we have a culture of
get rid of it and replace it with a new one.
"We spent about 20 to 25 percent of the replacement cost for rehabilitating this bridge," he says.
"My message is simple—do not rip and replace, but renew with FRP where possible."