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.
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.