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| Jeffery Volz |
CEES Assoc. Professor Jeffery S. Volz’s research project on fiber
reinforced polymer bridge decks is currently highlighted by ASCE’s “Journal of
Bridge Engineering”. The abstract and
details can be found at http://ascelibrary.org/journal/jbenf2
A brief synopsis of the research follows.
The deterioration of our nation’s infrastructure is an almost daily news
item that attracts passionate political, economic, and socio-economic
discussions. One of the leading causes of this deterioration is the “bare roads
policy” adopted by the majority of state highway agencies during the 1960’s.
This policy involves the application of deicing salts on state roads during
winter months to reduce traffic accidents, injuries, and fatalities. An
unfortunate side effect of this policy is that deicing salts attack the steel
embedded in reinforced concrete bridges, leading to premature deterioration. In
2001, a study sponsored by the Federal Highway Administration predicted that
the U.S. will spend an estimated 8.3 billion dollars annually over the next ten
years in an effort to repair or replace bridges exhibiting corrosion-related
damage, with indirect costs exceeding 10 times that amount.
Although still in their infancy, fiber reinforced polymer bridges have
shown great promise in eliminating corrosion concerns and meeting or exceeding FHWA’s
goal of 100-year life spans for bridges. While FRP bridges are cost-effective
in terms of life cycle analyses, the combination of higher first costs and
limited state department of transportation budgets has restricted their use.
One area that has shown some headway is the use of FRP for bridge decks, focusing
on the location where the majority of corrosion-related damage normally occurs.
However, first costs still hamper widespread use of this approach.
FRP bridge deck panels offer superior corrosion resistance, at one-fifth
the weight of reinforced concrete. However, current FRP bridge deck panels typically
rely on an intricate geometric honeycomb system between the top and bottom
layers of the sandwich panel. This labor-intensive honeycomb construction
doubles the cost of FRP panels compared to reinforced concrete. Although cost-effective
in terms of longevity of the bridge and overall reductions in weight, the lower
first cost of reinforced concrete precludes the use of FRP bridge decks in the
majority of situations.
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| Fig. 1 |
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| Fig. 2 |
Working with a composite manufacturing company in Florida, several state
departments of transportation, and Bayer MaterialScience, Volz’s research team developed a novel FRP bridge deck configuration
that incorporates a new two-part, thermoset, polyurethane resin. This
combination of simplified configuration and manufacturing with the new resin
system has resulted in a bridge deck panel that is very nearly competitive with
reinforced concrete on an initial cost basis. After several years in
development, the research team recently completed fabrication and testing of a
full scale deck panel, shown in Figure 1. The panel has a depth of 9-1/4”,
width of 2’-6”, length of 9’-8”, and span length of 9’-2”. The panel supported
a peak load of 83.3 kips (83,300 lb) or very nearly 4 times the AASHTO design
truck wheel load of 21.3 kips. A plot of load versus deflection during the test
is shown in Figure 2. The panel performed exceptionally well during the load test
with failure precipitated by buckling of the sloping webs of the panel.
The research team is currently developing and testing construction details
necessary to implement FRP deck panels on an actual bridge, including
panel-to-panel connections, panel-to-girder connections, bridge skew, roadway
crown, bridge rail attachment, and deck drainage.
