In this research project the use of full-depth precast concrete
deck panels for rapid bridge deck installation 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 plans and specifications
were developed for implementing the system on a bridge on I-90
over Door Creek near Janesville, Dane County, Wisconsin. The plans
and specifications were developed in cooperation with private
consulting firm Alfred Benesch and Company. The plans call for
the new system to be constructed to carry the eastbound lanes
and a nominally identical "twin" structure built using
conventional cast-in-place concrete to be constructed to carry
the westbound lanes. Construction is scheduled to begin in spring
2005.
In
general, the use of full-depth precast concrete deck panels offers
an alternative to conventional cast-in-place concrete decks. These
panels are constructed off-site under controlled conditions and
brought to the site ready for installation. Precast concrete deck
panel construction takes less time and thus creates less interruption
to motorists. In most situations, the bridge can be built using
only night closures, or in certain circumstances staged construction
can be implemented to maintain traffic in both directions. Other
advantages include increasing work zone safety by reducing the
number of and exposure time of workers operating near moving traffic,
and reducing environmental impacts by minimizing the site access
footprint.
Each of the Door Creek Bridges has an 83' single span with 30°
skew. The existing bridges are currently 40'-2" wide, however,
part of the project is to widen the bridges to 64'-6". Each
of the bridges currently has five 60" deep steel plate girders;
three additional girders will be added to each structure in order
to accommodate the widening. The plate girders are spaced at 8'-10"
on center and are built up from A36 steel plates. The deck will
be made to act compositely with the plate girders through the
use of shear studs welded to the top flange plates. The bridges
will be constructed in stages; traffic will be carried on half
of each bridge while construction is occurring on the other half.
This means that in additional to transverse joints between the
panels there will be a longitudinal construction joint running
the length of the bridge. The panels will be post-tensioned in
both the longitudinal and transverse directions in order to hold
them together in place.
A
total of 22 panel specimens (full and half-scale) were constructed
and tested in WSTML in order to verify the system's strength,
serviceability, and constructability. A total of 4 different tests
were performed. The tests were: Edge Loading, Longitudinal Joint,
Transverse Joint, and Composite Behavior. The edge loading test
simulated the effect of a wheel load on the edge of the panel,
which may occur during staged or night construction. The purpose
of the longitudinal and transverse joint tests was to analyze
performance of the longitudinal and transverse joints under bending,
and to determine when bottom joint opening (cracking) occurs at
different post-tensioning levels. The purpose of the composite
behavior test was to analyze the composite action between the
concrete deck panels and the steel plate girders using two different
shear stud configurations.
The
UW will continue to be involved in this project through the construction
phase. Anticipated activities include keeping records of materials,
labor, and equipment required to construct both bridges in order
to compare the prototype system to a conventional system, monitoring
the construction schedule in an effort to predict the minimum
amount of time required to implement the prototype system in a
rapid-construction scenario, and observing the construction activities
in order to identify any problematic details and recommend revisions
for future designs using this innovative system. The UW will also
conduct load tests of the completed structures in order to verify
the structural adequacy of the as-built structures and relate
the performance of the laboratory specimens to the completed bridge.
