Bridge fires can present a severe hazard to the transportation infrastructure system. In fact, a nationwide survey by the New York State Department of Transportation (NYSDOT) has shown that fires have collapsed approximately three times as many bridges as earthquakes. Bridge fires are often intense as they may be fueled by gasoline from vehicles that have crashed in the vicinity of the bridge. Additionally, code recommendations and guidelines for fire protection of bridges are lax. Large fuel loads and a lack of code requirements for fire protection of bridges have left bridges quite vulnerable to fire, particularly unprotected steel bridges, which was established in recent research. The research focus has mainly been on traditional carbon steels at elevated temperatures and bridges of simple geometry such as plate girders. It is therefore necessary to expand on this research to include additional materials such as weathering steel and additional bridge geometries such as curved box girders.

Weathering steel has been widely used by State DOTs for construction of steel bridges because of the maintenance cost savings. New York State DOT’s preferred structural steel for bridge girders is weathering steel, and it was reported that they owned more than 1200 weathering steel bridges in 2000. 2 Weathering steel forms a protective layer of rust (patina) to prevent corrosion of the steel and only recently have the mechanical properties of weathering steel at elevated temperatures been determined. The determination of these properties allows for discussion of the behavior of weathering steels in fire. Additionally, curved box girders are often used in large highway bridge interchanges. The special geometry and loading conditions of curved box girders adds to the complexity of the bridge fire problem.

The work described in this proposal is part of a larger testing program to investigate the behavior of curved weathering steel box girder bridges subject to fire loading. Phase I (to be completed as part of the proposed work) will begin with an investigation into the behavior of curved traditional (non-weathering) steel box girders subject to fire loading and Phase II (to be completed later) will expand on

Related Publications:

Braxtan, N.L., Whitney, R., Wang, Q., and Koch, G. (2015). “Preliminary investigation of composite steel box girder bridges in fire.” Bridge Structures, 11, 105-114.

Braxtan, N.L., Wang, Q., Whitney, R., and Koch, G. (2015). “Numerical analysis of a composite steel box girder bridge in fire.” Applications of Structural Fire Engineering 2015 Conference Proceedings