In
this research project the use of a new combination of Fiber Reinforced
Polymer (FRP) composite materials to reinforce bridge decks was
investigated. In the course of the research laboratory tests were
conducted in the Wisconsin Structures and Materials Testing Lab
(WSMTL) at the University of Wisconsin-Madison (UW) and a new
bridge was constructed on US Highway 151 near the city of Waupun,
Fond du Lac County, Wisconsin utilizing the innovative FRP reinforcing
system. During construction quality assurance tests were performed
on the FRP materials to ensure compliance with the special provisions,
which had been developed for this project in collaboration with
Alfred Benesch and Company. Constructed adjacent to this innovative
bridge was a nominally identical (except for ½ inch difference
in deck thickness) steel reinforced bridge to serve as a basis
for comparison.
FRP
reinforcement provides a corrosion free alternative to traditional
steel reinforcing. Utilizing FRP reinforcing will lengthen the
service life of the bridge deck by avoiding the destructive cycle
of concrete cracking, followed by corrosion of reinforcing, which
in turn worsens cracking. The FRP reinforcing system also made
use of stay-in-place deck forms, which reduce labor costs, construction
time, and increase construction safety. Once construction was
complete, load testing was carried out in collaboration with the
University of Missouri-Rolla. The purpose of this research was
to demonstrate the use of an innovative non-metallic, cost-effective,
FRP reinforcing system for concrete bridge decks to a new bridge
in the State of Wisconsin.
During
the design phase the UW conducted experiments to determine the
physical and mechanical characteristics of the FRP materials while
concurrently carrying out tests of full-scale prototype composite
FRP reinforced slab and beam specimens in the laboratory. The
concrete slab specimens were all 8" thick and ranged in plan
area from 9'-0" X 8'-0" to 9'-0" X 11'-6".
The 200,000 lb capacity MTS closed-loop, servo-hydraulic actuator
in WSMTL provided loading to the concrete deck panels in a manner
consistent with the typical bridge design vehicle. The beam specimens
were also 8" thick and all were 3'-0" wide. They ranged
in length from 10'-10" to 17'-4". The longer beams were
simultaneously loaded using the same 200,000 lb capacity actuator
that was used for the slab tests as well as the adjacent 55,000
lb capacity actuator in order to simulate multiple bridge spans
being loaded simultaneously. Findings from the laboratory tests
enabled the design and construction of the FRP reinforced bridge
to move forward.
The UW also conducted construction phase monitoring including
evaluating the FRP manufacturers' test results for compliance
with the project specifications, conducting independent quality
assurance tests on FRP materials, and keeping records of materials,
labor, and equipment required to construct both the steel reinforced
bridge deck and the FRP reinforced bridge deck so that a comparison
could be made between the two. The six specific quality assurance
tests carried out in the WSMTL were: Longitudinal Tension test,
Longitudinal Short Beam Shear test, Fiber Volume Fraction test,
Water Absorption test, Dimensional Tolerance test, and Measure
of Aggregate Distribution on the FRP deck forms. Based on the
construction observation it was found that the FRP reinforced
bridge deck cost more than the steel reinforced bridge deck, however
it was not far greater than the cost of other comparable bridges.
Shortened construction time for the FRP reinforced bridge was
also documented.
The
major finding of this research was that the FRP reinforcing system
was a viable option for new bridge construction, especially in
situations where shortened construction time is important. The
bridge was successfully constructed and is currently open to traffic.
